Voltage problem after Tower light install

Maybe this is a common problem, but figured I would ask...
Before I installed tower lights on a 04 Malibu VLX, I upgraded the stock 70 amp alternator to a 120 amp after market. Not sure of the brand, but this guy is very highly recommended from the boat dealers.

I do not run a heater in the boat, so I used the extra accessory switch on the dash that usually handles the heater (30 amp breaker I believe).

Problem is that the voltage drops significantly when running the tower lights even at high RPM's. The other night on the lake (around 1400 RPM), I had my docking lights, tower lights, and stereo on at the same time. The voltage dropped so much that it started beeping and flashing "BATT" on the computer, due to insufficient juice from the batteries. I always charge the batteries before the lake. These batteries are 7 months old.

I'm running two blue top optima’s and the "Fusion 6 Light Bar". I'm wondering if this is a wiring problem from the tower lights or the Alternator still isn't big enough. I used the same size wires that matched the pre-wiring of the tower lights.

I will hook the hose up and run it on the trailer tonight with a volt meter to give you further details. Shall I measure voltage drops at idle or at a certain RPM while turning on the lights? By viewing the stock analog volt gauge on the dash, it looks like it drops from 14 to 10 volts while at an RPM of 1,100.

if it matters, which i'm sure it does...

Audio setup:
Punch 300.1 (@ 2ohms)
Punch 300.2 (@ 2ohms)
Punch 400.4 (@ 4ohms)

Where did you get the power for the lights. I always run at least a 10 ga wire directly from the batt to the swich. If using the factory wiring it might just be bleeding more power than the supply to the dash can keep up with. I have had problems with the malibus not having good power at the dash before.That light bar has the ability to pull up to 55 amps of current if my memory serves me correctly. Try running a fused 10 or 8 ga wire from the battery, or perko, if you have one directly to the power input side of the swich and see if that helps. If it does then run the wire in a neat and orderly fashion to make sure nothing accidently catches it. Also run the same size ground wire directly to the batt.

Thanks Chris, I will run a temporary 8 or 10 ga pos/neg wire and see if that's it. That's an easy troubleshoot... Come to think of it, I might only be running 14 ga for both wires.

Good luck. If you got any more q's just post em up.

Chris,

I might have had it hooked up wrong... The wires "stock" off the light bar are 14ga and had them running directly to the fuse box with the accessory wire (white), running to the switch. because the stock MFG wires were smaller going out of the switch, this might have been the culprit of "bleeding power", but not sure..?? I also noticed that the wires were VERY warm for having the tower lights on for 5 minutes (almost hot), before I tried the new 10ga hookup. I cut the Pos & Neg coming off the light bar and ran 10ga directly to the Pos & Neg post on the battery. I then left the white wire plugged into the switch as it was before and it appears to have solved the problem.

I haven't tried this out by running the boat. However, I've only tried it out by turning the key to accessory and monitoring the analog volt gauge in the dash. It goes down a tiny bit when the lights get turned on, but doesn't appear to be as dramatic as before.

I hope this is still the correct way to wire it..

Sounds pretty close. Sounds like if the wires were getting that warm you were just overdrawing them. My recomondation is this. leave the acc wire to the swich input. Run the output of the swich as a trigger for a relay. Run a 10 ga power and ground to within a few feet of the tower wires coming into the boat. Hook the ground directly to the tower lts. Hook the positive to the common on the relay. Hook the positive from the lts to the normally open of the relay. Splice a ground off the ground connection to one side of the relay coil, and the positive from the swich to the other side of the coil. Use the relay to power the lights. If you need a drawing get me a fax # and I will draw it up and get it to you. You also want to make sure the wire in the tower is of sufficient size also.

(Message edited by audiopro74 on March 15, 2007)