Classic charging a 42V battery bank

[SolarMusher]

Hi all,
One of my x16 6V L16 is going to die early  . Actually my batt system is 48V/830AH two strings, 5 years old, Interstate stuff..., so I could re-wire this bank with just one string x8/6V 415AH and keep the actual 48V settings. But I'm afraid that these 415AH might be not enough to run the loads I need. The Magnum inverter could still work in the 36/67V range but I wonder if a Classic could charge a 42V battery bank without problem? A 42V/830AH battery bank would still be around 35kw and might be a good capacity/option for the next two years.
Any thought appreciated,
Erik

[Halfcrazy]

Yes the classic will do just fine with that. Simply set it for 48v nominal and then lower the set points accordingly.

Ryan

[SolarMusher]

Good to know that!
Thanks  a lot Ryan.
Erik

[dbcollen]

A 42V/830AH battery bank would still be around 35kw 
Erik

Just a quick note from the pedants, while you may actually be able to get 35kw from those batteries for a short time, the capacity is 35kwH. (kilowatt HOURS)

[dgd]

Erik,
why not just get a replacement, new or used L16, and replace the dud?  Better just to keep the bank at 48V
dgd

[SolarMusher]

Erik,
why not just get a replacement, new or used L16, and replace the dud?  Better just to keep the bank at 48V
dgd

Hello David,
Because three years ago, I had two cells that were leaking and had to change for two new one (the bank was only two years old...), but when I wired these batteries I saw that they were not exactly the same (UL16HC VS UL16HCS). Same brand, same voltage, same capacity but SG was in the 1.300 on both new batts. I think that interstate replaced the old UL16HC with the UL16HCS.
Three years later, all my 14x UL16HC cells are 1.255 max when 100% SOC with 1% end current at +10°C (not great), except one cell that is 1.220/30. The two UL16HCS still rise at 1.290/1.300.
No matter EQ voltage or length, SG is steady in the 1.250 range for all cells except this weak cell.
Another problem is that I need a small step-down converter 48/28V to power fridge and freezer and this converter have a LBCO at 44Vdc, with a 42Vdc bank I could not run this fridge and freezer  .
I'm afraid that the only choice I'll have would be just one 48V string with the stronger old batts.
You can easily guess that my next bank choice will not be with Interstate .
Erik

[dgd]

Hi Erik,

I see why you are thinking just one 48V string,  but if it was me I would just get another HCS after the suspect HC gets too forgetful.
I also would have expected L16 to last longer than 5 years,  The leakers were warranty replacements?
Any idea what the problem is with the suspect L16?  I assume its not sulphated as other HC are good.   It may an idea to get it  to a battery reconditioner and see what they say.

Off topic,but..
I had 4 endurant L16s, ex forklift, that were given to me as worn out. The recon people treated them with some additive, overcharged them several times, did high and low freq AC while charging. They are still good after 2 years,they even gave me a 1 year warranty 

dgd

[SolarMusher]

Hi Erik,

I see why you are thinking just one 48V string,  but if it was me I would just get another HCS after the suspect HC gets too forgetful.
I also would have expected L16 to last longer than 5 years,  The leakers were warranty replacements?
Any idea what the problem is with the suspect L16?  I assume its not sulphated as other HC are good.   It may an idea to get it  to a battery reconditioner and see what they say.

Off topic,but..
I had 4 endurant L16s, ex forklift, that were given to me as worn out. The recon people treated them with some additive, overcharged them several times, did high and low freq AC while charging. They are still good after 2 years,they even gave me a 1 year warranty 

dgd

David,
No, unfortunately these batteries were out of warranty (one year). I think SG problem came from the two "new" batts, to be sure I would need to wire a single string with the old ones only and EQ for a long time, I'm pretty sure that I could rise SG to 1.275 but that wouldn't solve it all. Another idea could be in the same time to buy a little 12V iota charger and try to EQ/recover the bad one , it should be more efficient on 6 cells only rather than 24 or 48 cells.
I would not like to spend much more money on these batteries, I believe that I'll have to change the whole pack in the next two years. If only they could last two years more it would be great, it was my mistake to buy this brand. When I've bought this off-grid place, it costed me an arm and the budget for the system was too limited at the end...
I would prefer to wait and buy 16x Trojan 370Ah or Rolls 350Ah or at worst 8x Rolls 450Ah.
Choosing a new battery bank is not simple! Rolls had several problems and Trojan is not really better, they are all sweeper batteries which want to be discharged/charged on the same day. Maybe a good choice (compromise  ) would be the cheap Trojan 6V L16AC 370Ah if I could get it with 2 years warranty replacement  . With all the dogs I still have, I'm not rich enough to buy the 6V 370Ah Trojan RE serie that I would like, they are too much expensive here in Canada.
I have a Trojan supplier who could deliver his batteries with the rated SG, at least it's a good begining  .
Erik