Dreadknot

Just installed a brand new cs144 from a 96 roadmaster as per instructions from another thread. I purchased the alternator from summit and wired it in yesterday. Only charges to 12 volts. Took it back and got another one with more amps just to see what happens. Same thing. Its a 77 with generator light. I have tried both si to cs harness with and without resistor. I no longer have an original alternator gauge. My gauges are updated to digital. But if I put the old 140 amp alternator in, it charges to 14 but does not keep up with my cooling fans at idle, hence the switch. im now lost at what is going on.

ezobens

Charging to 12 volts in itself really isn't an issue-
It's if it can keep the battery charged at 12 volts under load.
What happens when you turn all the accessories on (headlights, blower motor etc)?
Does the voltage remain at 12 volts or do things start to dim and slow down?
Have you tested with a good voltmeter or are you relying on the gauge in the dash?

ajrothm

It doesn't seem like the CS144 is self exciting. Did you try revving the engine to about 2500 rpms to see if the volts come up?

Seems like the alternator is not getting the 12v start up signal it needs, either you have the wrong plug adapter or something.

carriljc

Go perform the tests in posts #9 of this thread:
https://www.corvetteforum.com/forums...post1595487859

You should be easily reading something like 13.3 to 14.2 vdc. Mine does and I got it at a junkyard just to check if it fit.

You can also get the alternator tested at your local parts store to see if it's ok.

But, really, you oughta do both. Do the checks in the above mentioned posts to make sure AND also go get the alternator checked at your local parts store (they should do it for free).