When do you upgrade the Altenator???

[TSully980]

I don't know if I had a bad battery or if I need to upgrade the altenator.
The 99 cherokee with the 4.0 motor would not start or idle for couple of weeks. I eventually replaced the battery. The old battery wasn't even a year old. When the battery was replaced everything worked as it should.
I had installed a 550 watt amp for the stereo. I am wondering if I need a larger altenator to keep the battery charged. I do know that the stock altenator is a 117 amp. Seems like that should be able to keep the battery charged... but I don't know for sure. Thanks for the replys...
Troy

[badron]

Have you had you charging system checked for proper output?

Have you check for a large battery drain with key off. I not sure how on the Cherokee this is done. Maybe someone will jump in and help there.
.
Do you use the big stereo amp(s) with the key off a lot? Real hard on the battery.

Do you set at idle and crank the tunes a lot. With big stereo amp(s) this is a real no no. Even if you upgrade it may not help. Many ALT. put out about the same amps at idle. It's at about 1800 RPM that the big boys start to show there stuff.
I do hear that the 160 amper does show some real improvement at lower RPM. But I have never played with one my self. So take that for what it worth. Luck

When to up grade? After having her checked out.
1: Watch your volt meter if it dipps alot below 14 volts. up grade.
2: If you have to replace you battery a lot.

R Robinson