Battery Question

My "ideal" for a standard 2.75% antimony battery in long-term storage is to keep it at 40F, 13.6 volts constant, and then increase voltage to 15.5 once a month for one-half hour to stir the electrolyte.

Try to not place a flooded battery on a cold surface. More clearly, on a surface that is more than 20 to 30 degrees F cooler than air temperature. This encourages stratification of electrolyte.

Check the specific gravity after charging. If they compare well you should be fine.

Any time a FLA battery is even slightly discharged it will suffer sulfation. It is best to keep them on a battery maintainer to prevent this.

You did damage although minimal and you are unlikely to notice a difference in functionality. You did shorten both batteries lives by allowing them to sit in a partially charged state.

BTW a FLA will suffer less self-discharge at lower temperatures than in warm. Storing in a cool environment is a good thing.

I keep my spares out in the unheated shop through the winter. Check them about once a month but they usually are fine. What I don't do is let them sit on anything like a concrete floor. They sit up on a wooden bench. It's not really required anymore to keep them off the concrete to keep them from discharging but that's what my dad taught me and old habits die hard. The only reasons I keep them on a bench now is the concrete gets pretty cold and stays that way but the shop air at the bench level seldom gets that cold and for most of the winter (except for this year) stays just above freezing. They are also easier to check at bench level.

Thanks for replys,didnt want to install if harm was done to them. Wasn't sure if a couple months at 12.4 was harmful. Lesson learned instead of sitting them on cold concrete next off season,will keep them in a warm area and recharge mid winter.

I've had some DC 12v batteries than when fully charged and rested would read 12.8v

I've had others that would read 12.6v under the same circumstance.

I have an AGM battery that reads 13.07 volts when rested and fully charged.

These " universal" Voltage charts that proclaim states of charge are amusing, especially when it is not pointed out that these are rested voltages, not voltages under load.

Now if the voltage/SOC chart was given out by the battery manufacturer for their specific battery, I would put more stock in them, but I would not put any stock in them unless the battery had not seen any charging or discharging source for many hours, unless I had been monitoring them for many many cycles while discharging them in a similar manner.

If someone sees 12.02 volts under a 5 amp load and freaks out cause such and such a chart says it is in the danger zone, well I guess the only damage done is on the person who freaks out and starts recharging prematurely, and this can only be a good thing for the battery, so no harm done.
Unless you fire up your generator next to me.

Mark, my old grp 24's and my present 6V's fully charged were/are 12.8V.

Chemical reactions at low temperature get groggy.

Lesee, stick your finger in 35 degree battery electrolyte and watta ya got?

Do it in 160 degree electrolyte and watta ya don't got?

Of course thing is sarcastic humor, but it is oh so factual. Take that 35 battery and place it in outflow of a heater and let the temp rise to 80F. Now what does your volt meter say?

mena661 wrote:
Fully charged 12V should be 12.8 not 12.6.

This specification is for "AGM". Deep Cycle acid/lead is 12.67 volts (12.6 to 12.7 on many meters).

The quick answer is NO HARM...

It does seem however to drop down rather fast for that short of time.

My two 12VDC GP24 Interstate vatteries have been sitting outside in the battery box totally dosconnected since late October last year and I just checked them a couple weeks back and they read 12.6VDC. They were on the converter/charger about two months back for three or four days.

consider this chart showing DC Voltage verses state of charge of deep cycle batteries...



You should not ever let a deep cycle battery discharge below the 0% SOC or 10.5VDC or it may do damage to the battery.

Most of us like to not let the deep cycle batteries drop below 50% SOC or 12.0VDC.

Roy Ken