Low battery voltage

[Dave-S]

When I checked the battery voltage on my car with my digital meter, it registered only 11.5 volts. This measurement was taken with the car's engine turned off. When the car is running the reading is right around 13 volts which I assume is normal hen it is being charged by the alternator. But as soon as you turn off the engine, the voltage starts to drop when you look at it with the multi-meter.

Right now I am charging it up with my battery charger. Once it is fully charged, I will continue to keep an eye on it. But I am wondering if there is enough parasitic drain from the electronic components to discharge a battery if the car sits idle for 2-3 days?

[Fox Mulder]

No not in just a few days. It would take a lot longer than that. The battery should be tested to see if it is failing, the charging system can be checked as well to make sure it is functioning properly. 13V with the engine running and no accessories turned on is actually a bit on the low side, I'd expect to see closer to 14V.

[Zebodog]

I wouldn't worry about it unless you're having specific battery related issues.

[Smutty]

Multimeter won't really tell you much unless you have an amp-clamp that you can hook up to see the draw when the engine is off. You need to load test your battery to get a better idea of it's true condition. Somewhat low voltage isn't necessarily a problem unless it's accompanied by a draw or low CCA.

[Dave-S]

So far I have had no starting problems or other electrical issues I can attribute to the battery. Just to be on the safe side, the car is going into the dealer next week to have the battery and charging system checked.

Does anyone know if the voltage regulators for our cars is built into the alternator or is it a separate component?

Dave

[RBD]

Each cell should be 2.1 volts when fully charged. Thus, 6 cells would equal 12.6V. If your reading 11.5V, either you have a battery going out, or it sat for a long time with something drawing it down.

[titaniumskull]

Cold weather has an effect on the battery.
Least you can do is take it to the dealer so they can do a load test. If there is an issue the load test will tell.

[nickpapa]

if there is an autozone or advance autoparts close by, they do free battery and alternator tests. worth a shot if you dont want to waste a day at the dealer

[MikeyTG]

Are you sure your meter is accurate?

[Fox Mulder]

Originally Posted by Dave-S

Does anyone know if the voltage regulators for our cars is built into the alternator or is it a separate component

The alternator is internally regulated. However there is also external control of charging behavior by the PCM through an external sensor at the battery, so if you suspect any issues with the battery or charging system it would probably be best to have it checked at a dealer. Any problems should be covered under warranty, including a bad battery if it's within the full warranty or prorate period.