Originally Posted by robodiaz
I have a 2003, 3.7L liberty and I just changed my alternator over the weekend.
I had a choice of two alternators at Auto Zone, the difference being in amperage. A 136 or 160 amps. The guy couldn't tell which one I previously had so I opted for the larger one because he said it wouldn't make a difference since I'm not running alot of extra electrical devices.
Took it and installed it, test drove it for about 20 min. everything was fine.
Then today I drove to work on the highway and when I got up to around 70mph I noticed a slight loss in power and the engine just wasn't running as smoothly. Drove up a hill and there was a definite loss in power.
Is using the higher amped alternator causing my power loss? I've checked the belt and the connections to the alternator and it looks good.
Should I have autozone test out my car again?
Is the alternator charging?....put a voltmeter over the battery...should read about 13.4 volts at idle.
A larger alternator means it has the ability to supply more amperage if needed; under normal running it will supply the same amount of current as a smaller amperage alternator will.
There should be the main large lead on the rear of the alternator and a smaller plug with two thin leads plugged in.