Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - Fred8

Pages: [1] 2
Changfa Engines / Re: Slow rpm Chang fa?
« on: November 13, 2021, 01:05:50 PM »

Here is some stuff that might be of interest. It shows some of the info your requesting.

Thanks for proving exactly what I have been saying.

Kubota EB series engines:

The documents show an engine speed RANGE of 1400 to 2800 RPM on one of these engines and a similar RANGE on the others.  It also shows what the power output is at those lower than max rated power speeds. I don't see anything that says don't operate below this speed or only operate above this speed. 

For my application 2600 rpm’s works best with my EB300 genset.
And for another lower load application 1800 May have been perfectly fine and does not mean the engine is going to self destruct as you have implied previously.  YOUR application is not necessarily the same as everyone else's.

As the graphs show and as I was saying, the output is different at different RPM.  If your engine needs full or close to max RPM for the load on it so it does not Lug, then obviously it will be happier and that's the place to run it.  If the load on the engine is equivalent to what it will put out at a lower RPM, Then Running it at that speed is not going to destroy it because the power  output at that speed is sufficient.

Honda GX390 Tech Manual:
Pages 3 and 4 shows recommended engine speeds.

SPEEDS being the operative word.
Here we see an operating RANGE of 2000 to 3600 RPM.  That is neither " extremely slow"  nor is operating the thing at any speed above 2000 going to cause problems providing the output of the engine at that sped is sufficient for the load.

I also see a note: " Operate the engine at not more than 90% of the maximum horsepower available at a given rpm".  Again what I have been saying, the output changes with engine speed.  And again, it would seem obvious not to lug an engine which will occur then there is too much load for the power produced at a Given RPM. I would have thought people playing in this game would also realise there is no point to running an engine at a speed where it is say producing 10 Hp when the load is only going to generate a max of 5 HP.
Slowing the engine down in this case will save fuel, noise and wear and tear. But it does not seem to agree with the forum agreed position.

Page 10 Resonance Check (critical speed)

This is more to do with the equipment attached than the engine itself. It talks about with the equipment and the engine loaded.

On this modern engine and the Kubot,a There is no referral to Minimum engine speed or speeds to avoid.
I did not look at the first example, there was a warning on my browser about the file so I did not download it. Being a Military engine It would be more than conceivable it had certain and critical parameters.  Same with the old engine mentioned. Obviously if the engines have this specified one would be smart to observe it but how many MODERN engines that one can get now have this?
On the modern engines given as examples, there is proof they CAN be operated at lower than max recommended RPM and I see no suggestion let alone proof that running them outside of the max rated power speed will damage them.

Obviously if there is some specialised engine or something old that has a Min RPM for whatever reason that is different but I would say that does NOT apply to the majority most people are going to use here.

I was surprised that a Honda could have such bad vibration at the speeds mentioned.

Engine isn't going to be perfectly balanced at every speed and I note the range you mention is far from the  " extremely slow" You have repeatedly mentioned but also repeatedly failed and obviously avoided to specify what that is and who has said that most likely because you are the only one saying it. 

Clearly there is a forum position that is the accepted one on this and none other will be considered.
If people want to run their engines at full rated speed even if not needed, all good by me.  Shame there is not more emphasis on fact than going with the group mentality even when proven by the manufacturers documents shown it's not the hard and fast rule it's made out to be.

Carry on!   ::)

Changfa Engines / Re: Slow rpm Chang fa?
« on: November 10, 2021, 02:11:50 AM »

1. those that operate within the manufactures recommendations, probably best for longevity.

This brings up an interesting point......

I have NEVER seen a manufacturer recommend ANY engine speed.
What I do see is a power output figure at a specific RPM. Sorry to anyone that thinks otherwise but that is NOT a recommendation to operate at that speed, it's a RATED power figure at what that engine will do, normally a MAXIMUM  output figure, still below max RPM, NOT what you should run the engine at.

This is why industrial engines often come with power curve charts to show what they will do at specific  speeds. I am amazed people are not aware of those.
If the Max HP/ RPM figure was a recommendation, why isn't everyone, especially those so concerned with critical speed problems not driving their vehicles round at the Figure given for it's maximum power output which is what these Numbers are, NOT an engine operation speed recommendation. 

The numbers merely tell you what the engine will do at that speed.  That is all.

Perhaps I have missed something and if so I'd sure like to be educated if someone could show me where any manufacturer says something akin to "This is the recommended speed to operate this engine".
That is nothing like a MAX power figure at a certain RPM manufactures specify.

Further more, there is also a max Torque figure specified which is regarded as the sweet spot and where vehicle manufacturers, especially Trucks and things like locomotives try to gear their equipment to.  Cruising speed in a vehicle in top gear is always closer to the much slower max torque figure than it is the max power figure which is far higher up. And again, if Operating the engine slower was going to grenade it, how do city cars especially manage to put around for a couple of decades without snapping cranks or falling apart.

Here is a power output Chart of a Cummins engine.

