Alternator question

Don't know about checking the voltage at the lighter or the accuracy of a tester that plugs into a lighter. If you check it at the battery with the motor running you should see 14.4V.

Either something is draining the battery or the battery is toast.

A fully charged** battery should read 12.65V. Voltage and charge states:

**Some more reading:

Thanks Clay, I'll check it, prob. tomorrow, and get back to you.

Don't forget that it takes a lot of juice to start the engine, the battery could be a bit weak but still acceptable and drop down a bit after starting until the alternator replenishes it.

I would be curious to see if it drops further after sitting for a few days though, it's easy enough to measure the drain with the car off, glove box lights in a lot of cars are notorious for sticking on and causing battery drains.

Thanks James, I'll check that too.

P. (:>)

How was it tested, with a load tester? At the battery it should go to around 14+v for awhile and back off to around 13.6- 13.8. Cables need to be checked and they can eventualy break inside the insulation, the ground may be bad. Why didnt the guy check alternator output when he checked the battery. At that age cables need looking into also as it wont charge with bad cables.