Just replaced the battery on my '97 Chevy Cavalier. The voltage measured with the engine running is about 14.7 volts. Is that too high? Is there any way to adjust it? The voltage stays pretty constant whether idling or revving the engine. Previous battery lasted about 4 years.
Thanks,
Art Harris
That's damn near on spec. I'd prefer to see 14.1 to 14.3 myself but GM seems to be setting their voltage regulators higher these days.
nate
14.7 is pretty good. Leave well enough alone. 4 years for a battery is pretty good, too. Mine only last 3 years. Texas heat eats them in no time.
The factory service manual for at least some 1990s Honda alternators specifies 13.9 to 15.1 volts with no loads applied. If you turn on the cabin blower, headlights, and defogger, voltage should drop to around 13.5 volts. If the voltage goes over about 16 volts, the regulator needs replacement, according to the service manual. The voltage should stay pretty constant when revving.
I now replace my car batteries pre-emptively, since I understand using them until complete death reduces the alternator's life. (Of course, letting the battery die regularly and using the car alternator to recharge it will also reduce both battery and alternator lives.)
Four or so years has been about the average for the three car batteries my 91 Civic has consumed, but I was not careful in the early years, letting the battery go dead several times.
wrote
The best charging voltage for a battery varies with tempature. 14.7 is right if it is cold. What was the ambient temperature? How accurate is your meter? What voltage do you read when the engine is off?
Mark
Heed Mark's advice. Temperature is a MAJOR factor. All charging system voltage regulators are temperature compensated -- the colder the temp, the higher the charging voltage. There is no adjustment on any modern charging system that I am aware of. FWIW there is typically about .1 to .3 volts drop between the alternator output terminal and the battery + terminal depending on loads. Where did you measure?
Don
No *STOCK* charging system, that is. Transpo makes some nice aftermarket voltage regulators, some of which are adjustable for voltage. I'm running one on my Porsche right now because I don't like the way Bosch alternators seem to "charge" at a fairly low voltage -
13.7V or thereabouts. Mine charges at 14.1 at room temp now. Makes a noticable difference in the brightness of the headlights. (of course, so do the Cibie H4's... next up, the girlie's Corrado. Got a set of factory Euro lights and a relay harness laying on the garage floor as I type this.)nate
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