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21
Everything else / Re: Solar Inverter - Load sensing
« Last post by glort on July 20, 2019, 12:59:25 AM »

 Frankly MPPT is a waste of circuitry and complexity for this application, and a simple DC solid state relay driven from a non-load carry thermostat would perform similarly.

Yep, that's what my first idea was based on. Use the thermo as a non load beading controller to drive a fet that does handle the load.  The thermo Board will be driven by a Little converter that will take high voltage DC and bring it back to 12V @ .5 a and that can drive the fet that is switching the the power from the panels and the cap. Divider to replace the thermo couple and run the power into a cap bank and switch that to the element with a fet.

Panels have some flexibility in them regards to the power point and I'm going to try 4v either side of their rated Pmax as I believe they will perform efficiently enough in that range and there will be variation anyway due to manufacturing tolerances. If I'm running 8 panels in series to get the voltage and power to where I want it, I'll get a fair voltage swing between  the on and off cycles to make  control easier and give the panels a decent but tight enough working range. The goal here is cheap and simple enough for a twit like me to make it work, not the sub watt efficiency an electronic genius like you have the knowledge to construct. I think this will work to a level where things like cloud and the amount of bird droppings will have more influence than the efficiency of the circuit design and if not, doesn't matter.
I'll be still getting a Hugely better efficiency out of something I can hash together for maybe $30 instead of the $300+ for a tekluck or similar.


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Your scheme will have the same limitation, Glort, in that 90V applied to a 230V, 4500 watt element (11.5 ohm) will only consume 704 watts. 

Geez, I hadn't even thought to work that out! Sometimes the obvious escapes me.
That is going to be so much more power than I need for the job in mind. I'll have to incorporate a thermo into that or I'll have a kettle in no time with the amount of water I want to heat.  Could knock the panels back but I'll leave them as 3 to allow for crappy weather and power in reserve.  This will mainly be a winter thing so in reality I'll probably be getting 1/3rd of that output but still plenty more power than I was thinking for some reason.  :-[

For doing a domestic heater I'll just increase the panel array and add some mosfets to carry the higher load. That will only be for the exercise as I have no need for that in reality with my present setup but If I can make it work I can do a vid for others whom may find it helpful.
Even at 700W, a small 125L heater unit could go from 40 to 70oC in 6 hours. if you had a series of 3 panels in 2 parallel arrays, you could get that 6 hours of 700W for a lot of the year. The limitation of the resistance of the element would mean you could throw more power from the panels at the controller without cooking it because the voltage will stop the element sucking more power than the 15A the controller in mind can handle.


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You must either increase panel voltage or use a DC-DC boost converter (or other DC-DC transformer based design) to raise the panel voltage to match heating element, or find a lower voltage, high wattage element.  Ohms law lets you calculate it.

Yep, don't want to add the converter so I'll use more panels and raise the voltage/ power and just use the controller to drive a fet on the high side.
There is a guy on YT that spouts a design he came up with that runs off 2 panels and has a voltage converter but the thing is only doing about 300W. He claims that is enough but then says hes only heating a 5 gallon tank.  Mrs would use that for the washing up! No way in hell I'd be living with 2 minute showers again.  I spend all day getting filthy and aching, I want a good long shower to get clean and take some of the ever increasing pains away.

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  Sadly it is now normal to have hobbyist design level switching power supplies in appliances of all sorts and this does not bode well for public health since conducted EMI goes back on all the home wiring.

I was thinking of you the other day Bruce.
Something the daughter brought home and plugged in the other end of the house and I could hear the EMI through my computer speakers.  It turned out to be the AC power supply. Once she took that off the thing was fine ( well not producing interference my computer speakers could pick up anyway)  and I got her to charge it from a USB source. I must have rubbed something off on her. She has this large battery bank for her phone and other things and has been taking that with her to work and charging it in the car on the way and back home. She seems chuffed she can charge it in the car for nothing and then charge all her devices from that.  Spose it's a lot better than all those converters she had power board full of in her room.
22
Changfa Engines / Re: New Watercooled Diesel Toys
« Last post by ajaffa1 on July 19, 2019, 11:42:45 PM »
Loving that recoil starter, do they make them in different sizes for larger/smaller engines?

Bob
23
Engines / Re: Lister ST1 becomes hard to hand crank.
« Last post by ajaffa1 on July 19, 2019, 11:32:30 PM »
Hi Wess123, I suspect that we need a little more information but the most likely cause of the problem you describe is that the decompressor lever is out of adjustment. (please see the attached Lister instruction manual page) It could be that the valves are out of adjustment and fouling on the top of the piston at top dead center.

You claim that it has never been overheated, difficult to do with an air cooled engine, unless what you have is an STW1 which is water cooled. Water cooled engines are easy to overheat, inadequate fluid/water pump/fan belts etc.

You do not specify what your engine is coupled to but the fault could be with the driven not the driver.

Other possibilities include fluid in the cylinder water/oil/diesel. Excessive carbon build up on top of the piston, this is common in engines that are only lightly loaded. dribbling a little water into the air intake when it is running and hot will usually clear all but the most suborn deposits.

Let us know what you discover.

