Hi all, my 100 ah battery has gone almost dead flat ( 4.04 v). I know they need to be hit with a good strong charge ala' HD battery and jumper leads, before the smaller chargers will take over.
I have a pair of battery clips that plug into the Anderson plug (which shows 12.4v) will that do it ??
Cheers DR.
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Karl Marx.."the masses are the asses" Groucho Marx.. "I never knew my brother Karl"
I have four 26Ah gel batteries. A bit over 13 volts probably a few days after they are charged (screenshot attached).
My Victron 10amp charger will charge at mid to high 13 volts at 10amps, as the batteries get closer to fully charged voltage will get up to 14.4 volts sometimes still at 10amps (should have bought a larger charger!), then the amps will drop gradually to zero over about an hour until fully charged. Then go to float. Then to storage.
My last gel batt., lasted 8 years, and the last 3 years, it was on 11.5 volts, got rid of it when it got down to 9 volts. It still ran everything at 11 volts for that time.
GEL batteries should be treated gently. Batteries with voltages as low as your one may be sulphated, to recover them you use a small current over a longer period of time (that goes for every type of lead-acid battery.) I think the problem you are having is that many battery chargers will not commence charging until their output terminals are over 7 or so volts. You need to use another battery and connect the batteries in parallel, connect your charger and when it starts disconnect the donor battery. For starters set your charger to the lowest charge voltage you can, do not increase it to a higher charge voltage to hurry the process up.
When batteries get a bit sad like yours, the lower the current the more likely you are to getting them back to full capacity. Way back, when I was dealing with batteries like are used in telephone exchanges, we would use a maximum current of 2 A until the batteries terminal voltage came up a bit.
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PeterD Nissan Navara D23 diesel auto, Spaceland pop-top Retired radio and electronics technician. NSW Central Coast.
GEL batteries should be treated gently. Batteries with voltages as low as your one may be sulphated, to recover them you use a small current over a longer period of time (that goes for every type of lead-acid battery.) I think the problem you are having is that many battery chargers will not commence charging until their output terminals are over 7 or so volts. You need to use another battery and connect the batteries in parallel, connect your charger and when it starts disconnect the donor battery. For starters set your charger to the lowest charge voltage you can, do not increase it to a higher charge voltage to hurry the process up.
When batteries get a bit sad like yours, the lower the current the more likely you are to getting them back to full capacity. Way back, when I was dealing with batteries like are used in telephone exchanges, we would use a maximum current of 2 A until the batteries terminal voltage came up a bit.
Hi
I would generally agree with this. Do not "hit it with a good strong charge".
Why is it so low ?? How long has it been excessively low ?? How old is it ? You might get it back if you treat it gently as Peter has indicated. IMHO.
Do not "hit it with a good strong charge". 
