Battery ran down once but looks OK now

[nydude]

I've got an '03 XC70 2.5 turbo.

I had an odd event this afternoon. I parked the car in about 90°F heat after driving it about 5 miles on the highway. Came back about 1hr later and it tried to start by 'pulling' the engine with much effort once. Every other attempt to start resulted in the starter 'clicking' and the dashboard power flickering. Apparently the battery had gone dead, and a jump start put us back in business.

I've never had a battery issue with the car in the year that I've owned it. I exposed the battery when I got home (after 2 more successful starts) and it is about 12.6VDC and the electrolyte levels look good. I know the lights were not switched on.

What could be going on? Is there something else I should be checking on? The only thing I could possibly imagine is if the A/C fans that run to keep down humidity somehow were causing too much drain or were somehow failing. But that's just a stab in the dark.

Any insight would be appreciated!

[billr99]

I've got an '03 XC70 2.5 turbo.

I had an odd event this afternoon. I parked the car in about 90°F heat after driving it about 5 miles on the highway. Came back about 1hr later and it tried to start by 'pulling' the engine with much effort once. Every other attempt to start resulted in the starter 'clicking' and the dashboard power flickering. Apparently the battery had gone dead, and a jump start put us back in business.

I've never had a battery issue with the car in the year that I've owned it. I exposed the battery when I got home (after 2 more successful starts) and it is about 12.6VDC and the electrolyte levels look good. I know the lights were not switched on.

What could be going on? Is there something else I should be checking on? The only thing I could possibly imagine is if the A/C fans that run to keep down humidity somehow were causing too much drain or were somehow failing. But that's just a stab in the dark.

Any insight would be appreciated!

Two things. First, high heat can be just as damaging to a battery as cold. Its possible that you've dropped a cell and are now not producing full current despite the voltage you read. Second, if the battery is the original it might just be time after 7 years for a new one.

Cheers,

Bill

[sjonnie]

What could be going on? Is there something else I should be checking on?

Sounds like your battery. Charge your battery overnight, check the voltage in each cell, they should all be identical, about 2.1-2.2 I believe. If you have a short in one cell it will show up considerably less, about 1.6 or something. Specific gravity is also a great check if you have a hydrometer. If the battery checks out reinstall in the car and start her up. Check the voltage over the battery or jump terminals, should be about 14V, if not your alternator is shot.

[nydude]

Sounds like your battery. Charge your battery overnight, check the voltage in each cell, they should all be identical, about 2.1-2.2 I believe. If you have a short in one cell it will show up considerably less, about 1.6 or something. Specific gravity is also a great check if you have a hydrometer. If the battery checks out reinstall in the car and start her up. Check the voltage over the battery or jump terminals, should be about 14V, if not your alternator is shot.

I'll buy/borrow a hydrometer. In the meantime, how do you check the voltage of the individual cells? I only see the main terminals on the original Volvo battery.

Thanks for the advice!

[sjonnie]

It's actually pretty easy. You need two lengths of scrap wire attached to the end of your voltmeter. Open up all the cells on the battery. For the first cell put the negative on the negative battery terminal, then put the positive into the electrolyte of the adjacent cell. For the next cell, put the negative electrode into the first cell, and the positive into the one next to it. For the last cell, attach the positive to the battery terminal and put the negative into the electrolyte.

[nydude]

It's actually pretty easy. You need two lengths of scrap wire attached to the end of your voltmeter. Open up all the cells on the battery. For the first cell put the negative on the negative battery terminal, then put the positive into the electrolyte of the adjacent cell. For the next cell, put the negative electrode into the first cell, and the positive into the one next to it. For the last cell, attach the positive to the battery terminal and put the negative into the electrolyte.

Awesome. I've never heard of that!

Thanks again.