Can my depleted battery be charged again?

September 1, 2016 | By Staff


I have a 1957 Ford Ranchero that is my baby, so much so that I rarely drive it, and that has become a problem. A couple of times over the years I have even had to drain the gas tank and clean out the fuel system. But my biggest problem is that each spring it seems I have to buy a new battery. My garage does not have electricity going to it, so I can’t hook up a trickle charger.

I bought an Optima battery last year because I was told they would last up to 10 years, but mine won’t even turn the engine over after just a few months. Also, I have been told that once an Optima is deeply discharged it cannot be recharged and will have to be replaced. Is this true? Tell me it isn’t so.


It isn’t so…really. You can recharge an Optima that is flat most of the time, but it is a little more complicated than recharging a flooded (wet cell) battery, and you need to keep an eye on things.

This method is for the do-it yourselfer using the equipment most of us have on hand. The plan is to trick your traditional charger into charging that deeply discharged Optima.

Things you’ll need:

Battery charger (under 15 amps)

• Jumper cables

• A good battery, preferably above

12.2 volts. (It can be an absorbent glass mat [AGM] or conventional battery.)

• The deeply discharged Optima

• A voltage meter

• A watch or timer

Hook up the good battery and the deeply discharged Optima in parallel—that is: positive-to-positive and negative-to-negative. Next, hook up the good battery to the charger. Turn on the charger. The charger will recognize the voltage of the good battery and start providing a charge.

Leave the batteries hooked up for an hour, and then check to see if the Optima is slightly warm or becomes hot to the touch. Batteries become warm during charging, but excessive heat may indicate a fault with the Optima. Discontinue charging immediately if the battery is hot. Also discontinue the process if you hear the battery off-gassing, which usually makes a hissing sound. If it’s either hot or gassing, stop charging immediately; the Optima is defective.

Use your voltage meter from time to time to see if the Optima has charged to 10.5 volts or higher. This generally takes less than two hours with a 10-amp charger. If it has reached the desired level, disconnect the charger from the wall outlet and remove the good battery from the charger. Now connect only the Optima to the charger. Turn on the charger and continue until the Optima is fully charged or until the automatic charger completes the charge process. The Optima should be restored and ready for service.