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Heres what I have a problem with. 1 year ago I bought an Optima battery. It now is a bad battery. I put a regular battery in it (750 cca). I also have a new alternator installed. At idle, it is charging at 16 volts. This isn't normal?? Could I have a faulty voltage regulator? I noticed this before I put on the new alt, and with the new alt it is still doing it. Prehaps this caused my Optima to fail. Possibly being over charged. Any ideas? I hope it is as simple as the regulator.
Definately the regulator!!!!! Just happened to my '79 150. All the same symtoms - only mine was gettin pushed to nearly 18v and it popped a couple of bulbs in the truck. The battery would hiss after the truck was shut off.
Thanks for the info. I replaced the voltage regulator and here is what happend. My battery now is being charged at 14 volts and idle. (used to be 16 volts) As I rev the motor, it does't increase in voltage. I dont get it. What is the normal charge on a stock alternator? It has a 390 in it. What am I over looking? Any ideas?
Shouldn't my voltage increase as I rev it? It stays between 14 volts to 14.10 volts. I always thought the more you reved the motor the more the alternator puts out.
The higher the engine RPM's, the more Current (amps) the alternator
is able to produce. Voltage should stay close to 14 volts regardless
of the RPM's if the regulator is doing its job. Anything over
14.4 volts for an extended period of time is too much voltage
output for an alternator. I prefer to use a good quality
digital meter to measure this.