Amp Calculations for Alternator

[Zaphod]

Okay, so I add up all the lights and stuff I'd like to mount on my truck someday, and I get 615W:

2 PIAA 85W Fog Lights = 170W
3 ProComp 130W Lights = 390W
1 ProComp 55W Light (rear-facing) = 55W

170+390+55=615W

BTW, this doesn't include 1 Warn 9500 Winch at 650 cca (whatever that means), the CB radio, whatever may be plugged into the interior power ports at the time, and the existing factory loads in the truck.

Now, the biggest alternator I've seen is the Mean Green one at around 300 (?) Amps.

So, how many amps do I need to be able to run all this stuff? Chances are I'll never run it ALL at the same time, but I like knowing that I CAN in a pinch.

Gearhead+Newbie=Danger!

Heavily modified since I got Amps and Watts confused!

[Eric]

Figuring 170W at 12V is a little over 14amps for your fogs.

Your 3 ProComp lights would draw roughly 32amps max.

The rear light would draw roughly 4.5 amps.

All of that together would be almost 50amps. You're probably okay on the stock alternator for awhile, but I'm thinking it's playing catch-up after a couple hours or so. That's all assuming it's running the whole time.

Engine turned off, I dunno. I'd put it somewhere at a half-hour you could run all of that, except for the winch, before you're really looking at the battery being out of commission.

I found a link for an Isuzu 150amp alternator today. $300.

It's really hard to say. It would be way cool to run a barrage of lights up front, at least one to the rear, and maybe one to each side off of the roof rack. I'm just wondering how long our lil' alternators can keep up with all of that.

Almost killed my alternator this weekend while 'wheeling. Just got my LTBs on, and playing around in the mud, got stuck for the first time. A K5 blazer was there to pull me out, but I managed to fill the alternator with mud. Turns out they don't like that....

Had a quote from Advance Auto for $238 plus tax and refundable core charge for an alternator for a 6VE1 ('98+ Trooper/SLX/Axiom/VehiCross).

My buddy Mike Caffey cleaned the hell out of it with some dialectric solvent, and we threw it back in and it worked. I owe him big time.

So, I bought him pizza.

[Zaphod]

Thanks for reminding me that Power = Voltage x Current (P=IV). I had forgotten! ;D

Curious: Why would you run lights to the sides? I was expecting to use the rear light as a work light rather than as a navigation light.

Either way, the upgrade looks like a good idea. If you're running that kind of wattage, you want to ensure you've got the juice to feed it, and a little extra. If you wire in an extra battery, the need increases.

Considering what frying the factory alternator costs, it seems smart to do the upgrade and then sell the factory unit to recoup some of the costs.

Thanks for that link, BTW.


Edited to add: The website you linked to identifies the factory alternator as generating 80-90 Amps. Maybe there's enough in there after all...

NAH!

[dieselbob]

Something else to keep in mind is the capacity of the factory wiring. Assuming you would run the lights and winch from the battery, there are only 2, 12 gauge charging wires running from the alternator to the main fuse ( 80 amp ) and then to the battery. ( This is how my 2002 Trooper is factory wired. ) If you take that 12 gauge wire is capable of only 20 amps continuos current and you have 2 of these wires then your limited to around 40 amps of continuos current before you would start to overload the factory wiring. One solution to this problem would be to run a 4 gauge wire from the alternator through a diode to the battery. This would allow for much higher charging rate to the battery and allow the factory wiring to take care of the vehicle needs.

Just my $.02

[Zaphod]

Sigh......so much to learn!

Thanks for pointing out what would have been obvious to me were I wiring a house!