Engine Model    Max. Power HP (kW)     Peak Torque lb-ft (Nm) @ RPM     Governed Speed (RPM)
X12 500            500 (373)                 1700 (2305) @ 1000                         2000
X12 455           455 (339)                        1700 (2305) @ 1000                        2000

We see here that the peak torque is at half the RPM of the peak power.
Would someone like to ring Cummins  ( or Cat, Kubota, JBC, Yanmar, Detroit, Volvo, Mercedes, Ford, Deutz, MTW, Perkins, Isuzu, Honda, GM or any other manufacturer) and ask if operating their engine at 1000 RPM ( or whatever is)  in the peak torque range, going to cause issues with critical speed failure or damage the engine operating at that speed?

I think we all know what the answer is going to be and that for mine shoots down any of this idea that an engine operated below max power rating will destroy it.  It's simply  maligned fantasy to suggest that as is the idea people would operate an engine at " extremely low speed".

I also looked at the Changfa site being a recognised small engine Builder and while they don't specify Torque Figures I could find,  They do only give RATED HP/ speed figures. No where could I find anything that even alluded to as much as " Engine recommended operating speed. " If anyone can, please link to it because i'd like to see where I missed it.

As such I can dismiss the position of " Manufacturers recommendation" for engine speed as a fallacy and contortion of the truth.
It's not even a Recommended RPM speed, that where specified, is usually listed separately and is higher again.

Calling a manufacturers power output rating as the recommended operating speed is simply wrong and ignorant of what is actually being specified by those whom don't understand what they are reading.   

you should be aware of the engine's critical speed, that is a valid point.  no engine should be operated at critical speed that is if you want it to last and not have some form of premature failure, some of which can be quite catastrophic like broken crankshafts or engine cases, or mounts.

I agree.
I wonder how many people know that or manufacturers that could even be found from?
Again, it is a Single speed or very narrow range, it's not any speed under the max power rating of an engine.

all you have to do is ride a ferry boat or be anywhere around a diesel locomotive
you can feel the boat vibrate like hell as the throttle opens and the rpm passes through critical speed... and you will note the man with the throttle in his hand does not allow the engine to operate at that speed any longer than is necessary. 

A great example.  I would say though that a lot of this is in the drive train however that is just as important to avoid.


small engine's may not demonstrate this effect so plainly, but the thing also has a critical speed that should be avoided.

I'd suggest with a little observation it is discernable and it is at very low speed where anyone with any mechanical sympathy or common sense would not operate an engine and on a small engine would be at a point where the power output would be near useless anyway.
It's also dependent on load.

Just for clarity, please note I am not trying to attack you Bob or what you said personally, your comment just sparked a thought  of a good point that seems to have been missed/ maligned till now and which I wanted to address and clarify.

Changfa Engines / Re: Slow rpm Chang fa?
« on: November 10, 2021, 01:24:00 AM »

Fred8, I modified my post some. Hopefully I cleared some things up.

Well no, you haven't cleared anything up. The points I addressed are unchanged

Some here are hell bent on insisting that an engine has to run at extremely slow speeds for it to last.   

Please Clarify who these " some are"  with links to where they "insist" The engines be Run at extremely slow Speed and exactly what that is.  Best to  clear up any ambiguity and be accurate don't you think?  The only "Insistence" I can see here is your own in that engines have to be run full tilt.  That notion is completely undermined in industry as I mentioned.

[/quote]A matter of fact at Extreme slow speeds, engines can be torn to pieces in a very short time. Unless lots of modifications are done to an engine.

Again, can you specify and give an example of what an extremely slow speed is ( and a link to those insisting on them and what they are specifying as an example would be best)  and can you explain what those Modifications are?

I haven't read every thread here but I'd be real interested to see what those insisting on extremely slow speeds are saying over all and in context.

As for Critical speed,

"The critical speed of a shaft occurs when the shaft rotational speed is at or close to resonant conditions. In this condition the torsional vibration of the shaft increases greatly, and will impose very high shear stress on the crankshaft. These levels of stress could even cause crankshaft failure."

It is A speed, not every speed below maximum speed on an engine.  Most engines have a speed at which they vibrate at a greater degree, harmonics dictate that an engine cannot be balanced at  Every speed.
Furthermore, the load an engine is driving either direct or by belt will also have it's own harmonics and imbalances and transmit those to the engine and change the speed at which it's natural frequency occurs.

"Extremely slow speed" which again without specification can only be taken to mean at or slightly above idle is more likely to be a product of lugging the engine than anything to do with Critical speed.

If running an engine at lower than full speed was such an inherent danger, one would have to wonder why the Transmissions in modern Vehicles are not set up to run the engine high in the rev range as to lower down and use the torque the engine supplies. 
Many vehicles have gone to larger engines  that produce more torque and rev lower for Fuel economy for one thing.

If this Critical speed you speak of is such an issue. There is no way the engine in my vehicle would have a redline of 7000 RPM but cruise at highway speed at less than 1600 RPM and do it literally all day long nor would it be able to idle for hours in traffic Driving the AC and alternator.

I think it would be pretty clear to most interested in facts rather than pushing an agenda to be seen to be right that running an engine at lower than max speed is not going to tear it up and  running the thing near idle which would be extremely slow is stupid and nonsensical in the first place.  Running any engine at half speed is far from extremely slow not is it going to cause the thing to detonate as you infer.

Again, to clear up any misunderstanding, please specify what you believe is " extremely Slow Speed" and give links to examples where people are insisting this.

