[Godchaser490]

Well I'm building a light bar and I am worried about any side effects of pulling so much juice from the alternator. Right now after the bar is installed I will have:

HO stock lights from GE
2- 55w cheepo baja's
4- 100w cheepo rally's

a quick run through the math and that's an extra 510watts over stock for night wheeling.

What I am going to do is upgrade the alternator and battery cables to 2 guage but is there anything else? Will this kill the life of my alternator?

[KaiserJeep]

Upgrading the battery and alternator cables is a good idea, but it is essential to upgrade the wiring to the lightbar. I personally would run a single 4-gauge cable to the lightbar, then mount a seperate fuse panel (Buss makes one for ATO fuses available at most Auto Parts places) and a single relay for each pair of lights, in a small box ON THE LIGHTBAR. All the heavy wiring is thus up on the bar. Run a single small 4-conductor cable down to some switches to pull the relays, use one wire as a common ground and the other three to operate the relays.

[SirGCal]

Originally Posted by KaiserJeep

Upgrading the battery and alternator cables is a good idea, but it is essential to upgrade the wiring to the lightbar. I personally would run a single 4-gauge cable to the lightbar, then mount a seperate fuse panel (Buss makes one for ATO fuses available at most Auto Parts places) and a single relay for each pair of lights, in a small box ON THE LIGHTBAR. All the heavy wiring is thus up on the bar. Run a single small 4-conductor cable down to some switches to pull the relays, use one wire as a common ground and the other three to operate the relays.

Little overkill there Kaiser? 4 AWG for 400W lights? Your only talking (including wased power and all) about 60A total in the worst conditions (@ 34A in ideal conditions)... 10 AWG would be fine for the short distance involved even for all four. I wouldn't put the relays up on the light bar either. That runs an always hot lead where it doesn't need to be. I'd put the relays somewhere around the battery and run a pair of 12 AWG or 10 AWG wire up to the lights.

For just those lights, you probably won't have to do an alternator upgrade, but if you add much more (and use it at the same time) you will probably need one. But I would definatly get a good deep cycle battery.