voltage regulator
"SaladinoJA" wrote in message
...
My four year old batteries were not coming up to charge, I would see the
voltmeter reading 13 volts. I tested the alt. at idle, and at about
1500rpms. I
took out the batteries and had them loaded, the verdict was to replace
them
(which I did). The problem is at idle everything seems to be great, but at
higher rpms the batteries discharge, I see a steady discharge on both the
voltmeter and the digital display on my sonar. How do I determine if its
the
alt. or the regulator. The motor is a 1999 4.3 ltr mercruser and has the
55amp
mando alt. Thanks for listening.
John
Newer Car alternator systems charge higher when cold than when hot.
Batterys require more voltage to charge cold than when hot. You can
overcharge and boil a battery if you charge at too high a voltage. PLUS
it's assumed that when cold the battery has just beeen massively discharged
(you just started the engine) and needs to be recharged quickly. If the
battery is discharged then charging at a higher rate won't hurt it.
My ALT system in my boat and car charge at 14.3V when cold and drops to 13.6
when hot. That may look like a discharge to you. Only way to tell is with
a GOOD voltmeter that's been checked (accurate).
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