My voltmeter has started acting differently since installing a new alternator. I put in a 75 amp instead of the stock one. The car does have underdrive pulleys. I never had this problem prior to installing the alternator. The alternator did charge the battery. I took it on the highway twice for about 20 minutes each way, and it started this morning when I came out. It seems that at idle the voltage reads 12, and comes up to 14 immediately upon acceleration. Also, turning on the heater, flashers, lights, etc. make it go down where before it wasn't even noticeable (with the exception of the heater). After reading a bit, I know the first place to start will be to get a meter on it, and second to pull it and have it tested to see if it's defective, but does anyone have any idea what could be causing this? Could the alternator going have taken out the voltage regulator? Thanks
Voltage Meter Fluctuates after new alt install
- Thread starter 87GTVertDude
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TenorPlayinGuy
Founding Member
voltage regulator is internal on the alternator. Do the lights dim with the gauge? Mine has done this regardless of what alternator I've used. It may be a phase issue with the diodes, take it in and get it tested. It may actually damage your battery cells if the phases are now overlapping consistently.
Why did you change the alternator? If the old one went bad it may have taken your battery with it.
I'm pretty sure the stock one is a 75A unit, is it not? Keep in mind...not all stock replacement alternators are created equal. A lot of refurbish places (Pepboys, NAPA, etc) use cheaper, lower quality components in their units that can not only perform erratically, but shorten their lifespan as well as your batteries life span.
I can't for the life of me understand why you went with a standard 2G alt when your stock one bit it. The cost to upgrade to a 3G 95A-130A is negligible in comparison. I just received today my fully polished, completely refurbished upgrade 150A 3G unit. It cost me all of $135. The only thing I really need to upgrade with this alternator is the power and ground wires.
I might just go put it on this afternoon as a matter of fact.
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1987stangman
Member
- Jul 12, 2006
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I'm pretty sure the stock one is a 75A unit, is it not? Keep in mind...not all stock replacement alternators are created equal. A lot of refurbish places (Pepboys, NAPA, etc) use cheaper, lower quality components in their units that can not only perform erratically, but shorten their lifespan as well as your batteries life span.
I can't for the life of me understand why you went with a standard 2G alt when your stock one bit it. The cost to upgrade to a 3G 95A-130A is negligible in comparison. I just received today my fully polished, completely refurbished upgrade 150A 3G unit. It cost me all of $135. The only thing I really need to upgrade with this alternator is the power and ground wires.
I might just go put it on this afternoon as a matter of fact.
View attachment 165939
I think the wiring scares some folks, but your right it's a must have even if the 2G is still good and takes no real skills to install.
The wiring is simple: you just follow the link to the pictures...
Stangnet 3G install sticky http://www.stangnet.com/mustang-forums/646825-3g-alternator-install-how.html#post6673702
The lights are dimming with the gauge. When in park, if I give it gas, the meter raises as does the brightness of the headlights. Pull it and get it tested?
Blown88GT
Founding Member
I'm pretty sure the stock one is a 75A unit, is it not? Keep in mind...not all stock replacement alternators are created equal. A lot of refurbish places (Pepboys, NAPA, etc) use cheaper, lower quality components in their units that can not only perform erratically, but shorten their lifespan as well as your batteries life span.
I can't for the life of me understand why you went with a standard 2G alt when your stock one bit it. The cost to upgrade to a 3G 95A-130A is negligible in comparison. I just received today my fully polished, completely refurbished upgrade 150A 3G unit. It cost me all of $135. The only thing I really need to upgrade with this alternator is the power and ground wires.
I might just go put it on this afternoon as a matter of fact.
View attachment 165922
Hi, thanks for the info about aftermarket retailers. I wasn't aware of this upgrade and I was in a hurry to get the car driving again. So making modifications wasn't on the agenda. The only mod I thought I was making was upping the amps, which apparently you're telling me I didn't even do (good thing I didn't go for the 65) And Stangman is correct, I'm not very confident with my soldering abilities, so I wouldn't consider doing that upgrade on my own. That said, the next time I replace anything I'll do a more thorough inspection of what's available here.
Blown88GT
Founding Member
I'm pretty sure the stock one is a 75A unit, is it not? Keep in mind...not all stock replacement alternators are created equal. A lot of refurbish places (Pepboys, NAPA, etc) use cheaper, lower quality components in their units that can not only perform erratically, but shorten their lifespan as well as your batteries life span.
I can't for the life of me understand why you went with a standard 2G alt when your stock one bit it. The cost to upgrade to a 3G 95A-130A is negligible in comparison. I just received today my fully polished, completely refurbished upgrade 150A 3G unit. It cost me all of $135. The only thing I really need to upgrade with this alternator is the power and ground wires.
I might just go put it on this afternoon as a matter of fact.
View attachment 165918
Where did you purchase it?
