Ok im definitely going to upgrade my alternator, since my volt meter on my gauge drops to about 12 when both the fans are on sitting in traffic at idle. This is also a constant drain, it does not go down and then back up it stays at 12v on the gauge. Now ive heard about people having the 145 amps and still having power drain. However does it go back up after the initial draw or does it stay low like mine at idle with both fans on. If so, do you think a 200 amp alt would be enough to stop the drainage problems.

 

I have the 05 fans and the STOCK 105Amp alternator, The initial power demand is around 75amps on start up of the fans on high. My volt gauge and DMM meter to back it up, drops to 11-12 volts, then goes back up to 14 after the inrush amperage settles down to 6-7 amps on high. This is with the stock battery too. There is no problem with this. If you have power windows, try to put them both up at the same time when the windows are already up and your lights will dim too.

The only way to avoid this is with two optima batteries and a huge 200+amp alternator. To be honest it is not worth it to spend that kind of $$$ so the lights don't dim.

This is my opinion and you can do with it what you want, there is nothing wrong with the lights dimming. If it bothers you and you have $$$ to burn then go for it.


I'm not trying to be an *******(I really am sorry) this is just getting old and I'm tired of it.

 

ok now when u are sitting in traffic this urs goes all the way down to 6-7. Now when u say ur lights dim, do they stay dim while u are in traffic and then go back up when u are going, or does it just dim for a little then go back to normal.

 

When your at a dead stop in traffic at around 500 rpm and the fans kick on high from low(AC trigger) then the lights will dim slightly for a second then go back to normal with the fans still running. The voltage will drop from 14v to around 10-11volts, then go back up to 14 volts.

I have measured the fans will draw 75+ amps when going from slow speed to full(temperature trigger only and then adding the AC trigger), but when they reach max speed the amperage will drop to 6-7 amps, and the lights should return to normal.
I will try and get a video tonight if I can remember.

If you lights stay dim then you may have a high amp draw sound system, a bad altenator(if you have sprayed water on it for cleaning it WILL damage it) or maybe a bad bettery.

 

o ok i will have to check it out, but anyways doesnt the alternator do all the power supply anyways when the car is running, so does the battery even have anything to do with this problem?

 

The battery is a "shock absorber" for the electrical system, so it could cause the problem.
BTW. I have a 105a and 05 fans, My voltage drops to 12.4 at idle with the fans on high and stays at 12.4.

 

Just remember that when your lights are diming so is every other electrical item on the truck! That means that even the ignition is getting a hit! A proporly set up electrical system will not dim the lights, it may seem like a waste for a $200 alt but, it is well worth it in the long run...

 

Ok thanks for all the help. Now I just need someone with a 145 amp to tell me if the volts stay low at idle with both fans on high or does it go back to normal.

Hey Wilde, do your lights dim while at night and stay dim until you start driving? thanks