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ICC
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# Posted: 16 Nov 2021 14:27
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Quoting: gcrank1 run the gen Id do the same thing, asap in the morning then let my array do absortion thru the day.
That is the best way. Use a generator for bulk charging to get the most out of the gasoline. Even with an inverter genike the EU Honda's. Absorb takes a long time for gasoline burning.
There are charts or tables available online for capacity reduction vs temperaure. You could use one to help understand things.
Batteries do create heat during the discharge; that comes from the chemical reaction that releases the chemically stored energy in the form of electricity. (That apies to lithium batteries too) So, in use, the batteries may be warmer than you think. OTOH, the mass of the batteries can make the batteries stay colder than the ambient sir temperature. An insulated but vented box can help regulate battery temperature.
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bc thunder
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# Posted: 16 Nov 2021 16:08
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I do have them in an insulated box, beter than nothing, but ai dought you'll fry an egg on them.
I have those temp charts, and all the other charts, and fomulas you guys have sent my way. My comp screen is litered with screen shots lol.
I don't mind running the gen in the morning, I just thought low fla batts could freeze over night? We are not there yet , but -30c is not freak weather here by ant means.
My rough math says I should be getting 10.5 watt hrs:
IF the batteries are operating at 70% (hydrometer)
And the temp is causing another 30% loss (-4c)
And my usage with idle draw is 150watts
And if 100% full charged
And run down to exactly 50%
I might get 8hrs, that is in the ball park.
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gcrank1
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# Posted: 16 Nov 2021 16:18
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The way you've been going I dont think your bats have been getting far into the absorption stage, which they need to do. It takes the longest after the initial bulk charge.
What is actually running all night?
Or maybe better, what is running from dark until bed?
Then what until you get up?
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bc thunder
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# Posted: 16 Nov 2021 16:34
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Internet hooked somtimes to tv, from dark till 9;00ish (3hrs@105W)
Turn off inverter (0w)
5;00am turn on internet only till daylight (3hrs@80w)
Not alot of sun here lately, probably not much till Jan.
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gcrank1
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# Posted: 16 Nov 2021 17:43
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So, 3hr @ 105w = 315w
and 3hr @ 80w = 240w
Total 555w / 24v = 23.125amp, rd up to 25amps per night for good measure, probably even 30.
Pretty minimal, should be well within what a decent 100ah battery can handle; ie, my target is 25-30% use.
Unless all ya got is a weak bat-bank with 25-35amps usable left in it.....then its dead.
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gcrank1
Member
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# Posted: 22 Nov 2021 15:58
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Hey BCT, are you still out there?
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bc thunder
Member
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# Posted: 22 Nov 2021 17:38
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Hey GC
I'm running the generator 2.5 hrs in the morning.
Then with some help from the sun, I can get by reasonably well, (being modest with consumption) till about 7:00 taking it down to about 60%/65%.
Then run the generator another 2.5hrs before bed.
Late spring I'll look to upgrade the whole system......
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gcrank1
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# Posted: 23 Nov 2021 09:46 - Edited by: gcrank1
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If Ive got this figured right, the amps charge (and the load) gets divided among the bats in the bank that are parallel; ie, 20a charge into 2 'quads' of series 6v = 24v each quad, wired parallel means 10a per quad. That is only at peak, as the charger cuts back it lowers to about a trickle charge.
Since your bat-bank apparently isnt getting really recharged on a regular basis you dont have much ah's in storage to draw from.
Wonder if it might actually charge better if you only use 1 of the 2 quads so those bats are getting the full amps charge in all those hours of gen running? In my thinking that might increase your usable amp hours.
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Brettny
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# Posted: 23 Nov 2021 09:57
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Quoting: bc thunder Late spring I'll look to upgrade the whole system.....
Add more batteries in the mean time. More pannels will also help.
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gcrank1
Member
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# Posted: 23 Nov 2021 10:12
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Brett, he's kinda caught between a rock and a hard place. His array cant keep his 8x6v bats charged as is (series/parallel for 24v) so more bats wont help.
More array might (he is full-time off-grid in Canada) but he got pretty much tapped out building this system.
The gen is the last resort and (imo) isn't getting much, if at all, past bulk charging so they are never getting well into absorb.
Basically he is running off the surface charge, and his use demands are relatively low.
Struggling and there is a lot of winter left.
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ICC
Member
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# Posted: 23 Nov 2021 11:11
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Quoting: Brettny Add more batteries in the mean time.
that would be a poor choice IMO, because they are FLA and as gcrank1 noted they likely are not getting fully charged as is. But this is one of those "rock and a hard place" things.
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bc thunder
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# Posted: 23 Nov 2021 15:32
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Can the load test be good, but the hydrometer show low batteries @ 75% or so???
Finally got ahold of the battery store, he thinks if they load test fine, they are good.
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bc thunder
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# Posted: 23 Nov 2021 15:38
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GC I catch your drift on the 1 string thing. I'll try that starting tomorrow.
I can turn up the charge rate (60a at the moment) goes to 100a
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Brettny
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# Posted: 23 Nov 2021 15:41
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Adding more batteries can give you more capacity. So longer run times between the generator but will need to run longer. The other though is with more useable capacity you draw the batteries down less..thus they actualy may have life left in late spring.
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gcrank1
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# Posted: 23 Nov 2021 15:59 - Edited by: gcrank1
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Batteries are rated by their manufacturer for a certain charge rate that you should not exceed. Ive not had 6v golf cart bats to build a bank from but what I said is pertinent to all batteries afaik.
I found online the recommendation for FLA GC bats of a 'c rate' (charge) of 0.1- 0.15 generically, Trojan specific no more than 0.13. That is, your battery AH rating times those factors is how much amps charge (or discharge) the battery can handle.
