My son borrowed a car and the battery seemed fine, car started fine every time. However it died after my son left some overhead lights on in the car overnight. We jumped it, and he drove about 20 miles, but it didn't seem to take any charge, so it had to be jumped again.

It has enough juice to turn on lights and the dash, make the noises when the key is in the ignition, but we just get the clicks rather than the engine trying to turn over.

Hooked it up to a charger for a few hours, same thing.

So my question is does draining a battery completely result in it not wanting to take a charge anymore? Or is this a condition that mostly affects batteries that were on their last legs to start with? Can a battery in this state be revived?


So I removed the battery and cleaned the contacts but hooked up the battery to a new NOCO G3500 smart charger. From the start, I noticed some gas being released from at least one side of the battery (it has two caps, each one covers 3 cells). I removed the caps, and could see that each of the cells was bubbling as it charged, except for one. That one was on one side of the battery. So 5/6 cells seem to be taking a charge. After 24 hours on the charger, the NOCO was still showing 75% (flashing). I removed the charger and it registered ~11.25 volts. The next day, it was showing ~10.5.

  • yes, allowing a battery to fully drain will likely damage the overall health and shorten the remaining life of the battery. this is especially true if left depleted for long periods of time. like mikes said, older batteries may not recover after being drained. have a shop or parts store test the battery. i would also make sure the alternator is charging properly
    – user4546
    Aug 15, 2015 at 21:17

4 Answers 4


One other thing that happens when a multi-cell battery is completely discharged is that one of those cells may be driven into reverse polarity. This will have a drastic effect on a battery's life. Most will tolerate this only a few times, some types only once.

This from Wikipedia:

Damage from cell reversal

Subjecting a discharged cell to a current in the direction which tends to discharge it further to the point the positive and negative terminals switch polarity causes a condition called cell reversal. Generally, pushing current through a discharged cell in this way causes undesirable and irreversible chemical reactions to occur, resulting in permanent damage to the cell. Cell reversal can occur under a number of circumstances, the two most common being: When a battery or cell is connected to a charging circuit the wrong way around. When a battery made of several cells connected in series is deeply discharged.

In the latter case, the problem occurs due to the different cells in a battery having slightly different capacities. When one cell reaches discharge level ahead of the rest, the remaining cells will force the current through the discharged cell.

This is probably what happened to your battery and why it happened so suddenly.


There are a few scenarios that can cause battery charging issues. First check the connections. If it is serviceable check the water level. If it is low, charging may have overheated and damaged the plates. If the battery was a newer technology AGM type (advanced glass mat technology) and it was charged with a older style conventional charger the battery may have been damaged. AGM batteries require a "smart charger". Another potential issue is older chargers often will not charge a completely dead battery. It needs to see some voltage to initiate the charge cycle. The method varies with the charger. My old Sears Craftsman requires me to jump the dead battery for 5-10 minutes prior to putting it on the charger. Another scenario is as you alluded to, that the battery may have been on its' last legs and running to dead pushed it over the edge. If this is the case the only solution is replacement.


What I would do is first is put battery on charge over night if battery was drained to much then alternate won't 0rod7ce quite enough to charge it.


I would say that 2 hours on charge will not charge the battery sufficiently. Leave it on for 24 hours at least. A 100AH battery will take 10 hours at 10 amps, 20 hours at 5 amps, and my smart charger goes at only 2 amps (initially at least) when the battery is flat, so 50 hours if at 2 amps!

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