FYI - High Output Alternator

[BigDaddy13440]

Having a charging problem with my XL lately, I think the alternator is working intermittently. It'll charge the battery while driving, but if the truck sits for more than 2 hours, my voltage is down to under 10, and I have to use a jump-pack to get it going. So, did a little research on alternators:

2004 GMC Sierra 3500 trucks have the exact same part numbers as ours for the factory 105 and 145 amp alternators. Advanced Auto and RockAuto both have an optional 253 amp alternator, new, for less than some of the remanufactured units at either place. Found mine on E-Bay, no core required and with shipping included, for $115 - at Advanced it was about $250!

https://www.ebay.com/itm/H2-Suburban-ALTERNATOR-253-AMP-97-98-04-HIGH-AMP-HD-High-Output/352212758226?ssPageName=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

I'm starting with the alternator, as I'd replaced my battery back in August. If the alternator is good, then I might have a bad battery. If that doesn't cut it, then I'm going to disconnect all my accessories and then reconnect them one at a time, until I find the culprit.

 

[iamdub]

If the alternator is charging and keeping the voltage around 14V while the engine is running, then it should be good. Sounds like the battery isn't holding a charge or you have something draining it very quickly. New batteries can be defective, especially if it's an Autozone house brand battery. You can quickly test the draw on the battery with a cheap multimeter.

 

[Doubeleive]

that's a decent price I paid $209 for a 300 amp a few months ago

 

[BigDaddy13440]

If the alternator is charging and keeping the voltage around 14V while the engine is running, then it should be good. Sounds like the battery isn't holding a charge or you have something draining it very quickly. New batteries can be defective, especially if it's an Autozone house brand battery. You can quickly test the draw on the battery with a cheap multimeter.

I had it tested, sat at 12V with the key off. 14.2V with the key on, and dropped to 13.4 with all my accessories on (including the stereo, with a Lightning Audio 1001.d mono amp).
The new battery is from Autoparet International, one of Advanced Auto's suppliers.

When the 253 amp alternator arrives, plan on doing dual batteries, with 1/0 wiring between batteries (also bought a 1/0 lug crimper) - already have the Big 3.

 

[iamdub]

I had it tested, sat at 12V with the key off. 14.2V with the key on, and dropped to 13.4 with all my accessories on (including the stereo, with a Lightning Audio 1001.d mono amp).
The new battery is from Autoparet International, one of Advanced Auto's suppliers.

When the 253 amp alternator arrives, plan on doing dual batteries, with 1/0 wiring between batteries (also bought a 1/0 lug crimper) - already have the Big 3.

Yup- sounds like the alt is doing fine. I'd make sure there's nothing draining it. Losing 2 volts in 2 hours is a big drain.

 

[SnowDrifter]

Pretty standard for ebay alts. Cheap high output alts are absolute dog shit. Get a good brand like Singer, Mechman, or DC Power. Pricey, but you get what you pay for

 

[BigDaddy13440]

Pretty standard for ebay alts. Cheap high output alts are absolute dog shit. Get a good brand like Singer, Mechman, or DC Power. Pricey, but you get what you pay for

It's not a cheaply-made, hopped up alternator meant for car audio. It's a direct fit for a Sierra 3500 series, it's an option available from the factory. Even if it ***** the bed in a year, I'm have it under warranty for that long

 

[rockola1971]

I had it tested, sat at 12V with the key off. 14.2V with the key on, and dropped to 13.4 with all my accessories on (including the stereo, with a Lightning Audio 1001.d mono amp).
The new battery is from Autoparet International, one of Advanced Auto's suppliers.

When the 253 amp alternator arrives, plan on doing dual batteries, with 1/0 wiring between batteries (also bought a 1/0 lug crimper) - already have the Big 3.

Nobody else caught this? Battery voltage was at 12v with key off but with key on the battery voltage went up to 14.2v? You have that backwards?

 

[iamdub]

Nobody else caught this? Battery voltage was at 12v with key off but with key on the battery voltage went up to 14.2v? You have that backwards?

I assumed by "key on", he meant with the engine running. The battery shouldn't be 14V by itself.

 

[BigDaddy13440]

I assumed by "key on", he meant with the engine running. The battery shouldn't be 14V by itself.

Yep