headlights cause voltage drop!

[DCx]

im having electrical problems since the install of my carbed ls1. here is a thread i posted on ls1tech about my electrical problems.

http://www.ls1tech.com/forums/showthread.php?t=994010

any help would be appreciated.

[woody80z28]

I'll bet relays for your headlights would help. Take your current feed wires and make them the open/close circuit and run direct alt power to the load circuit.

[DCx]

i thought the painless fuse block had built in relays for the headlights? or would i need to add more?

im wondering if i have a crappy reman f body alternator. im currently on my second alternator. do you think a 130 or 160 amp would be better?

with just the fuel pump running while the car is warming up best i get out of it is 13 volts. i never had these problems when my gen 1 small block, but then again i wasnt running an electric fuel pump either.

[FULMNTE]

Painless wiring harness does not have relays for the headlights (at least the one I put into my A-body did not have them).

Check this out:
http://www.culayer.com/Matchbox.htm

[DCx]

i will invest in some relays and see if running the lights directly from the battery will fix the problem.

i never knew i had this problem with my old SBC because it was all mechanical. as soon as i added the fuel pump and f body fans it all went to hell.

[DCx]

painless has been good to me. i think i will give this a try. im using a pre wired (3) bank of painless relays for my fuel pump and ls1 f body fans.

http://store.summitracing.com/partde...5&autoview=sku

[GetMore]

I didn't read the whole thread on LS1, but once you listed one main ground wire to the block and a small one to the other location it raised a flag. You need to have a large enough ground wire to handle all the power the alternator can put out. Add a second large ground wire from the body to the battery and I think you'll fix your problem.

[DCx]

at the moment i have a 2 gauge battery cable from the battery to the block and a small copper ground wire from the intake to the wiper motor.

[DCx]

i added more chassis grounds. added a braided cable from the block to the frame and another from the negative terminal on the battery to the core support.

I also swapped in my 4th Fbody reman alternator and got one that will change! The headlights still cause a minor drop without the relays, i will add those next.

[DynoDon]

Relays won't change a voltage drop dramatically unless it is running through old crappy wiring or switches. What the relay's do is take the high draw out of the switch and wiring and run it more direct from the battery. There will be a small change, but not drastic.
The comments about grounds are very true and that is more critical with all the new electrical items you are running. Check the grounds at the headlights themselves as well and if they are grounded to the core support, make sure it is grounded to the frame.
Fans and EFI fuel pumps can both be Very large draw items and they need good grounds and large gauge feed wires.