Battery Bad?
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Senior User
Joined: Mar 2003
Posts: 318
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From: Wisconsin
Battery Bad?
Lately I have been noticing that when I am at stop lights, with the headlights on, the battery gauge drops to about the N on normal and my headlights dim and the heater fan (if its running) slows down. Then, when I am on long trips, the battery gauge goes way up to just under the 18 max, even with the headlights on. Also, the battery is almost 6 years old. I was wondering, is it the battery, or is it the alternator starting to go bad by not regulating how many volts go to the battery?
Posting Guru
Joined: Oct 2004
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From: Annapolis,MD.
Can't say for sure,sorry, But if it makes you feel any better,mine has been doing the same thing for about 4 yrs. and 40,000 mi.on 2 different batteries.But when the gauge pegs I have checked a couple times and is only up to 14.8 even though idiot gauge shows 18.
Elder User
Joined: Apr 2002
Posts: 813
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From: NJ
my guess is yes the battery is bad. it is six years old and needs replacing anyway just because its not worth getting stuck with for 65.00$. now the alt gauge spikeing may also be what caused the battery to be bad. if it is overcharging this will kill the battery and if it is undercharging the battery will do this toi the gage because the battery is low and the regulator will try to charge it up.
Post Fiend
Joined: Jun 2001
Posts: 5,228
Likes: 5
From: Running Springs CA
The regulator is not regulating. Check all of the connections, especially the grounds. The battery may be killed by a bad alternator/regulator, but as long as it starts the truck every time, the battery is ok.
Jim
Jim
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
I agree with jimandmandy on the voltage regulator. Something else to consider is actual battery terminal and cable connections. I recently dealt with a problem that gave me the correct voltage everwhere i was supposed to have it. However, the positive battery cable wasn't allowing enough AMPERAGE to the starter. Three starters later, I removed the entire wiring harness between the battery and the starter and took an OHM meter to it. 85.5 ohms worth of resistance down a piece of 6 gauge wire thats less than three feet long is a serious problem. I replaced it with a new cable (ohmmeter reading .04 ohms resistance) and lo and behold, started right up. The reason I had such a hard time finding the problem... the cable had corroded from the inside out. Cutting the jacket off the old cable revealed a run of nothing but copper oxide powder and a few tiny strands of wire inside. So check the connections and beware of hidden culprits.
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Senior User
Joined: Mar 2003
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From: Wisconsin
Is there any way to check if the regulator is working right? I know the battery is getting old and I will be replacing it soon, but I want to make sure the new one doesn't get wrecked because of over charging. Or, by replacing the battery could I tell if the regulator is bad if it doesn't over/under charge anymore, or would this way just be covering up the problem (if it's the voltage regulator causing the problem) because the battery is new?
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
Used to be that if a regulator was going bad you would usually wake up to a dead battery because the points in the regulator would not flip over and keep the battery from draining. Unfortunately, with regulators that rely on solid state technology, its just not that simple. In short I don't know of a way to test for a bad regulator. But don't rely on my limited knowledge. Someone else may know.
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Post Fiend
Joined: Jun 2001
Posts: 5,228
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From: Running Springs CA
Get a digital multimeter and measure resistance at all connections. Measure the votage at the battery terminals with the engine running at various speeds. It should measure between 13 and 15 volts.
Jim
Jim
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