Just because the OCV, no matter how battery has sat, is reading "between 6 and 7 volts", that shouldn't be the sole reason for condemning a 12 volt lead acid battery as unusable, junk or scrap.
The O.C.V. (Open Circuit Voltage) only indicates the percentage state of charge.
Be careful when the OCV is below 9 volts, you may damage some chargers by trying to recharge a battery that reads 9 volts OCV and below.
A OCV voltage reading below 10.75 volts indicates the battery is Zero (0%) percent state of charge
CAUTION WARNING: A battery expels MORE Hydrogen gas from a discharged battery than one that is charged.
A trickle charge (especially on a constant current charger) may be worth a try. If the ammeter isn't bouncing around and no smoke is evident, try to continue charging. Don't be surprised that it may require 16 to 24 hours of charging on a 10 to
15 ampere charger.
Hopefully, after 16 to 24 hours and once battery is removed from charger, the battery has attained
100% state of charge.
If you want to terminate the charge for any reason: 1) Unplug or turn off the charger and 2) Disconnect the charger leads from the battery. 3) After removing the battery from charge, leave battery sit and "cool down" for at least 72 hours. The OCV is unstabilized due to a surface charge once the battery attains full charge. 4) Wait for 72 hours for surface charge to bleed off. The surface charge won't become stabilized until at least after 72 hours.
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