[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.
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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