Get new 160Amp Alt or Overdrive stock one?

[Nitrous SSC]

Problem: When I'm wheeling and coming down trails n' such since I don't have 4-low I'm usualy idling. At night I have all my lights on including my hella's and I'll notice my volts get extremly low. (almost to the red mark)

However when I'm driving normaly or climbing I don't have this problem because the RPMS are up.

On my mustang to help its charging problems I threw on a 3G 130 with an overdrive pulley from ASP. Its worked wonders.

Should I try a pulley swap first? (30$)
or swap it out for a 160 amp on ebay I saw for 134$

Note: funds are extremely tight right now because of the new rims/tires/lift

 

[Blee1099]

I would definately get a higher amp alternator and maybe a optima battery.

 

[410Fortune]

First off have your current alternator tested to determine if its bad.
Second look at the wiring harness.

I just upgraded from the stock 93 4.0L 80amp unit to a 98 Expolorer 130 amp unit, wiring took all of 15 minutes, I am now getting 14.2 volts at the battery at idle, previously I was getting 10-11. The 80 A alternator was 6 months old, it was an Autozone special (lifetime warranty) and it was the 4th one I had gotten from them in 2 years. I learned my lesson and bought a Bosch remaned unit, $130 new from Pep Boys w/lifetime warranty.