I always always relish the opportunity to lean something new as I am sure do others.    :)

Changfa Engines / Re: Slow rpm Chang fa?
« on: November 10, 2021, 12:09:19 AM »
Lots here are hell bent on insisting that an engine has to run at extremely slow speeds for it to last. And that is far from the truth. A matter of fact. Extreme slow speeds engines can be torn to pieces in a very short time.

Whom is insisting an engine be run at EXTREMELY slow speeds? Can you provide a Link?  I have NEVER seen anyone mention let alone insist that anywhere so I'd be interested to see where you got that " a lot here" are doing that?

Running an engine at less that full speed  is NOT the same as extremely slow Speeds. Running any engine at around half speed is not either. To me extremely slow would be like Idle and I have NEVER seen anyone recommend that on any forum. The idea that an engine HAS to be loaded up and run at or near full  RPM is extremely ignorant and flies in the face of real world practical applications especially with heavier machinery where longevity due to the cost of having to virtually deconstruct the machine the engine is in to replace it is much more than the engine is worth itself.

Slowing and derating engine speed and output is extremely common in the marine, Mining, power generation agricultural and other application sectors  where oversize engines are slowed and reduced in power output for a number of reasons, Longevity, being a main one.

For the applications and engine sizes of relevance here, running an engine  extremely slow would be producing an output of 1-2 hp and I haven't seen anyone with use of that sort of low power here nor is it discussed anywhere I have seen in the home power generation groups which seems the main interest here as well.

I would think common or not so sense would tell a person that Lugging an engine would be bad for it and unless you were running something like a 3208 CAT at idle, anything in the scope of this Forum would produce useless power at very low speeds and be non viable anyway. That is a whole lot different to running something at reduced speed though.
You would most likley be well enlightened to look up how engine manufacturers rate their engines at Various RPM and see what the Military, power generation and pumping industries do as far as sizing and the speed they run different engines.

Never heard of anyone running an engine extremely slow but that's a big difference between running it under Max RPM and de rating it accordingly. 

Exaggeration of what people are saying to suit ones own proclivities however is a different matter.

Changfa Engines / Re: Slow rpm Chang fa?
« on: November 07, 2021, 12:34:32 PM »

despite the Misinformation and ignorance  people spread about running Diesels slow, you CAN run any engine at low speed if you do it right and without problem.  It's a standard practice in industry to over size and under drive/ rev engines.  Many industrial engines have charts to show what power they make at what RPM.
It's simply a matter of matching the engine speed to the power.

If an engine makes 100HP at 2500 RPM, it will make ( say) 20HP @ 1200 RPM.  if you are putting an 18 HP load on it and turning it at that speed, The engine IS in fact working and will work fine.  I have read a lot where people say engines need the ring revved out of them constantly or they will fail which is just poppycock.

For a generator, gear the head to give the desired RPM  at the RPM the engine delivers the required power and thats it.  Will still be working hard but will not be as stressed or wearing out that fast.

You could easily run an engine out a vehicle this way and get slow speed and long life with good economy. I'm negotiating now on a 90Hp 4 Cyl engine that I want to put on a 10KW head.  Will run nice and slow and quite in that setup with an electronic governor  and last a VERY long time.

Everything else / Re: Lithium cell balancing
« on: November 07, 2021, 12:24:26 PM »

Now that I have 2375 watts of PV, I haven't had to do any LIster/Generator battery charging even on cloudy days.

A very modest amount of panels.  Beyond my imagination how you can manage that.  Then again, I spose your generation factor is a lot higher than mine but still....

Here you can buy good used 250W panels for  $50 very easily, often less if you are prepared to bargain. They come and go in supply but sometimes there are plenty around and sales are slow so if you haggle, You can get them cheaper.  I bought a batch of brand new panels earlier in the year for $16 ea for 290s.
They were leftovers a distributor had buried in the back of his warehouse and only was prepared to sell in one lot. I knew he'd have lots of enquiries for ones and 2 and other piddling amounts  so I made him an offer for the lot which he took.  Forked the set of 28 onto my truck still in the Boxes and he was happy to sell them.

 Took some of the 250's I had on my roof down and replaced them with these and sold the 250's at $40 ea.  ;D
The guy I was selling them to wanted to upgrade his 190W panels and go up to 6Kw.

Batteries here are never cheap. Most people selling them used want delusional money and they are usually pretty suspect as to condition anyway. There were loads of 190 Ah UPS backup batteries being offered here by some different sellers Recently.  All 10 Yo and they all wanted over $1.50 to $2 /Ah for them.  Too much of a risk for me.

I regard 5Kw as a basic solar array these days so your power management must be excellent if you can live Frugally enough to survive on half  of that.  5Kw sure would give you a nice buffer and enable you to do a lot more and concern yourself less. You could run your AC and electric stove much more often with less dependence on sunny days as well as not having to worry about using other appliances. 

I think a couple of days battery reserve is good. Would give me more peace of mind.  Having enough panels to  meet your needs even on bad days would be possible for people like yourself whom use little power but for me it would be impractical although quite the dream. I spose it would be a lot more practical if I had wood heating.
 That's by far my biggest power concern and of course comes when there is the least power to be had.  Summer of Course there is plenty of power so I can run the AC much as I like and don't have to worry.

I find if I run it hard and run it early in the day so the house never gets heat soaked I don't need it at night when the sun has gone.

