Help with lead acid.

[backyardshane]

I bought 2 new 6v 215 ah lead acid batteries for a motorhome and left something on running them down to 3v. are they ruined? it only happened once and im not sure if they recharged because its parked at a recreation property and i havent been back.

 

[Alphacarina]

If you caught it quickly and they didn't sit for a day or two (or more) at 3 volts, they're probably not totally ruined, but you sure took lots of life out of them no matter what. They should recharge, but they probably would not pass a 215 ah test any longer. If they sat for a week or two deeply discharged, they prognosis isn't very good. A full recharge and then a capacity test will tell you where you stand.

The rating on Golf Cart batteries is usually done over 20 hours - They would supply 10.75 amps for 20 hours (before going dead, which you don't want to do) hence the 215 ah rating. Fully recharge them, put a 10 amp load on them and see how many hours it takes for you to get them down to 12 volts - That should take around 10 hours (50% DOD) so if you test and it only takes 5 hours, then they've lost half their capacity. Hopefully you'll get better results than that

Don

 

[Tecnodave]

Charge them very slowly, you will probably be able to recover them. One of my battery banks were recovered on the way to the recyclers, a brand new set of Rolls-Surette S-530 L-16’s we’re down to .05 volts for the set. I connected 4 “12 Volt“ solar panels in series to the stack of 4 batteries and left them alone to trickle charge from the 84 volts, 3.15 amps coming from the Siemens SM-50 36 cell solar panels......no controller....no diode...directly connected. In 30 days they were at 24.0 volts, then I connected MidNite Beta Kid number 1 to all 4 in series, several days later at 28.8 volts and 1.320 s.g. I’m still using these batteries. They came out the door at Rolls Surette in June 1995! 25 years old and still at full capacity......Yes I’m still into FLA batteries, have you ever heard of anyone getting that kind of life out of a battery set?......I apprenticed at Alaska Husky Battery in 1963.....they build very hot batteries that will start your car at 70 below zero......unfortunately the Employment Prevention Agency ran Alaska Husky battery out of the USA.....They are now based in Moscow, Russia where they still build the “Alaska Husky Battery” which is now used in the Russian Artic.

Charge very slowly.....don’t push them.....mine took several weeks to respond very slowly.....

 

[Bleedingblue]

I bought 2 new 6v 215 ah lead acid batteries for a motorhome and left something on running them down to 3v. are they ruined? it only happened once and im not sure if they recharged because its parked at a recreation property and i havent been back.

I'm not sure what your setup is, need more info. I use to have trojan L16 370AH and had 24 of em. I ran those down a few times to where I come home and the inverter was shut off. It come back just fine.
But I've never heard of someone running a battery down to 3 Volt, how is that possible? Does your inverter not have a shut off point? Are you running a 6 volt system?

 

[backyardshane]

I'm not sure what your setup is, need more info. I use to have trojan L16 370AH and had 24 of em. I ran those down a few times to where I come home and the inverter was shut off. It come back just fine.
But I've never heard of someone running a battery down to 3 Volt, how is that possible? Does your inverter not have a shut off point? Are you running a 6 volt system?

i dont have solar or shore power and i left the heater on. im going to put solar on this week end and im just hoping the batteries are ok.

 

[Alphacarina]

. . . . have you ever heard of anyone getting that kind of life out of a battery set?

I've heard similar stories from people who paid Rolls-Surette prices for batteries, but you won't get that sort of service from batteries made by those who sell at bargain basement prices. I got more than 10 years of service from my four Trojan L-16 batteries on my sailboat and they were still going strong when I sold the boat - They didn't last too much longer though. I know the guy I sold it to very well and he couldn't be bothered to even check the water level, much less ensure they were properly floated when not in use

You really can't compare a Rolls-Surrette L-16 to an ordinary golf cart battery when it comes to recovering from a deep discharge - You do get what you pay for . . . . most of the time

Don

 

[Alphacarina]

i dont have solar or shore power and i left the heater on. im going to put solar on this week end and im just hoping the batteries are ok.

I think his point was, the inverter should have shut off the load way before the batteries got down to 3 volts. You must have had some other load (a DC light maybe?) that didn't automatically shut off

Don

 

[boondox]

Are these flooded, AGM or sealed? If flooded I would give them a good EQ charge after you charge them normally.

 

[Tecnodave]

@Alphacarina

I paid scrap price $20.00 for my Rolls-Surette set as they were given up by the former owner who paid >$30,000 for solar equipment an never installed it and left everything in the shed including a mint Trace 4024 inverter, I bought the brand new, in box solar panels at .25/watt and am still using them (Sharp NE-170).........it’s all in what you know....

 

[backyardshane]

I think his point was, the inverter should have shut off the load way before the batteries got down to 3 volts. You must have had some other load (a DC light maybe?) that didn't automatically shut off

Don

i left the furnace on and parked it. it wasnt hooked to any charging method at all so when i came back 4 days latter they were dead so i plugged it into a generator for about 9 hours and they took a charge but i worry about capacity. im putting solar on this weekend. hoping for the best

 

[OnTheRoadAgain]

4 days on less than 50% charge is likely to have caused some sulfation and hardening. How much is anyone's guess.

A good capacity test is really the only way to determine where they are now.

Catching deeply discharged lead acid batteries quickly is key to saving them. Sometimes with fresh (soft) sulfation, a charge to 15 or 16v can remove the sulfation but then you run the risk of plate damage so it's a gambit. Some desulfating chargers can help remove some of the soft sulfation if used early enough.

Hindsight is always 20/20 but some kind of timer on that heater might help?

 

[Bleedingblue]

i dont have solar or shore power and i left the heater on. im going to put solar on this week end and im just hoping the batteries are ok.

If it is a deep cycle battery it should come back no problem. Just use a trickle charger

 

[OnTheRoadAgain]

...............

 

[Alphacarina]

If it is a deep cycle battery it should come back no problem. Just use a trickle charger

Depends on what you mean by 'come back' - True, they will most likely recharge and hold a charge, but they will never be 215 ah batteries again. They were more deeply discharged than they were ever designed to be and worse yet, they were left in that state for 4 days. If he's lucky, he's probably lost only 30% or so of their storage capacity which I would not say is 'no problem'. He likely paid around $300 for the pair and now he's 'lost' about a hundred bucks plus they're not going to last him 5 or 6 years like they should have. He'll be replacing them sooner than planned

Don

 

[Bleedingblue]

Depends on what you mean by 'come back' - True, they will most likely recharge and hold a charge, but they will never be 215 ah batteries again. They were more deeply discharged than they were ever designed to be and worse yet, they were left in that state for 4 days. If he's lucky, he's probably lost only 30% or so of their storage capacity which I would not say is 'no problem'. He likely paid around $300 for the pair and now he's 'lost' about a hundred bucks plus they're not going to last him 5 or 6 years like they should have. He'll be replacing them sooner than planned

Don

Well with lead acid you are never gonna use 100% of the battery with mine I pretty much only used 30% of them.
When fully charged they always settled down to around 80% and then id use em to around 50%.

 

[mike95490]

At 3V, some cells have been reversed polarized, not good. You may be able to get them charged somewhat, but you have lost a lot of capacity and lifetime.
Be glad it was not an expensive Li battery !!