Low voltage question

[Swift101]

Hey Everyone,

This week I noticed my alarm went off on it's own a few times. I just checked the battery voltage and it's 12.2 after sitting for 14 hours. When I start the car it goes up to 14.7 so I guess the alternator is charging the battery just fine. I supposed I need a new battery?

Any suggestions?

-Thanks

 

[Superflop]

You could take it in and have it tested. It could just need a good charge thrown at it.

 

[JR]

SuperFlop, you can use a cheapo multimeter and a friend to load test at home.
Test battery voltage at terminal post not at cables or downstream. Have your friend crank the engine, if you drop two volts you have a bad cell. If the drop is minimal you could be OK. Also it could be a small short/draw internally, that means it dies over time.


Harvey

 

[Wolf359]

Cause and effect aren't necessarily related. Your alarm could be going off due to a bad sensor and 12.2 volts isn't that bad a voltage depending on how old the car battery is. Mine goes as low as 11.5 volts, but that's in the winter when the temperature is 20 degrees. Regular weather anywhere from 11.9-12.2, but mine is 8 years old. You could search for a state of charge chart, it's usually 12.5-12.7 volts fully charged with no load when it's been at rest for a few hours at 70 degrees. Anything else and you get a lower voltage. Go to an auto parts store and have them load test the battery. That's the only way to be sure.

 

[BigD1]

Your battery is discharging pretty fast for only sitting 14 hours. For example, my Volvo which is not being driven much right now, after three days the voltage is 12.5 volts.

If you can, pick up one of the battery maintainers, and see if it can help de-sulfate the battery. I have been putting my battery on a Schumacher battery maintainer to keep it fully charged.

 

[eljefino]

Maybe it's the alarm! Aftermarket electric stuff isn't up to the same snuff as OE.

Throw a 2 amp charger on it while it sits.

 

[69GTX]

I consider 12.2-12.3 volts at nominal winter temps (20-30 deg F) to be the warning range. My last battery would drop from 12.65 volts to 12.2 over 24 hours (6 years old). I'd also check your cell fluid levels if accessible. That could be causing your problem. And if so, refill and charge the heck out of it to restore it to life. I got 3 extra years on that last battery by doing that along with frequent mini-charges/float tender. Not being able to hold a charge is a problem...unless you have some parasitic draws.