Good morning everyone,
Whenever I take my foot off the gas to coast, come to a stop etc. My amp gauge shows that I'm no longer charging. As soon as I get the rev's up, it goes right back to charging. When this happens I get the usual dimming of the lights and if I'm using them, the wipers slow down. My battery always has a good charge and there is never any trouble starting the truck. My question are: Is this normal? Does the alternator have to reach a certain RPM for it to put out enough juice to operate everything? Does this sound like a bad voltage regulator?
I appreciate any help, and thanks in advance.
Don W.
Burnaby BC:

'72 Camper Special 390/C6

 

Sounds like it could be either or.
my advice would be to take your truck to an auto parts store, auto electric shop, ect & have them test your charging system, and IF they find your altrinator bad definatly replace it, but also change your voltage regulator, as it is just good insurance for what they cost.

 

I would check the connections to the voltage regulator. I just had this problem, and when I replaced it I noticed all the connections to the old one were rusted, and it did not have a real great ground to the fire wall either. Good Luck.

Brendan
1977 F-250
351M / 4-Speed
33" BFG Tires
www.angelfire.com/ma4/1977fordf250

 

I believe I remember that some of the older voltage regulators are adjustable. I think some have a minimum RPM like you said. Look at the condition of your belt for signs of glazing and the pulley to see if it is shiny where the belt may be slipping slighty.

 

I dont know, if this is your situation, but when I or (we) start adding more accessroies, like aux lights, stereos, amps, things like that, the system can actually discharge at idle. You can maybe upgrade the one you have, to put out more amps at idle, which would really help out the battery, since those alt only put out about 60amps. Even a low batterey could pull that amount. If you think you may go this route, have your alternator rebuilt by a proffesional, he can install a beefy armature, and stator assembly, and give you a heavy duty regulator. Another thought is you can put on a smaller drive pulley on the unit. Good luck in your decision

 

Is this an aftermarket amp guage that you or somebody before has installed? If so, it may have been installed with undersized wiring, causing a voltage drop to the whole elec system. Make sure it has at least 10 guage wire to the amp guage if this is the case, or eliminate the guage entirely (tempoarily) to see if the problem goes away.

 

[font color=red size=2]My '73 has always acted like that too. At idle the lights are a little dimmer, wipers go a little slower and the heater fan blowes a little slower. But as soon as it is off idle, everything is fine. It has been that way since I got it (about 6 years). And I have replaced the alt, regulator, battery and cables. I figured that is just the way it is. I've never had any trouble with a weak battery, or it not charging enough - so I just don't worry about it... but that's just me.

Marty