Everything else / Re: Lithium cell balancing
« on: November 06, 2021, 12:43:14 AM »

couple that with a small bank of golf cart batteries (again relatively cheap due to economies of scale), to provide power for the furnace blower, the fridge and maybe a few led lights used after the cogen shuts down in the evening to provide lighting and i think one could make a system that does about everything one would need to do given the constraints of location and size at a low cost and give a good life span.

In that Atypical situation that would work.
How much and what size are the golf cart batteries where you are?  Definitely not cheap or all that readily available here. :0(

add as much solar as one can afford, and the system gets much easier, even if the area is limited in that resource.

This is my philosophy.
I have all my inverters at least double overpaneled.  This has worked out VERY well.  At full output they would overload the HD wiring I put in but it's not about Max power, it's about getting decent power in bad conditions.  Winter fall off where I am is about 1/3rd the summer radiation so that is a big downrating for a start. Add in some Cloudy/ wet weather and I can be down to 10% of my generation I get on a clear summers day. THAT is what I am building for not the walk in 100Kwh a day I can get in summer.

The Kicker is being no natural or town gas, everything is electric so my demands can be huge compared to other people but not out of character for other homes in the area
By having plenty of solar you can run off what is being generated at the time ( on a decent day) without having to dip into your battery reserve.  If you can almost eliminate the day draw on the batteries by running " Direct" then the battery pack can be much smaller.
Thankfully I do not have to contend with Snow or daytime sub zero temps bugger that for a Joke!

Winter days can be mostly clear and beautiful and even the instant generation not too bad below what the summer is thanks to the over panelling  however, the real shortfall comes from having half the daytime hours.  It's the short days that hurt me the most not even the winter radiation fall off.  If I had the inverters running their rated capacity in panels, they would be useless pretty much.
IMHO, anything under 150% Panel to inverter ratio is a waste.  200% I consider to be the sweet spot.

For the most part you can get full rating out of the inverter which adds to more consistency of generation. If I had the inverters matching the panels I'd be getting stupid amperage on the good days and no more on the bad ones when I really need the power.

For batteries I have also found 3 and 4 aspect arrays to be best.  For me that's east, north, west and Flat.  For a battery you want a n even charging input not a peaked one. Getting the early charge after draining at night is also desirable.  Having  a flat panel(s) is beneficial for the overcast days although in that situation one is trying to gain fractions of a very diminished output to start with.

I usually set up a winter ground mount for a bit of extra boost which I tilt to the best winter angle. That was 3.5 Kw this year and a good help. Having perfect winter angle and alignment does give an edge on the roof mounted arrays which are simply NOT worth tilting not that I can do much about orientation. Then again, with one exception, they are all perfectly orientated at some part of the day. 

throw in a spouse and a pack of teenage kids, and all bets are off.  :)

Again why I went Big.
Don't want to have to worry about the women's long showers, washing and drying one article of clothing in the early evening or late at night for the next day, leaving TV's on ( other than wearing out the TV for nothing) and all the other things that I got lectured about when I was a Kid for wasting power.   I have changed all the lights in the place to LED which use nothing but I still can't bear to see a light on in a room no one is in. Old habits die hard.

Everything else / Re: Lithium cell balancing
« on: November 03, 2021, 03:37:15 AM »

"if" one were to rethink his energy needs, i think an argument can be made for the simplicity and low cost of a system based on the lowly golf cart battery.[/quote]

Where I am they are much more exy per KWH than fork packs.  I realise they are much cheaper elsewhere but one has to go with the best bang for the buck available to them.

If they were cheaper, it's only a matter of series/ paralleling them to get the required capacity.  as long as the DOD is not going to be too excessive, I see no problem with them.

now if one wants all the modern creature comforts of modern living, then large traction batteries are likely something that is hard to beat, given a "complete" cost analysis (including risk factors).

This is what I have Found.  At my stage of life I want to enjoy the creature comforts. Not interested in living in a shoe box to save on bills, not interested in going round and unplugging wall packs to save 20W a day, I want to be comfortable and enjoy myself.  I have put up a very large for a domestic solar system and can generate more than I use so I use it within reason. Not stupidly, just so I don't have to concern myself with Running the AC or heating the whole house rather than walking from a warm room to a frigid one.

Fork pack allows these comfort with it's capacity and that of the solar I have and the backup gennys if I need them.

"if" one gets really down in the weeds, and is willing to focus on an efficient system, with low cost per kw/hr, i can make a good argument for the automotive starting battery.

If the Number of batteries was sufficient so they operated within their design parameters of maybe an average discharge of only 10% DOD,  then again don't see why they wouldn't do.  Might only have a 3-4 yr life anyway but if the cost works out, nothing wrong with that.
A Large car battery is around 100 AH which you might have to rate as 10  useable so you would probably want a few but that's a storage not a technical issue.  Cost of leads and terminals between them all might be a significant cost though.

we are probably still 10 years away from getting a quality lithium based battery, that is well protected and has a low risk of failure.

I believe quality Lipos are available now.  It's just the cost of them is excessive and people naturally gravitate to the cheapo 2nd grade cells  which are the good ones that failed in the manufacturing process to meet the required standard of the first quality cells.
If you want good lithiums, they are out there. If you want a good Car Rolls Royce is still available and similarly priced.
I'm happy with a Ford or Gm but some people now are buying those Chinese cars.  Good luck to them!

in the end, it is hard to get a battery with the energy density of a gallon of fuel, as dependable, and at so low a price.

