DC Charging with 16/1

[ronmar]

You should be able to run a lot more current into the batteries during the bulk charge..  They should be able to accept 25% of the 20 hour capacity in amps as long as the temp is kept under 125F.  So with 1100AH capacity, you should be ok to 275A with temperature monitoring.  But at 48V, that is 13KW, so you would need a little more HP to support this.  But it would shorten your charge times a little:)

[Incredilion]

Hey Bruce-
On the efficiency thing, from using 60 amps vs 100,it was me who measured it, by voltage, and measuring the amps it took to get there. Like i was saying, the forklife batts charge MUCH more efficiently by using a higher amperage, I confirmed it with a couple of manufacturers after the fact.
 What happened is when I first started charging them, with the 60 amps, it was taking a LOT more power than what I removed, by something like an additional 50% or so. I thought this was wrong, or I was doing something wrong, so I started digging into it, and lo & behold, both my battery guy AND the manufacturer said the same thing; "your charge rate is too low; it's inefficient".
I'm still plauying around with charge rates, etc, and spoke with the guy who designed the MARS motor today. I'm probably going to step up into the 1003 (Model) as it has a continuous rating of 200 amps, instead of the 100 on the motor I have now, so longe rlife, 2 sets of brushes, etc etc....ALWAYS more....
And thanks very much for the offer, I will take you up on it when I have time to breathe. I sell Prepper properties in North Idaho, you can IMAGINE what it's like here, after the election. I am a very busy person.

Ronmar, you're right on the money, the batts per manufacturer will take 260-280 amps, right at the 25% you spoke about, and if I could make 13KW I think I would...BUT I would then need (BIGGER cable, redesign again, ughhh.....) I think I'm good at the 100-150 Amp range, the Lister gets right around 1/2 gph right now, that seems good to me. It's running at a little below 800 RPM, and starts when the battery is low making about 6-6.5KW in terms of direct battery power, finsihes at about 3KW when they're topped off.

Again, thank you for the comments fellow, awesome to speak with people that understand this. Normally, I show people what's going on here & they think I'm some kind of genius, which is PATENTLY untrue. I meet people smarter than me every day, no doubt.
Chris

[ronmar]

As to the low current charge efficiency, I think large batteries are a little like heat exchangers IRT charging.  The chemical transfer(putting sulfur back into solution) at low current relies mainly on diffusion pressure.  The solution right next to the plates saturates with sulfur(surface charge) and the battery appears to be charged so energy flow into the battery decreases untill the dense solution diffuses into the weaker solution.  A heavier charge current causes turbulence which causes weak solution to be stirred into contact with the plates to be enrichened. The weaker the solution, the faster the transfer, so turbulence is a good thing...

Like a heat exchanger, the colder the solution placed in contact with the exchange surface, the faster the heat transfer, so turbulence is also a good thing. 

[Incredilion]

Buddy, you're WAY past me....very cool that you have a comprehension on this, Ronmar.

It is pretty amazing how much faster/how much pless overall power it takes to charge that puppy back up if I have more than 100 amps flowing to it.

[BruceM]

Thanks for the good info, Chris.  I really appreciate learning something new from you about forklift battery charging characteristics. Good luck your new higher capacity motor/generator  and also with the prepper sales!

Thanks also to Ron for the description of the physical action that explains the poor charge efficiency at 60 amps.

It's hard for me to get my head around these high currents, as with my modest 120VDC system I just don't have to deal with that, or the huge battery capacities.

[Incredilion]

Here's a little info:
Today, when I started charging, the batts were down to 54%, and that's on an 1105 AH battery @ 48VDC. So, in order to refill it amp to amp (which won't happen) I'd need to replace 508.3 amps overall.

It took a total of 609 to do it, so I was over by about 100 amps, or less than 20%.

IF I had done that with 60 amps, I guarantee you I'd have used every bit of 900 amps, so it just takes les overall power to make it happen.

And BTW, that recharge cost me 1.5 gallons, I LOVES me my lister....
Chris

[mobile_bob]

Chris

maybe its just that i am tired, dense or both, this evening

lets do the math

you put back ~600amp/hrs at ~55vdc (a bit more i know, but for the sake of discussion)

works out to a bit more than, lets see now  100amps at 55vdc is 5500watts, x 6 hours?
or 33kwatt/hrs?  on  a gallon and a half of fuel?