Bob

24
Listeroid Engines / Re: oil sump intake screen blockage
« Last post by Hugh Conway on July 19, 2019, 10:41:51 PM »
Thanks Butch
I forgot!  :-X  ;)
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Changfa Engines / Re: New Watercooled Diesel Toys
« Last post by Tanman on July 19, 2019, 10:34:13 PM »
Maybe you could throw one of these on your new toy! https://www.youtube.com/watch?v=mhG6qqh2ooQ
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Changfa Engines / Re: 1115 build
« Last post by Tanman on July 19, 2019, 09:28:06 PM »
Thanks 38AC, I must be getting cold feet with the project lol, wondering if the thing is going to explode in my face after some moderate use and if I should have started with a listeroid instead for this project. I think I read somewhere that you had a machine of the same brand? Jiang Dong, if so, how has your experience been with that machine?
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If you are only charging batteries, I wouldn't be so quick to change it from a 3/1.  A 3/1 might be a better match for a battery charger.  Think about what your expected battery bank is going to be, and how many watts you are going to push into them. More charging time is spent on the tapering charge and you might be better off diesel engine life-wise going a bit slower. The alternative is AGMs, which will take massive current but no so much wet lead.  I never switched to AGM for my main 120V bank as the cost was just too high for somewhat increased life.  The better performance I don't need.  I don't do winter dark day generator charging anymore since increasing my PV from 800 to 2300W. 

On second thought those valves do look the same as 6/1 types.  We had one member (Starfire?) who had reported on modifying a 3/1 to a 6/1 and I vaguely recall the head is the same.

28
Everything else / Re: Solar Inverter - Load sensing
« Last post by BruceM on July 19, 2019, 09:02:20 PM »
The Techluck is only a DC PWM unit, with no voltage shifting ala boost converter, so wattage to element depends entirely on the panel array and element voltage.  Open circuit max PV voltage is 250V, and max operating PV voltage is 200V.   Frankly MPPT is a waste of circuitry and complexity for this application, and a simple DC solid state relay driven from a non-load carry thermostat would perform similarly and without any EMI, at a small fraction of the price.

Your scheme will have the same limitation, Glort, in that 90V applied to a 230V, 4500 watt element (11.5 ohm) will only consume 704 watts.  You must either increase panel voltage or use a DC-DC boost converter (or other DC-DC transformer based design) to raise the panel voltage to match heating element, or find a lower voltage, high wattage element.  Ohms law lets you calculate it.

Most cheap hard switching and badly designed devices make me cringe; EMC is typically ignored, the cables to the panels will likely obliterate radio reception in the home.  Sadly it is now normal to have hobbyist design level switching power supplies in appliances of all sorts and this does not bode well for public health since conducted EMI goes back on all the home wiring.  Our home's wiring is typically totally unshielded, thus acts as a radio transmitter for high frequencies and is literally wrapped around us as we sleep.  Switching supplies were unheard of in appliances and HVAC just 50 years ago, so now we are in the midst of a huge public health experiment; both wireless and EMI levels  in homes are now typically 100,000 times higher than 50 years ago.  Neurodegenerative diseases, autism and other chronic illnesses are on the rise.  Hmmm.



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I should have commented, yes, that is an odd-looking sleeve assembly . . .

There's still life in the barrel and the piston assy looks good - probably I can find someone with a 3/1 who can use them - and maybe the head, if that's what it is

Cheers
30
Hi Bruce

At the site where it is sitting there is work to be done supporting solar when the sun don't shine or when loads are high.  This is up at my Bay of Plenty "retirement plan" site.  Sounds grand but really just a paddock with a workshop & a shed and a spring-fed elevated water supply at 2 bar - plus it's sited in the "sunniest" part of NZ - so all-in-all a wonderful potential off-grid site

It's bolted down to a big 6" X 12" RSJ /I-beam frame on a concrete pad.  So I'd like to use the bottom end at least and, superficially, it feels OK (no movement to be felt leaning on the wheels or rattling the rod/big-end etc)

I have a good +40 thou barrel and I recently bought a new +40 thou piston assembly from England.  Plus I have an original CS 6/1 head with good-ish valves and seats - so those bits can go on.  The head has a glow plug in place of its COV valve so calculating squish to get the compression just right may be a bit of a trial-and-error

I can probably just put all those bits together for a good result.  There's a new Bosch/Mico pump & a new injector already there for it

I have a couple of monster (about 90A I think?) new Leece-Neville bus alternators that wouldn't take too much mounting, so it can make DC for batteries.  And I have a couple of 5kVA-ish heads - an ST clone and a nice Markon - either of which can potentially sit there and make some AC

Should I live long enough for the day to come that I have both time and money, I'd like to pour a bigger, deeper pad so that the "feet" of the I-beams are actually sunk into it and build a wee shed around it - but that's a fair way down the to-do list

I do have another good-runner 6/1 sitting in the yard at home doing nothing - but the things are heavy and it's 400Ks away; so I'm thinking to persevere with the bottom-end of the one that's already bolted down for the moment

The good thing about playing with the old motors is that I think one gets a bit of a feel for what is tolerable/acceptable wear/clearance etc on these forgiving old engines - partly by looking at the state of them as they are torn down and in which state they had presumably been running . . . and a feeling for just how simple it is to get them running OK-ish.  The devil will be in the detail of getting squishes just right, getting the governor linkages to make some sort of constant HZ - that sort of thing

Lots of good advice here in the WOK and elsewhere on all that stuff, of course

And, of course, every time I find an engine and take it to bits there are potentially a few "spares" to go on the shelf at worst - even if most of it is junk

Cheers
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