It is in fact IMPOSSIBLE by a very long measure to get a battery anywhere near the energy density of any liquid fuel.  I forget the number but 9x less energy on the best batteries to liquid fuel seems to stick in my mind.
Put it this way, a large car battery has roughly 1 Kwh of energy and that's Pulling it way down below where it's meant to go.  1 Litre of liquid fuel has 10 KWH of energy. Lithiums are better but still impractically short when compared to liquid fuels.

I saw a Doco on this a while back.  They compared some ultra High density battery to liquid fuels and got it to about a quarter I think it was of comparable density.  The battery had to be super cooled and was highly unstable.  They compared the energy density of other materials and said  a battery with the same energy density as liquid fuels is called a Bomb because of the energy that would have to be stored in it and the instability of such a chemical composition.

They also showed what it would take to make a long range airliner electric powered.  Not going to happen in my lifetime or anyone else's here I suspect. One thing they pointed out was the further a regular place goes the lighter it gets as fuel is burned off. With an electric, it's draging round the dead weight of the discharged battery cells the whole distance.  Makes a big difference to the energy required  for a long distance flight.

I have some battery chainsaws and they are great.  No lighter than a similar sized petrol  one but they have great torque and good endurance.  Matter of horses for courses.

Same with EV's. so much less range than an IC.  Say that and the tesla fans jump up saying the model whatever can go so far on a charge.
Not really.

I learned recently when talking to an owner the range is nothing like stated. Go over 80 KMH and the range plummets.  Highway speeds here is 100/110.  At that speed you loose 100km+ in range on these EV's,  Yes, if you want they can " Hyper Mile" along at 80 which is borderline if not flat out illegal on highways here causing an obstruction and adding hours to a journey one can do in an IC in one go, then yes it will go that far. Of course then a 4 hour trip turns into an over nighter by the time one allows for recharging.

I saw a new model release ( when it's available in 3 years or whatever)  where they said it would go this much further thanks to the battery break through. The only breakthrough was making the cell size larger and stuffing more of them in the vehicle. Wasn't a higher energy density, just different packaging.

it appears to me that the lead acid battery still is a strong contender for stationary use.

It has few drawbacks in this application and a huge advantage in cost.

I spoke to someone about Buying some  UPS backup bank batteries that were being replaced earlier in the week.  A sizeable storage room full that are turned every 5 years.  They are being replaced with more LA because they are the most cost effective and reliable in the industry's view.

LA is a Long way from dead yet.
Not well suited to any portable use, the weight savings and power density of lipo  kill LA but for fixed uses, best bang for the buck by a long shot.

Everything else / Re: Lithium cell balancing
« on: November 03, 2021, 02:46:20 AM »

Long story short, he'd had one cell die of sudden short every year for 3 years, and was so pissed at the unreliability of his  very expensive premium matched cells that he was considering changing his power system to locally available 48V fork lift batteries.  ​

I believe I know the gentleman you speak of.  I talk with him regularly.  IMHO the man is  an electronics genius and by nature a very through, rational, well educated and experienced in a wide range of industries and intelligent person as well as very helpful to others.  Far as I'm concerned, if he can't make these things work then they are garbage and unfit for purpose.  There is no way that he did anything but nurse the things with kid gloves and I know he was very disappointed  with them.  He is going to LA fork batteries and I doubt unless given to him he'd every consider  Lithium anything again.

Did he maybe just have bad luck? Maybe but aside from all the other failures people have had, he's had a failed system and been left very out of pocket through no fault of his own. Why would a sensible person do the same thing again and expect a different outcome?
Too big a risk for me because I know I'm never lucky.

already some folks are very pleased with the reliability and lifespan of the very, very expensive BattleBorn 12V LFP batteries in marine applications (where size is a concern and cost is not so important.) 

I have also read glowing reports of the battlebornes and some not so good ones.  I think your statement of Cost not so Important is key here. The things are worth their weight in gold, or at least silver.  As you say, in marine applications, justifiable perhaps but for stationary storage, I do not see the point.  The cost of even 10 KWh of these things would probably by 30 or 50Kwh of LA.

I'm not even sure of the Benefits of Lipo in boats? Weight and size generally isn't an issue  In larger craft over 30 Ft and smaller don't carry many batteries anyway. Generally LA batteries are changed out annually because of the vibration boats experience. I really can't see the Lipos being more reliable and generally larger craft  have House and starting batteries that can be all paralleled for starting and  have reserve on the start batteries anyway.

Even if they took the replacement out to 2 or 3 years, I can't see the Lithiums being cheaper nor work out what the advantage is.
When these vessels carry couple of ton of Fuel, another ton or more of water and weigh 16T plus all up, can't even see what saving 2-300Kg of batteries is going to achieve. If they only have 1-2 Batteries, again, the weight saving would be lucky to be a 1% weight saving over all.

I know Lithiums are all the rage in the Caravanning/ RV game but weight savings there make sense.

Lastly, I'll add that 3 or 5 W, 3.2V zeners do not provide a useful non-manual  balancing system- for many reasons, such as connecting and disconnecting them manually  is a farce,

Sounded like it to me as well simply because of the ability to forget the things while doing the balance and cook them this way. The rest sounded Hokum as well but I'm no electronics expert although it sounded suspect to me so I avoided going down that rabbit hole given the rest of the claims made I knew were complete and utter rubbish.

