rickjaffe

I've been having an on going charging problem.

when I load up with a/c and lights there is a discharge. I put in a new battery and alternator a year ago and that didn't solve the problem.
I've just put in another alernator and It's still 12.5 with both a/c and lights on.
they've checked to see if there is resistence in the wire between the alternator and starter and back to the battery. alittle but when they put in another circuit it didn't solve the problem.

the ground to the battery looks ok, but they will check the current on that as well.
any ideas of what else to look for?

thanks,

rick jaffe

the flyin' scotsman

Where are you measuring the 12.5v ? You should be approx. 14v engine running above idle rpm.

rickjaffe

12.5 is at idle. above idle it charges.
isn't it supposed to charge with load at idle or is that too much to ask for a 21 year old car?

the flyin' scotsman

Measure the voltage with the car not running, car running at idle and car running above idle with a ll loads off.

Then load the system, engine running above idle, until you see the big drop then we can go from there.

928 at last

You're not relying on your dash gauge for these readings....
You want to be under the hood and on top of the battery with a (Preferably Digital) multimeter to take the readings.
My gauge reads consistently a full volt low on the dash. On the meter, all is well.
Other than that, +1 on what Malcolm said.
There's lots of help on here as to how to check & diagnose the charging.

Stephencs601

Use a voltmeter and check the charge at the battery. Then check the charge at the Jump post. See what you have, should be 13.5 or better. I have the same problem and so far I found dirty grounds and a dirty relay. Cleaned all grounds and replacing relay. So far Gauge shows 12.5, but I know gauge is not accurate. Try Wally, he is the master of all electrical.
This is my opinion and reflects my experiences only.

Alan

Tighten the alternator belt - it needs to be really-really tight - if an alternator belt slips at all it will slip at idle - especially under high load - and even then it will probably be fine under other conditions.

Otherwise get a smaller alternator pulley and/or a larger crank pulley

Ribbed pulleys and belts are better than V belts - more surface areas for friction to transfer the load without slipping.

Alan

rickjaffe

if the alternator belt is slipping wouldn't there be a squeeling sound. I think so because I'm having the squeeling problem with another car.

WallyP

No, the ribbed belt doesn't usually squeal. If it has been slipping for some time, it may be hardened and worn, and won't drive the alternator at idle.

You won't believe how tight the belt should be. Using the Porsche belt tension gauge, the timing belt is set to 5.0 - the alternator belt is set to 8.5-9.0!