Hopefully someone here with a GC bank can be more definitive to your case.
As a reminder to all, BCT has 8 x 6v gc bats series wired to make two 24v 'quads', those paralleled to dbl the ah's. The bats were new about early last Sept?
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ICC
Member
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# Posted: 23 Nov 2021 18:06
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Here are my thoughts on why I recommend not adding to this bank that is in service.
1. It is not just that we would be adding a newer batch to an older batch. It is that we would be adding batteries manufactured from a different batch of lead plates. The lead composition can vary between batches. A slightly different composition may result in a slightly different internal battery resistance between the lead batches. Different internal resistance can lead to one discharging or recharging faster than the others. That can lead to problems down the road.
2. It is often said that new solar users will make some mistakes and ruin their first set of batteries. I do not believe that is always the case. I have seen a user whose first set if FLA GC-2's made it into the 9th year. However, this set of batteries could be an example that does fall into the category of being a "learner set".
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ICC
Member
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# Posted: 23 Nov 2021 18:08
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10 to 13% of the 20 hour rated capacity is a good maximum to use for everyday long term use
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bc thunder
Member
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# Posted: 23 Nov 2021 18:28
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I don't mind them being a learner set, but I'm still not sure if they need longer on the generator than a 5/6 hr bulk charge? Or, are they bad batteries, as the 70% hydrometer seems to indicate?
No mater what I do, I come away just as confused.
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ICC
Member
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# Posted: 23 Nov 2021 18:40
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Quoting: bc thunder Can the load test be good, but the hydrometer show low batteries @ 75% or so???
A battery load test shows whether or not the battery can produce the rated amps it should be capable of delivering. The load test does not indicate the state of the charge. A hydrometer, when used correctly, will indicate the state of charge.
A good battery could deliver its rating when not fully charged. A battery that looks to be fully charged by the hydrometer could fail a load test because of hidden internal plate damage.
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bc thunder
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# Posted: 23 Nov 2021 19:04
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Sorry ICC, I,m still not clear.
I took theses batteries back to the dealer, they load tested good. They sent me home with the same batteries. Is it possible they pass the load test, but not the hydrometer test?
I,m going back to see them tomorrow, and want to be sure I know what I'm talking about......
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gcrank1
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# Posted: 23 Nov 2021 19:25 - Edited by: gcrank1
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Imo the 'load test' is a quick & dirty way to eliminate bad bats right off. Those that pass should then be hydrometer tested.
The results of both those tests should be able to be done at any reputable dealer.
Any results of both those tests should be able to be interpreted and explained by dealer as relates to your issues.
That you are not able to get meaningful ah's out after hours upon hours of charging is also part of the 'battery' performance testing and analysis. Im curious how your dealer can explain that.
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bc thunder
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# Posted: 23 Nov 2021 19:56
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I should have 4 new batteries tommorw.
I think they make you jump threw hoops to weed out the warrenty abusers.
I will let you know how I get on..........
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Brettny
Member
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# Posted: 24 Nov 2021 06:00
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Quoting: gcrank1 found online the recommendation for FLA GC bats of a 'c rate' (charge) of 0.1- 0.15 generically, Trojan specific no more than 0.13. That is, your battery AH rating times those factors is how much amps charge (or discharge) the battery can handle.
I guess I dont totally understand this. 0.13 x 205 (for a typical gc2 battery) comes out to about 26a that one battery can charge at. So in BC case a 30a charger would be for 4 in series? If that's correct my 3 strings could take double the amps I'm putting into them.
When I built my bank with 2s2p I quickly realized I was at the edge of its capacity so added another string for 2s3p a few months later. Granted I dont live there so they prob had 3-4 cycles on them and sit at fully charged for weeks on end. I guess the real test is when I go back in the spring and there still charged. I left the system on with the inverter off.
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ICC
Member
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# Posted: 24 Nov 2021 08:43
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Quoting: Brettny So in BC case a 30a charger would be for 4 in series?
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gcrank1
Member
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# Posted: 24 Nov 2021 10:38
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If you did not discon the inverter it may have an idle draw all the time even if 'shut off'.
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ICC
Member
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# Posted: 24 Nov 2021 11:18
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Quoting: gcrank1 If you did not discon the inverter it may have an idle draw all the time even if 'shut off'.
Very good thing to remember. That is why I have a disconnect breaker (big DC one) in the + cable that feeds the inverter. I pull that when I leave the cabin for an extended period of time. OTOH, if the solar is maintaining the charge daily it is not a big deal in many cases.
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bc thunder
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# Posted: 25 Nov 2021 11:49
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Still same batteries lol
I have the strings isolated.
One string on trickle charger (2x12 in s) says they are charged. No recovery app, just trickle. Should I leave them, or try them out???
The hooked up to solar string, charged them last night with the Honda over 8hrs, got 50 mins out odf them to 50%. That seems even worse than I thought. I'm hoping I have somehow never had the string hooked up by itself. Maybe (lol) this string is the big problem.
fingers crossed
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bc thunder
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# Posted: 25 Nov 2021 11:50
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About 3hrs now on trickle.
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gcrank1
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# Posted: 25 Nov 2021 12:09 - Edited by: gcrank1
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You NEED way more than a trickle charge!
A trickle charger is intended to keep a fully charge battery 'topped up' Not to charge a depleted battery (that would take forever).
Thought you have a charger with more beans than that?
And just to check, your charger is a 24v output, right?
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Brettny
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# Posted: 25 Nov 2021 12:49
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Quoting: bc thunder The hooked up to solar string, charged them last night with the Honda over 8hrs, got 50 mins out odf them to 50%. That seems ev
You charged 4 gc2 at 30a for 8hr and only got them to 50%? Something seams wrong here.
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