S90 Battery not charging...

rpicou923 · Post by **rpicou923** » 10 Jul 2013, 16:29

Sooo, my battery is not charging and I cannot figure out why. I took the battery down to Autozone and had them test it and it tested fine. I put a full charge on it, cleaned the connectors and cables and reinstalled. I took the Alternator out and took it down to Autozone and they tested it and it tested just fine, passed with flying colors. So I reinstalled it, cleaned the hell out all the connections and everything tested the system out. Nothing. I did a voltage drop test on the cables and they were fine. Measured the Voltage at the battery and at the alternator (with the car running and not) and I get 12.30 Volts. I even stuck my camp meter on the cable going to the battery and I get 0 Amps. Any ideas? Is there a fuse somewhere that I missed that supplies field voltage to the Alternator? Any help is much appreciated.

1998 Volvo S90
160,000 miles.

danr960 · Post by **danr960** » 13 Jul 2013, 17:06

Does your alternator light go on when the ignition is turned on but engine not running?

I believe, though I may be wrong, that bulb is part of the charging system.

DanR '94 964 386,000 miles (152,000 on the new engine)

Post by **jimmy57** » 13 Jul 2013, 17:56

Right, the bulb circuit is the initial rotor magnetizing supply to make it charge at low revolutions.
If the skinny wire to back of alternator is broken or there is an issue with instrument cluster, then it will not charge until you rev engine over 3000 rpm.

rpicou923 · Post by **rpicou923** » 15 Jul 2013, 10:58

Well I am stumped! LOL. I found the Volvo Electrical Drawings and started tracing the system out with my Mulitmeter. I was not getting any field voltage to the Alternator so I started going backwards from there and everything checked out. I disconnected everything and started checking the wiring to see if I had a ground somewhere and did not find anything. Reconnected everything and voila! my Alternator is working again. I am getting 14 volts while the car is running and I loaded the Alternator up and stuck my clamp meter on it and it was putting out about 80 Amps fully loaded. (it puts out about 30 Amps sitting at idle.) My battery charger has a Alternator check and it passes while the car is at idle, but if I load it up and do the test it says fail. Only thing I can think of is a bad ground. If the alternator is putting out 30-80 Amps @ 14 volts, it should be fine, right?

danr960 · Post by **danr960** » 15 Jul 2013, 14:11

You did all of this after confirming that the alternator light on the dash illuminates when the ignition is on engine not running?

Maybe your regulator is the problem, try removing it and inspect.

DanR

Post by **jimmy57** » 15 Jul 2013, 14:39

The ground is the alternator being bolted to its brackets via the multiple bolts used.