76Vett

I recently installed a Dewitts Radiator with dual fans. Now the battery gauge jumps to the positive side when the fans come on, almost pegging out. What does that mean exactly and is it a problem?

MakoJoe

It could be since you added Electric fans to the cooling system your Altenator is overworking to compensate for the additional load. On a 1976 Vette the Altenator is I think rated at 68 AMPs. To fix the problem you may need to go to a 85 AMP or 140 AMP Altenator to handle the additional load.

http://www.ecklerscorvette.com/engin...enerators.html

7T1vette

It means that the wiring you used to hook up the fans is NOT interconnected with the main harness that supplies power to the rest of the car. So, your ammeter DOES show that the alternator is sending out current to replenish the battery; but it does NOT show the actual current being drawn by the fans.

This is not really a problem, as long as you understand what the gauge is showing. But it does beg the question of how you are feeding that current to the fans?

76Vett

7T1vette - My main power source is from the starter (yellow wire). The orange wire is connect to the wiper motor and only hot when the key is on. Black of course is grounded. Gray wire is to the thermostat sending unit. Red wire goes to fan. These are the color wires from the relay supplied by Dewitts (SPAL). Some have suggested that I get my main power (yellow wire) straight from the battery, I'm not sure that makes a difference. Others have said that I need to upgrade my alternator (presently stock). Everything works as it should, fans come on and off as needed. Just concerned about the battery (ammeter) gauge and don't want to ruin it. I hope this makes sense.

DUB

76Vette,

For what it is worth:

When ever I install ANY aftermarket electrical component that was NOT installed by the factory. So a normal in dash stereo/cd player I would use factory wiring...because there already was a radio from the factory at one time. In this case...an electric fan that was NOT factory. I pull 12 volts from the battery...even if I have to get a gold plated terminal cable bolt that allows power and grounds to be taken off the battery cable terminal bolts. The same would take place if it were an aftermarket ignition system (MSD).

I know many feel that pulling off the starter solenoid is acceptable....and that may be true and work...but I believe in connecting at the battery.

Also pulling your ignition power off the wiper motor is something I would not do. The reason being ...if the wiper fuse blows...your fan will not work. I would find an UN-FUSED ignition wire and then attach the relay wire to it...and have a in-line fuse in it to protect the relay. I usually pull the circuit off the wiring that goes to the ignition switch mounted on top of your steering column....or the wiring going into the fuse panel...and mount a remote fuse holder there or someplace easy to get to. YES...it is a pain...but I myself can not afford an installation to fail due to incorrect wiring. All connections are soldered and shrink wrapped....and this includes any crimp style connectors. They are soldered and I cut off the plastic sleeve off and shrink wrap them....so they look factory and you do not see that yellow, red or blue insulation sleeve on the end of the connector.

Also...you have to remember...if you are adding components that draw a large amp load...you might want to upgrade your alternator. Because I figure out what the amp load would be if you were driving at night...with high beams on...the wipers on and radio playing...and the cooling fans operating. Figure out what the max load on the system would be if as much as possible was powered up....then make a determination from that.

DUB

MakoJoe

I respect Dubs opinion on this also While I did not need to call him with an electrical problem last July he offered me his phone number to call him while I was Diagnosing an electrical the problem. In my case it turned out my battery drain was in 2 places the Under Hood Courtisy Switch and the Horn assembly were bad when I boought my 1977 this year. Using his post to me in steps to figure it out I was able to overcome the problem. I gave him hints he gave me back places to look and resolve the problems. I was grateful when he asked me to call him if needed.

You cannot go wrong with upgrading the Factory Alternator to 85, 100 or 140 AMPs to fix your problem. The Alternator has a voltage regulator built into and if you buy one far more than you need it will regulate the voltage and not overcharge the system.

Kim72

I have the same situation as the OP. Can the existing alternator be rebuilt to pump out more amps or is a new one needed?? I'm considering "more power" (amps) to help with this issue.

doorgunner

In case no one mentioned it yet.......

a 140 amp alternator solves any problem with cooling fans/etc (but, like the other members said---You HAVE to use relays that are supplied from the proper 12V sources)

You need to replace the "charging wire" that sends voltage from the alternator to the battery---replace it with a "heavier gage" wire so the battery will be properly charged/the alternator won't be "stressed-out"/the charging wire won't overheat.....

been there---had all those problems!

Kim72

Doorgunner: you make a good point. I already have my fans (2) on relays, wired directly to the battery, so that is not a concern. It works well. I will have to consider the original wiring if I upgrade my alternator.

John 65

That is how mine is set up. Alt is 100 amps, and zero problems. I ran a black battery type cable from the alt to the starter and it works fine. Fused fan relays from the starter also.