Freaky Battery Problem

[snomaker321]

I went to the gas station yesterday and was stopped for about 2 minutes while I put $10 in my tank. When I got back in my truck it wouldn't start-dead battery. I tried cleaning and wiggling the connections and even replaced one but got nothing. We tried jumping it with my girlfriends jeep but even after 20+ minutes connected, I didn't have enough to turn it over more than once or twice and it didn't seem to be getting any better. Eventually we decided to take the battery out of my girlfriends jeep and put it in my truck. We did and it started right up and got my truck home. Put the battery back in her jeep, checked to make sure it still started, and we went to bed.

This morning she left in her jeep to go to class and stopped at the same gas station to get a coffee. I get a call from her 10 minutes later, dead battery.

Whats going on here? Is something wrong with my truck causing my battery to die and damaging hers when we put in in my truck? Is something at the gas station killing batteries? Or is this just a freaky coincidence?

Her battery is almost 4 years old. I think mine might be the original one in my truck, which would put it at 9-10 years old

 

[RonD]

Car batteries last about 5 years with normal use, yours is probably it's second battery.

The plates inside wet cell batteries lose chemicals through discharge and recharge so over time so they simply can not hold a charge any more.
Usually 1 cell(there are 6) will develop a short which will drain the other 5 over a few hours.
Or a short that will not allow the battery to hold a charge at all.

Test batteries with a volt meter.
12.8volts is a new battery
12.5volts is a battery at 75%
12.2volts is a battery at 50% <<this is pretty much a dead battery

If battery is not connected to anything and you put a volt meter on it and the voltage is dropping as you watch the meter then you have a shorted cell
Each cell provides 2.1volts, so 6 x 2.1 = 12.6v

Different vehicles require different amp levels to start, so a battery at 50% might start some engines but not others, on a warm day.

Jumping can effect the "good" battery, if it was older, so yes it could be that the strain of jumping took a year off the life of the jeep battery.

It could also be that your voltage regulator or alternator is putting out too high a voltage, above 15volts, this would cause more loss of chemicals from the plates speeding up the demise of your battery and then hers from the short trip.

Although in her case I would suspect lose cables on the battery, since battery was just removed and replaced and did start after sitting overnight, so loose cable fits better in that scenario.