problem concerning battery discharge

[snake21]

hello friends,
got a small problem.please help me out of this.i have a 200a 12v car battery which was kept in my store for about 4 month.after 4 month,i checked the voltage,i was around 6.6v.i immediately connected my small wind turbine9(ametek 38vdc) to it in trying to raise the voltage.after 2 days of charging,the voltage reached 11.8v which is i think is normal.i have a small switch where i used to charge a primary battery and a secondary battery with my turbine

everyday,i use my turbine to charge both the primary and secondary battery.but some days before i noticed that in 6 hours,there was a drop in that car battery voltage from 11.8v to 10.1v.i thought that maybe some more charging was required but even if my with turbine is hooked to it for 2 days,the voltage drops to 10.1 volts.i have checked if the switch was defective thus connecting both batteries,but the switch is fine.i have been using this system for 2 month but there was no such problem

and also,i have never used the battery before.

is there a solution to solve the problem please?thx

[joestue]

you need to hook that battery up to a charger and get the voltage all the way up to 16 volts for some time, and add water as needed.

was the battery fully charged 4 months ago? if so it should not have discharged completely

[snake21]

no,the battery was about 12.2v 4 month ago.it is a serious matter?

thanks

[bj]

  Are the caps of the type that allow you to do S.G. on each cell?  Might give a clue to what is happening with it.  I'd be tempted to
give it a hard nudge @ 16V as well.

[snake21]

hello bj.i am sorry but i cant understand this part.can you plz elaborate?

Are the caps of the type that allow you to do S.G. on each cell?

i want to give that nudge too

thx

[mab]

all your voltages seem low; a fully charged car battery is usually >12.6v, although an old one can be lower.

no,the battery was about 12.2v 4 month ago.it is a serious matter?

yes. A battery should be stored fully charged, and ideally have a top up charge every couple of months.

As others have said you should give it a long slow charge up to 15-16v, then see what it does over the following few days - it should settle to a voltage above 12.6volts and stay there. If it falls to less than 11v it usually mean it's got one or more bad cells.

hello bj.i am sorry but i cant understand this part.can you plz elaborate?

Are the caps of the type that allow you to do S.G. on each cell?

The best way to understand the condition of a battery is to measure the specific gravity of each cell with a hyrdometer - to do this it needs to be a battery with liquid electrolyte (flooded) with removable caps that you can open to access it (most car batteries are this type), and not the 'sealed' type (gel / AGM).

mab

[bj]

   Mab pretty much covered it.