Alternator/Voltage problems

[99Tahoe]

Hey guys, Im having some annoying problems that i beleive are coming from my Alt.

My truck has an original 105 amp alternator in it and when my truck is in park, idle, the voltage drops when i do anything ie, turn ac on, lights on, power windows. The voltage drops from around 14 to 12 and the lights dim or the ac slows down. However, Whenever im at high rpms and driving, none of this occurs until i come to a stop. To be honest, none of this really mattered to me until i got a sound system with an amp and speakers and headunit.

My lights began to dim like crazy so I upgraded the Big three and the voltage didnt drop that day. Next day, My car wont start so i go in and get the battery tested and its putting out nothing so i get a brand new one(nothing nice, just the biggest one they had at walmart, everstart or whatever).

My voltage wont drop and lights dont dim heavly with bass for about 2-3 weeks. Now, I upgraded to a new amplifier and subwoofers and my lights dim like crazy and they do even with the amp off and turing on ac and such things. I decided to get a new 105 alt and see if it would work and im having the exact same problems and im out 120 dollars and have two alts. I called around and got an estimate to rebuild my old alt to 140 amps for 100 or 200 amp for 200 dollars...

What are your suggestions or advice on this.

 

[TigerEyz3]

Multi-fold...

1. Your electrical needs (factory electrical needs plus amps) have increased beyond the stock alt's ability to recharge the battery. This is most likely why your battery died - not enough juice to recharge it fully.
2. The reason you only notice the voltage drop at low rpms is because the stock alt puts out 105a MAX- when rpms are 2k+!!! At idle, you're lucky to get 1/3 to 1/2 of that.
3. When your alt is sufficient to power ALL of your electrical needs, you'll read 14.4V when engine is running (not 12V - which is what you'll get from your battery).

I'd personally suggest a ** alt - you'll get more juice at lower rpms (not only absolute numbers, but greater % from the alt at lower rpms). The size of the alt you'll need is going to be a function of what you are trying to power electrically. That said, I've got a RF 800.2 channel amp power a set of 12s. I'm using an Iraggi 220a ** alt and an Optima Red Top (big three are upgraded) and have no problems with voltage whatsoever.

 

[99Tahoe]

How much did you pay for that alt and what did you have to do to install it? Just perfect bolt in or did you have to make modifications and change the pulley?

 

[TigerEyz3]

It's been many years ago since I purchased the alt - not sure of his current pricing. I'd suggest you contact Dominick directly (info below). As far as install, you don't have to worry about pulleys at all - it comes with the necessary pulley. There's a bracket that you'll need (I bought the large case alt that has 3 lug ears compared to the 2 that are factory on the small case) - he can supply that as well.

Dominick Iraggi
[email protected]
615-287-7991

 

[blueflamed03]

yep, need a bigger alt. Most will charge more during higher RPMs, but will decrease at idle.

Also, you could cause damage to your sound system if the voltage drops 'too' far...

 

[AtomicHoe094]

you could drive getting a overdrive pulley for the alternator. But look around locally and see if any places rebuild them and beef the hell out of them.

 

[atis]

ok, dumb question warning..... what the heck is the big 3??

 

[SunlitComet]

it means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis.

Usually done by replacement with bigger and better cables.

 

[atis]

check...that makes sense