  Likewise the absurd notion that only US made submarine lead acid batteries are good when I'm surrounded by off grid homes all reliably and affordably run on a variety of LA batteries.

I have no idea what a submarine battery is? I suspect it's nothing but a traction battery of a certain specification/ capacity.  I would bet they are used in other applications like telecoms backup etc rather than being made exclusively for subs. In any case, no matter how good they are, where do I and Joe public get them? Not a lot of Submarine  Supply stores round me as I think My Country only has half a dozen anyway so not going to be able to Nip down to  " Sub supplies are Us"  to grab a few.

That is a well acknowledged fact, and it's why cell voltage monitoring is built into LFP packs; typically charging is disconnected when any cell goes to max voltage, and discharging is disconnected when any cell goes low.  This to required save the cell(s) from destruction. 

No smart or Conscientious DIY pack builder I have read of does without a BMS. Pretty much like running an alternator in your car without a voltage regulator somewhere in the system.
Contrary to the claims made, lithiums are a LOT more sensitive to voltage and charging than LA and to run a Lipo pack without a BMS is merely a ticking time Bomb.

The LFP prismatic cells were then destroyed by excessive voltage.  The cell balancing hardware was also destroyed by too high voltage.  So a complete and total loss of well over $10K worth of new LFP batteries, all a cascade of destruction from a MPPT failure.

I have read of similar occurrences. poor quality BMS that crap out in short order and take everything else with it. Even the preferred brands are not fool proof.  Another common one is not having the setting incorrect for the particular Chemistry.  Some DO LA, lipo, Lif4 etc and all have different parameters. Incorrect setting May not kill them straight away but 6 Months can be enough to render valuable packs useless.

I'm hoping that the quality demands of automotive manufacturers will force rapid improvement in LFP quality and reliability, and the price of bargain B grade cells today will purchase reliable cells in the future.

This will happen eventually but I can't see it for a long time. The relevant thing for me is your next comment.....

I accept that I may still live out my life on lead acid batteries, and at what is now $17/month battery bank replacement cost, I won't lose sleep over that.  I won't switch until it becomes clear that it's cheaper for me to do so.

I -MIGHT- have 20 years left in me.  I'd like to think so but I also think I'm kidding myself a bit.  That means that an LA pack is well within capability of seeing me out.... if they don't come round trying to drag me out my house against my will to administer " Medications" to save my life before hand.  I don't see my electrical needs being much different in time to come and with days of reserve capacity anyhow and a well oversized solar system as well as WVO fuelled generators, what works for me now is still going to be workable in 10 to 20 (Ha!) years.

The only real requirement to me for longevity is  Return on investment.  As long as I get a decen't run out of something so it's amortised cost is reasonable, then what is the problem?  You mentioned $17 month for your batteries.   50 Cents a day is cheap power in anyone's language.  I have friends in the country that pay $1.56  SUPPLY charge then they pay for the power they use on top of that.

I don't need something to last 20 years or even 10. As long as the cost per day/ month works out as being reasonable, I'm not concerned if I have to spend a day every 3 years replacing something and getting new.
If one looks at something like those Tesla power walls, I have never seen a scenario in any country where the cost price can be recoupled in 10 years.  See a lot of convoluted slight of hand accounting to say they can which is largely BS. The maths is real Simple.

They hold 13 KWH of energy useable.  Multiply 13 by the cost of power per KWH in your area. Work out the value of that power over 10 years. This will assume you use that full 13 Kwh every day which will never happen but for arguments sake... Does the value of the power saved outweigh the cost of the battery?  NO! Not even close.  Won't work out over 15 years and then you have lost about 20% I think it is in battery degradation according to official ( and VERY optimistic IMO) figures which blows the ROI out further.

Compare that with an LA pack one may well get their ROI in 4 years and the numbers are very different and even if the things lasted 5 Years you are still ahead over lipo. 
For me, the cost of the power I use from the grid would be almost $5K year.  2 years and I have my entire LA system paid off. 

To me, THAT is a return on investment. 
Anything that take 10+ years  is a Justification for a toy or a hobby, not a financially sound or worthwhile decision.

LA is a financially sound decision for storage. Lithium is merely grandstanding or trying to show off at this point in time.

Everything else / Re: Lithium cell balancing
« on: November 02, 2021, 01:29:59 PM »
Lead acid technology is extremely sensitive to abuse and depth of discharge. There are some that will last twenty years if correctly managed, but one screw up and that is lost.

There is a lot of BS written to promote Lipo ( all lithiums)  and disparage LA and this is some of it.
Lipo is FAR more unforgiving than Lead and sorry, anyone that said otherwise has no experience with the 2 technology's or is flat out lying/ Biased.

Run a Lipo dead flat and try and recover it. Extremely unlikely and if you can it will have bugger all capacity.  Run an LA dead flat and you'll recover it easily and the capacity fall off will be very small IF you only do it once.  Then again, once is all you would get to do it with lipo, no question of that.

