Deep-Cycle Batteries

[quartersplash]

I have 4 trojan L-16 deep cycle batteries that are 3 years old, and only cycled for a 3 month trip and have been sitting for about 3 years, kept up to charge by the solar panels. Last week one of the guys left the inverter on with the charger on and ran the batteries down to 3.5 volts.....I have hooked up my small 10 amp charger to one set of batteries and have only been able to get them to come up to 10 volts. Is there anything that I can do to get them to come back?

[nonam]

I think you need to find a way to charge them to about 15 volts.Time is of the essence because the longer they remain at low volts the more sulphate will form.If its been a few days you may recover something but if its longer then they are probably dead.

[CSY Man]

Fill em up, then equialize them. Need strong charger to do that, but good for the batteries.

You should be able to get 7 years out of these batteries if you never run them dry or never go below 50% charge. (I know, the damage is done, but perhaps not fatal)

[marshmat]

The L16 shouldn't be too badly damaged by one over-discharge. It's a pretty robust battery.

Assuming you're running a 12 volt system, the manufacturer's spec sheet for that battery would suggest that you need to charge at 14.8 V, float charge at 13.2 V, and equalize at 15.5 V (assuming 25 Celsius ambient temperature).

I would suggest checking the water level in all cells, charging them properly (14.8 V, then 13.2 V, stop when the smart charger cuts off), then equalizing. A 10 amp all-purpose charger can't do this; you need a multi-stage one that's designed for high-current banks.

[quartersplash]

Thanks for the replies.
I am not sure that a good portable charger is available here but here are a couple of ideas....
I have 700 watts of solar panels and good sun here in Bahia de caraquez. Could I disconnect the solar panel regulator and put full charge to equalize the batteries? The only problem is they will charge at like 20 to 22 volts....
I also have a freedom 2500 inverter charger. And since the batteries were drained to 3.5 volts, the link 2000 has went nuts and I am not sure if it will allow me to turn the inverter charger on. Maybe somebody knows? I only have a honda 2000i generator to try and power it with, but may be able to borrow a larger generator.
Thanks for the help.

[nonam]

Yes,connect solar panels and disconnect at 15.5 volts

[nknowland]

After being gone for 4 months we noticed that our starting battery was not taking a charge and needed to be replaced after 1.5 years. We have four 2.5 year old Trojan T-105plus house batteries with a Xantrex Freedom Marine 25/Link 2000 that are not going to a full charge, despite filling with water 3 times and equalizing for ~4-5 hours twice in the past two months.

After 3 hours on a Honda 2000 the amp-hrs the house bank went from -125 to -55amp-hrs. Usually this would have taken them to nearly a full charge. This morning when I checked the batteries the water was ~.25 inches below the indicator line and all the cells at a specific gravity of ~1.260 with 11.45 volts and -110 amp-hrs. No plates have ever been exposed and usually take 1-2 oz. of water to top off every month or so.

Any suggestions?

[nknowland]

Just a quick note/ It appears the Link 2000 needed to be reset.... Measuring at the battery terminals I get 6.5 at rest and 7.1 when charging , which matches the amps charged and the amps measured at the charger and batteries. Hopefully problem resolved.