33/1.5= 22kw/hrs per gallon of fuel burned?

that is about 3 times more power per gallon,  than is typical of a listeroid,
so i am thinking i am missing something here.

maybe i need to sleep on it and take another look?

bob g

[Incredilion]

No problem, Bob.
Here's the story:
OK so today, I was using BOTH my grid power inverter charger, at about 60 amps, AND the Lister at between 125 amps or so when at the beginning of the charge, and finishing at around 3KW, or 3,000 watts (sorry I forgot about the inverter when I posted this). The Lister starts charging at around 6500 watts, and slowly comes back down to 3,000 watts at finish, maybe 3 hours later. So, that being the case, if you averaged it, I would be making about 4500 watts per hour, over a 3 hour period, or right around 13.5KW, total.

I made 609 amps at the house today, now, that being said, to really grab it all today, these things made power at my house today:
Windmill 130 amps
Grid       150 amps
solar         4 amps (RAINED/sleeted insanely all day...)
So; that's about 284 amps x let's say 55 (volts) =15.6KW
Then, I had 325 amps that came form the Lister over a 3 hour period.
55x324 amps hours=17.8KW.
So, the Lister made more power than I thought it did, over 3 hours it made 5,340 watts per hour on 1/2 gallon of fuel per hour.

Sounds right to me...I think?

Lemme know, Pal, if I'm wrong I'd rather know now than in TEOTWAWKI....
Chris

Now, my count was of pure AH installed in the battery....
IF I take 500 AH from the batery, and refill it (2) ways, here's how it'd go:
At 60 amps charging current, I would end up putting back somewhere in the 800-900 amp range.
If I put it back in using 100 amps plus charging current, it would take around 600.

[ronmar]

Well 4500W for 3 hours on 1.5 gallons falls very near to the dreaded listeroid 1/8 gallon per KW, per hour range:)

[Incredilion]

Hey Ronmar, I'm not familiar with this, but is thatthe deal, they're supposed to make a KW for every 1/8 gallon per hour, really?

If so, I gotta be doing something right?

I measured fuel going into the tank at right about 2 inches per gallon, so I used just over 3 inches today, and rand for 3 hours, from 10-1:00.

[mobile_bob]

ok, that explains it!

when i first read the report, i thought something was so obvious that i could not see it.

sometimes i will read right over a factor that changes the complexion of the story, and just can't see it no matter how many times i reread it.

gets worse when i am tired.

yes, as Ronmar noted, you look to be very nearly the 1/8 gallon per kwe generated, which is right where we would expect it to be. actually you are probably doing a bit better because of the fact you are making DC instead of AC power. 

the 8kwe generated per gallon comes from the members experience with listeroids driving ST generator heads, which of course are AC 120/240 units and don't have the rectifier losses that a DC alternator would have to account for.  it looks like the pm generators magnet fields offset the losses of the rectifier, or nearly so, for all practical purposes.

sounds like you are definitely on the right track.

bob g

[ronmar]

Hey Ronmar, I'm not familiar with this, but is thatthe deal, they're supposed to make a KW for every 1/8 gallon per hour, really?

If so, I gotta be doing something right?

I measured fuel going into the tank at right about 2 inches per gallon, so I used just over 3 inches today, and rand for 3 hours, from 10-1:00.

Like Bob said, a 6/1 with ST-5 typically does around 1/8 gal per KW/HR.  The higher the load the better it does as the price(in fuel) per KW is highest for the first KW generated on the ST(and most other excited generators).  It was also more efficient with higher operating temps.  Here is a consumption chart for my 6/1...

[Incredilion]

Thanks for an EXCELLENT chart, Ronmar.
What you are showing confirms about what I'm saying, I think. I know I'm doing/making about 4500 watts an ahour on average, no doubt at all, maybe a little more, and I'm real sure it's going through right at a half gallon an hour, straightaway.

[vtmetro]

This is the document I read which changed my mind a few years ago about deep cycling batteries from an economic efficiency point of view.
Note that isn't quite the same as extending the lifetime of a battery bank in terms of years.

The document was produced as an advisory by a boat refrigeration company for cruising boats for sizing battery banks. But I think it may be of interest to us as well. Or, at least, it was interesting to me.


http://www.pacificseabreeze.com/tech-library/batterysizing/1batcrg.htm

[Incredilion]

That was really interesting, VT. The ideas contained in it are a little different, but I think well thought out. They did say that:
"Likewise, using a 100 amp alternator to charge a battery bank with an acceptance rate of 240 amps is pointlessly slow and inefficient.  The goal is to get the output of your alternator (under actual charging conditions) to match the acceptance rate of your battery bank as closely as possible"
 Thats pretty close to the words I got when I spoke with the people frmo the battery manufacturers.
I'd realy like otknow how many AH I'm supposed to get in total form the batts, I know people that have been using the same batteries for literally 20 years & have no issue with them at all. Biggest thing is that you get the largest AH capacity you can, I think.

Thanks for the link, I'm going to print that & stick it in my archives.
Chris