Same token, over charge a Lipo and see what happens with that when it swells up and maybe lets the magic smoke escape.  I have BOILED  LA and for some hours and put a load on it to take the overcharge off and they batteries were fine. Not saying there were completely unscathed but they ran as normal  afterwards and only required a bit of a top up.  Not like you can determine a time how long any battery will last to say how much it's life was shortened but with Lipo, one way or the other too far and its game over, dead and buried.

Be prepared to spend 10k to 20k dollars to get a decent sized bank with the 25% max depth of discharge limit for this lifespan.

I cannot comment on pricing where you are but that's ridiculously over the top for where I am unless you are talking about some pie in the sky technology or an unnecessarily large pack.

The bit about 25% Discharge is  regularly recited complete and utter BUNK!

 LA traction ( forklift) batteries are WARRANTED to  not below 80% DOD.  That is , for complete clarity, if you have a 100Ah battery you can take 80 Ah OUT of it  EVERY DAY and that's what the manufacturers warrant it for. 
This is easy to verify, just go to any traction battery manufacturers website and look it up. This 25 and 50% DOD for LA is ignorant Rubbish.
This isn't car batterys we are talking about or some other unfit for purpose type. Then again, even decent car starting batterys wouldn't' be terribly phased  by 30%  discharge especially if they were deep cycle which will handle 50% or better DOD. 

I really don't know why people continue to spread this complete and utter BS about LA batteries nor make out the Lithiums are capable of things they are not. it's misinformation that only causes people to make wrong assumptions and prevents them getting what best suits their needs and is completely unhelpful.  They are batteries for hecks sake, not your children you are trying to get into College. They both have their strengths and weaknesses like anything but why try to make them out something they are not? I don't ever get it but see it all the time.

Where I am, warranted 48V, 720 Ah Fork packs can be had for around $4000, often less.  They are gauranteed for 5 years for solar use provided they are not discharged below 80% . The manufacturers I have spoken to love selling them for solar use.  The current pulled out of them is typically much less, they are not subject to banging and vibration, not discharged nearly as much or run till the shift is over no matter how low they are, usualy set up with auto watering systems, don't have the max charge belted into them in order for them to be ready in the morning or for the next shift and overall have a Much easier life.

One Guy I spoke to said he'd never had a claim with any he sold for off grid use, wished he could say that for their intended application!
Lipo may have some advantages over LA like weight and size which is irrelevant in a stationary application anyway but in Bang for the buck stakes, LA craps on  Lipo.  From what I have read, also does in reliability and longevity.  Read of plenty of people whom have babied the things and they have fallen over in under 4 years.

I have also read miles of BS about lipo taking much higher charge rates than LA.  Again, largely BS. You can't just pump limitless power into lipo at all, not without shortening it's life of course.  OTOH, while LA is Limited in charge rate, the amount of power that works out to on a 6 or 700AH pack is more than anyone is likely to have on their roof in panels unless they are running a solar farm.
Even running .2C is going to be 140A on a 700ah pack and they can take a lot more than that on bulk charge.  How much solar or how big is your generator again?  Also read repeatedly that lipo can be charged at a flat full rate till it comes up to Voltage. Yeah, but it's going to cut the life significantly. In reality they should be given a bult and then a top off charge at a reduced rate similar to LA.  IF you want best life that is.

The LiFePO4 batteries however are not nearly as sensitive to depth of discharge as long as they are never discharged below 2.5v per cell,

And if they are run below 2.5, they WILL Be damaged and maybe unrecoverable depending how low they get.
Not a good idea to Run LA right down either but they WILL recover from it. read PLENTY of reports of people that have locked up their Lithiums through over discharge and can't get even months old packs back up.  Only takes a BMS failure and they are bricked.

These batteries are less than 1/4 price of the same size equivalent of lead acid (at the 25% DOD limit!).

Again, maybe where you live when you work on BS figures like 25% DOD for the LA but I have YET to see any decent lipos cheaper on an AH basis than LA unless you are talking those Chinese Cheapies that are all the rage and have dozens and dozens of Documented failures on Forums. I have seen a lot of people that make this cheaper than LA Claim but they are inevitably quoting 2nd and 3rd rate batteries in chyna and not including delivery and all shipping costs.   And of course if a cell is bad or goes tits up, you are waiting months for a replacement IF the seller Honours any warranty  if there was one and you are undoubtedly up for more shipping and customs costs.
With a fork pack, go to your nearest company and get a standardised replacement off the shelf. Drop the failed cell off at the local Scrappy and you'll get 25-33% of the price of the new cell back.

In my opinion, the price of these will continue to drop and they will become almost "disposable".

Another forum fan boi myth.
There is a HUGE demand for  batteries world wide especially the lithiums. They are bing put in everything these days.  Tesla for one can't get enough and the production of these EV's  is ramping up despite the ignorance of people thinking they are cleaner than FF vehicles increasing demand.
The production of raw materials for Litho type batteries is very limited and mainly carried out in  3rd world politically unstable hell hole countries that have little to no environmental rules and enforcement which makes it infinitely cheaper to process there than bring the materials into first world countries where enviro regulations make the cost far higher.  One little conflict in these countries and production ceases and prices skyrocket.

I have NEVER seen anything in short supply through high demand get CHEAPER  in price.  Does not happen.

