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Alternator question

Hi all,

Let me begin with this info - 1990 740 wagon 130K on B234f engine. Battery checked by Les Schwab's and found to be OK.

Last week I had to get a jump to get it going, the first time since I replaced the battery about 3 years ago. I put a charger on it all night and, so far, no more problem.

Question - I have a small digital volt meter that plugs into the lighter outlet. When I start up in the morning it reads around 11.7V, as I see it that's a net loss for the battery; once the engine etc are all warmed up it reads around 12.9 to 13.5V, a net gain for the battery.

My feeling is that the alt. is on it's way out the door.

Any ideas?

Thanks much,

Perk (:>)

Reply to
Perk
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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:

12.65V0% 12.45Vu% 12.24VP% 12.06V%% 11.89V or less=Discharged

**Some more reading:

Reply to
clay

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

Reply to
Perk

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.

Reply to
James Sweet

Thanks James, I'll check that too.

P. (:>)

Reply to
Perk

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