Battery Charging Problem

[fullraph]

Hi

Few days ago, I used one of my deep cycle battery with a 400 watts inverter to run the TV and small appliances during a power outage. The battery worked awesome as it was suposed to. When the power got restored, I hooked the battery to a motomaster 12 volt charger on the 2 amps circuit and let it charge for about 12 hours. After that, I performed a volt test on the battery but it was dropping dramatically fast! It lost about 0.01 volt by second and it stoped dropping after few days at about 6 volts... What is happening? I never had such a problem with a battery.
By the way, the battery is a pretty common model, an Interstate HD24-DP

Thanks

[sabray]

Your battery is fully discharged and need to be charged fully. 2 amps for a few hours wont get it restored. Batteries really do not like being discharged that far. Grand Ma says bahha boica. I think you get a real charger and burn in some amps

[fullraph]

I have another charger that can put out 75 amp on the booster setting but, it will overheat the battery really quick I think. The charger I used can put out 2 and 12 amps, how long should I let it on the 12 amps setting?

[sailorchic34]

Assuming thats a group 24 battery, it has an amp capacity of about 85 amps. What was the voltage after the first charge. A battery will loose the surface charge quickly but should hold at 12.7 -12.8V with no load and about a 0.1V no load loss a day.

Sort of sounds like the battery developed a warped plate and is shorting out. If thats the case its time for a new battery.

Try charging at 12amps for 6-8 hours. The battery will not take 12amps all that time. As the internal resistance goes up the charge rate decreases.

[fullraph]

when I unplugged the charger after 12 hour of charging, the voltage was about 12,60 volts and right away it started decrasing, 12,59 -> 12,58 -> 12,57... About 0,01 volt by second.

[senormechanico]

You're getting close.
If it was mine, I'd leave it on the high setting for 24 hours.
Let it sit for a day and THEN measure it.
It should be 12.6 volts.
If it's less than about 12.3 or thereabouts, you probably have a weak battery.

[sailorchic34]

Right, charge it at the higher amperage for a good while and let it set disconnected till the next day. If the battery voltage is still way low, <12.00 volts then you have a bad cell or cells. That is one or more plates is shorted to adjacent plate(s) and its self discharging. New battery time in other words.

The voltage dropping slowly like you indicated is to me anyway a sign that a cell in the battery is bad. Classic example

[fullraph]

Thanks for you answers. I just checked it, it was a bit low on liquid so I filled it up with distilled water. I hoocked it on the charger, i'll check it tomorrow.

[Maine Sail]

Originally Posted by sailorchic34

A battery will loose the surface charge quickly but should hold at 12.7 -12.8V with no load and about a 0.1V no load loss a day.

At room temps a battery can take 12-24 hours to reach a resting state before an open circuit voltage reading is going to be accurate.

0.1V per day would be an approximate capacity loss per day of about 10% meaning that in 5 days with no charge your batteries would beat at 50% SOC.. My batts have been sitting now for roughly a month, not on charge, and as if yesterday were still at 12.71V.. I suspect you did not not mean 0.1V per day??

A battery dropping to 6V, as the OP's battery is doing, is not a good sign..

Battery SOC at Resting Voltage and 80f (Source Trojan Battery)
100% = 12.73

90% = 12.62

80% = 12.50

70% = 12.37

60% = 12.24

50% = 12.10

40% = 11.96

30% = 11.81

20% = 11.66

10% = 11.51

[sailorchic34]

Right.. It's 1% self discharge a day or about 0.01V, not 0.1V. darn decimal place....Blonde happens!