If one takes case in point, tesla power walls keep going up in price, around $1000 last year and the year before.  Not aware of ANY battery coming down in price for that matter.
Lipo is as cheap as it's going to get right now.  Add in supply chain problems from Convid and offshoot factors and there is no way  these batteries are going to get cheaper in present chemistry and if something new comes along that will have the elevated introductory costs for a few years as well.

As far as Disposable, that's a good point.  LA here is worth presently about a 3rd to quarter of it's purchase price as scrap which is also a factor in being better bang for the buck over lipo .  There are limited lipo recycling facilities at this time, more in some countries than others but some places are already talking disposal fees for these batteries due to their Toxic nature.  LA can be recycled at any scrap yard, not many places relatively will take lipo.

The caveat is only china is making them.

Bingo and as you allude to, the quality is HIGHLY suspect.  I see most of the fanbois on solar and RV forums are all over the cheap, 2nd quality cells and the outcomes with them are hit and miss at best. If you miss, it's a lot of money down the drain or a long downtime and more cost to get a replacement... which will then never balance with the rest of the pack due to age alone.

Tesla is currently getting them from china, but Tesla is also in the process of build a US plant to make these! Question is, can anyone in the public get these from Tesla, and will Tesla's prices be reasonable and affordable?

Tesla and other car manufacturers are saying and have been for some time that supply of batteries is both their biggest limitation, headache and expense in the vehicles.  If they can't get enough to satisfy their own needs (Powerwalls were halted from production for many months because of Cell shortages) They certainly won't be offering them to the public to compete with their own products and if they did, they would certainly not be cheap.  NOTHING with Tesla ever is and they would put huge markup on anything with their name attached anyway.

China has very dicey quality issues, some times you can get good stuff, sometimes really bad stuff and you never know which on any particular order.  Also, individuals have no market leverage when ordering from china and may have difficulty in correcting any quality complaints.

Agreed but this should have been your preface paragraph because it' is the relevant and over riding thing to everything else you said.
what good is cheap and whatever else benefit if it's unreliable or short lived?

All this " In the future" stuff is all well and good to say something will improve but it in effect never comes about because then something new comes along and it's back to square 1.
These Lipo technology's are a prime example. Every time they change the formulation  it's back to the beginning again. No one knows how they will hold up in 3-5-10 years time and what the last formulation did is irrelevant because this one is different and unknown.

La OTOH being old fashioned and untrendy and heavy and bulky and all that IS well proven, known and understood.  I know people personally that have had over 15 years out of proper traction batteries.  I asked a Client of mine about the  La " Maintenance Myth. He said he shuffles down the shed every 3 Months or so to put a bit of water in the automatic watering system and make sure the rats haven't  done anything. He says a guy comes out every 12 Months, checks the gravity of the cells, removes, greases and replaces the leads and wipes them down with a rag to get the dust off and make them look pretty again. 

He's been running his farm off grid for nearly 50 years and figures on 2-3 Inverters per set of batteries. He ran a Moffit Generator  and then went to panels in the very early 80's.

I hear lots of people going on about " Maintenance"  Like it's an endless chore yet there is nothing like the time needed on them that people spend taking the trash cans out and brining them back in every week but no one sees that as some great hardship like they make out checking battery's every moth or 3 is.

Waste Vegetable Oil / Re: Thank you
« on: September 21, 2021, 10:47:31 AM »

Seems in another thread here someone wrote a post that was well regarded about using  oil for fuel in engines.  Does anyone know where I could get in touch with them anywhere else as they don't seem to post here any more?

Changfa Engines / Re: 165F engines back on Ebay
« on: September 21, 2021, 10:20:14 AM »

I have a couple. The only problem with them is like all china engines they are mechanically noisy enough to wake the dead.

Listeroid Engines / Re: Ashwamegh cooling ..part 2
« on: September 15, 2021, 12:22:46 PM »

Just a comment - folks who work on water-cooling heat-exchangers and the like will tell you that more is not better.  There's an optimum rate at which water flowing over surfaces can take heat away from them and increasing that flow can reduce the efficiency of the process rather than improve it? 

That would be applicable in a high power situation where surface area in the engine was limited  with a high thermal load per Sq in of water jacket area.  In engines like this which are large bore, low power, It's pretty much laughable to even worry about it.

What is this, a 2 Lt or so engine doing sub 20 HP?  You could hook the engine up to a fire Hydrant and blast the water though fast as it would go and still not going to make a shred of difference.... only to overcool it.

Everything else / Re: Bad Solar Panel
« on: September 15, 2021, 12:11:16 PM »
I have been working in the solar game for some years now. The above poster is entirely correct.  Shorting a panels is insignificant to them.  The way they work, a dead short actually means they are generating less power through being off their Curve than under full load on it.

Wether the short caused the panel to become faulty or not, either way you were sold a dud and should return it for warranty.  Don't touch it, don't give them any opportunity to BS you by telling them it was connected when you got it, just tell them you took it out the box and it was DOA.  The only come back they could have is if the thing was shattered and as I presume it's not, they have no option but to replace it.

Changfa Engines / Re: 186f 10hp diesels for sale on ebay. How?
« on: September 03, 2021, 12:10:01 AM »

Always seemed laughable to me you can own an AR15 or walk around with a Pistol in your jacket in the US yet a small Diesel engine is too dangerous for private citizens to have and make electricity or pump water or plough a garden with.

Pages: [1] 2