electrical needs of mty c10

[dec010974]

hello to all. I have a 1971 c10, stout, fuel injected 370 lq9/th400 with air ride suspension, 2 Viair air compressors, walbro electric fuel pump, custom dash with autometer gauges, and dual electric fans. I plan to add AC in the near future. I want to address my electrical needs. lets say, hypothecally that I want to power all this at the same time. how can I ensure the each unit is getting all the power, it needs. my first step is to upgrade the alternator and battery, right? powermaster 255 and a yellow top optima battery? what some your tricks?

[Andy4639]

Originally Posted by dec010974

hello to all. I have a 1971 c10, stout, fuel injected 370 lq9/th400 with air ride suspension, 2 Viair air compressors, walbro electric fuel pump, custom dash with autometer gauges, and dual electric fans. I plan to add AC in the near future. I want to address my electrical needs. lets say, hypothecally that I want to power all this at the same time. how can I ensure the each unit is getting all the power, it needs. my first step is to upgrade the alternator and battery, right? powermaster 255 and a yellow top optima battery? what some your tricks?

Relays are your electrical power system friend!

Anything requiring large amp draw put on relays.

[Clyde65]

Stock AC compressor or aftermarket?

[dec010974]

sanden possibly. I have relays on every thing such as fans, viair compressors, ignition, fuel pump. at night, when the lights are are on the seem dim. I expect them to be brighter. what battery would a good power source to tar with? nice truck Clyde65. 4.8/4l60E, good, proven drivetrain.

[Bigdav160]

The fans are the big power hogs. You could be pulling near 50 amps when their on.

I'd have the headlights on a relay also.

[dec010974]

interesting. put the light on a relay. if you don't mind explaining, how will this helps?

[VetteVet]

The wiring on these older trucks is a fairly small gauge and as they get older they develop more resistance to current flow. In addition to that the switches become overheated from carrying the current and they gradually burn out.
Headlight, heater, ignition and dimmer for instance.

What the relays do is carry the high current loads in the truck circuit. The vehicle switches then just turn on the relays instead of the loads directly.
It takes just a few milliamps to turn on a relay as opposed to turning on a fan or a light. The voltage required to do that is much much less than what is required to operate the headlights or the heater motor.

The result is a much smaller voltage drop in the circuit and more power for the
lights and the fan. This means brighter lights, more current for the fan motor and anything else on a relay circuit.

The headlights are operated by a main power wire going to the headlight switch, 12 gauge red and a 12 gauge blue wire from there to the dimmer switch. From the dimmer switch we have 2 smaller wires, Tan ( low beam ),and green, (high beam ) that run directly to the headlights to the left and then over to the right. These small wires carry the full current load to the headlights and the voltage drop over all that resistance can be as high as 2 volts. So you have 10 volts for the headlights instead of 12.

Here's what we do to cure the problem.
We run 12 volts through the relays for the light power over a much shorter distance result brighter lights and less dimming at engine idle.




Notice the 12 volt power to the relays to terminals 30 and the exit power to the headlights from terminals 87. The terminal 30 wire is fused by a 20 amp fuse, for each headlight.

The relay coils then become the controls for turning on the lights.
We run the tan wire to the no. 86 terminal and then ground the 85 terminal to a good solid ground. Now we have the low beam circuit completed.

We do the same to the light green wire on the other relay for the high beams
and marvel at the brighter lights.

The wires in the diagram are different colors but than stock but we can substitute the correct colors using the tan and green and of course black for ground.

Be sure to clean and tighten the headlight connections and the grounds.

For you GM guys we have a slightly different diagram.

[BR3W CITY]

Mine has been fully rewired, but I echo the sentiments above. Making sure you have a good thick gauge wire for power feeds or anything that has a high constant draw, can really make a difference. The old solid core stuff can easily be overpowered and melt down.

[dec010974]

well br3w and vettevet, I fully understand. my electrical was rewired. well I just thought that since I rewired my entire truck with a new electrical fuse box that the wiring should be up to par. I even thought about using the new leds which I know run on a relay system. thanks for the info. this will be my next assignment on the truck. this shouldn't interfere with my t56 funds.