This is for my 2000 Jeep Cherokee 4.0L. I have some electrical accessories on it including some 100 watt off road lights wired to come on with the high beams, as well as heated seats.
I could run all this stuff with my factory 117 amp alternator and didn't have any problems. Well the factory alternator had a bearing that went bad, so I bought an Autozone rebuilt alternator. It worked, but didn't seem to charge well enough at idle. I recently replaced that alternator with a "high output 150 amp" alternator from eBay. It is basically a stock alternator that has been rebuilt to put out 150A. I also upgraded the alternator cable to some larger gauge wire while doing this mod. All connections are clean and tight.
What I have noticed is that the idle charging problem has worsened. If the Jeep is idling with no lights or anything on, the dash gauge reads 14 volts. If I turn on my high beams (and off road lights) while idling the dash gauge will spike to 12 volts, and the headlights and dash lights will dim. If I press the throttle a bit (say up to 1000 RPM) while doing this, everything gets bright again and the volt gauge returns to 14 volts. If my electric fan kicks on while idling at a light, the same thing will happen and the volt gauge will spike to 12 volts until I get moving. It almost seems like the alternator can't handle the load placed on it at idle, but is fine otherwise.
If I'm cruising down the road everything is fine, this only happens at idle. Could I have gotten two bum rebuilds, or is something else the problem?
I could run all this stuff with my factory 117 amp alternator and didn't have any problems. Well the factory alternator had a bearing that went bad, so I bought an Autozone rebuilt alternator. It worked, but didn't seem to charge well enough at idle. I recently replaced that alternator with a "high output 150 amp" alternator from eBay. It is basically a stock alternator that has been rebuilt to put out 150A. I also upgraded the alternator cable to some larger gauge wire while doing this mod. All connections are clean and tight.
What I have noticed is that the idle charging problem has worsened. If the Jeep is idling with no lights or anything on, the dash gauge reads 14 volts. If I turn on my high beams (and off road lights) while idling the dash gauge will spike to 12 volts, and the headlights and dash lights will dim. If I press the throttle a bit (say up to 1000 RPM) while doing this, everything gets bright again and the volt gauge returns to 14 volts. If my electric fan kicks on while idling at a light, the same thing will happen and the volt gauge will spike to 12 volts until I get moving. It almost seems like the alternator can't handle the load placed on it at idle, but is fine otherwise.
If I'm cruising down the road everything is fine, this only happens at idle. Could I have gotten two bum rebuilds, or is something else the problem?