Headlight upgrade

[glider]

I am trying to get more light for driving. I have the GT light bar with 55 watt lights. I was on the phone with my local parts store they said they have a replacement 100 watt bulb for 5.99 a piece. Anyone tried those? It if works it would be a good cheap upgrade.

[dukhuntr]

I think several people on here have done it, but I personally have not.

[ArmyHunter]

I think HuntnDux has posted about it and when I met him he told me was going to change his bulbs in his GT light bar to 100watts. The only issue he said he would have is that since his battery is up front and the switch panel is in the back he would have to re-run new heavier gauge wire to handle the draw.

[huntn'duxx]

I did replace mine. When I took out the 55's and put in the 100's the light may as well been a lantern on the front. I thought the problem was the wiring, but it was unexpectedly 10 ga and was ok. Their was a definite voltage drop after the lights were plugged in. I was getting 12.5 volts at the plug where the lights plug in but as soon as I plugged in the lights with the 100 watt bulbs the voltage dropped to 7.5. I was working on it with a buddy of mine that is a crane mechanic for H&E Equipment and he suggested a relay since the existing wiring was big enough to handle the load. We added a 70 amp relay mounted to the bulk head under the front deck that gets a constant 12v feed from the battery. We also learned that I needed to run my batteries parallel so that when the motor was running at 2000 rpms or better I would get more amps delivered to the accessory battery thus increasing voltage. In the past I have run one battery for the motor only and one for the accessories, thus only one battery gets charged when the alternator is putting out amps. When the motor isn't running I am getting about 10 volts at the lights running through the relay. Oddly enough voltage picks up as soon as the motor is started even though the altenator doesn't start producing amperage until you reach about 2K. When I ran the motor up to about 3K we were getting 11.5 volts at the lights. Long story short is it's not as simple as just replacing the bulbs. Luckily for me my buddy had everything we needed to complete the job. Otherwise it would have cost a few bucks, but I have no idea how much. I drew up a diagram with "paint" but the file is to big even after I've resized it.

[foldem]

i just replaced the bulbs and it works great, my battery is not in the front.

[glider]

The wire was big enough but the switch wasn't carrying enough current? Did you put the relay in the switch box? And then use existing wires?

Just saw Foldem's post. My batt is more or less in the rear. I went ahead and put the bulbs in mine as well. I will really have to try them on the water to see if they made any difference.

[glider]

There was a slight difference in the bulbs I bought. I bent the extra tab and they went in without problem.

[huntn'duxx]

Originally Posted by foldem

i just replaced the bulbs and it works great, my battery is not in the front.

There in lies my problem. The current was traveling 30' before it was ever put under a load. Then once plugged in everything went to crap. I was getting 12.5 volts at the plug, but only 7.5 at the lights when both were hooked up. And there's only 12" of wire between the plug and the lights. It's amazing how big of a load those lights put out. I didn't ever put a meter on the connection at the lights when the 55's were in but I would bet that it wasn't getting 12 volts unless the motor was running at pretty good rpms. Of course I am basing this strictly on what I saw with the 100's, which could be totally off base.

[huntn'duxx]

Originally Posted by glider

The wire was big enough but the switch wasn't carrying enough current? Did you put the relay in the switch box? And then use existing wires?

Just saw Foldem's post. My batt is more or less in the rear. I went ahead and put the bulbs in mine as well. I will really have to try them on the water to see if they made any difference.

The bulbs I bought had to be modified the same as yours.

My batteries are up front under the front deck. Voltage was fine until the lights were plugged in. The load was just to much. I mounted my relay on the bulk head that separates the extended deck from the front deck storage.

[deadbird8]

Originally Posted by huntn'duxx

I did replace mine. When I took out the 55's and put in the 100's the light may as well been a lantern on the front. I thought the problem was the wiring, but it was unexpectedly 10 ga and was ok. Their was a definite voltage drop after the lights were plugged in. I was getting 12.5 volts at the plug where the lights plug in but as soon as I plugged in the lights with the 100 watt bulbs the voltage dropped to 7.5. I was working on it with a buddy of mine that is a crane mechanic for H&E Equipment and he suggested a relay since the existing wiring was big enough to handle the load. We added a 70 amp relay mounted to the bulk head under the front deck that gets a constant 12v feed from the battery. We also learned that I needed to run my batteries parallel so that when the motor was running at 2000 rpms or better I would get more amps delivered to the accessory battery thus increasing voltage. In the past I have run one battery for the motor only and one for the accessories, thus only one battery gets charged when the alternator is putting out amps. When the motor isn't running I am getting about 10 volts at the lights running through the relay. Oddly enough voltage picks up as soon as the motor is started even though the altenator doesn't start producing amperage until you reach about 2K. When I ran the motor up to about 3K we were getting 11.5 volts at the lights. Long story short is it's not as simple as just replacing the bulbs. Luckily for me my buddy had everything we needed to complete the job. Otherwise it would have cost a few bucks, but I have no idea how much. I drew up a diagram with "paint" but the file is to big even after I've resized it.

I resized the files and here are the diagrams from H-duxx:

[huntn'duxx]

I may be wrong about the positive going from the switch to the relay and then to the plug. It may go straight from the switch to the plug, because the relay is getting a direct 12v feed from the battery. At one point I was completely lost as to what we were doing so I left it up to my buddy that was helping me out. GunDoc is pretty up to snuff on these things since the electrical system in his rig is wired like a "mother board on a computer", so I'm sure he can answer questions about it better than I can.

Thanks Gary for posting the diagrams.

[BUCKWILD]

I purchased the 100 watt bulbs from Autozone. They did not have the extra tab on the side like the ones in the pic. Also, there is a 10 amp fuse in the male 12v plug that may need to be increased. I figured 4.2 amps with the 55watt bulbs and 7.6 with the 100 watt. That was calculated with 13 volts. I went with a 15 amp fuse.

[glider]

Thanks for the heads up with the fuse. I used mine a few times and there is definitely an improvement. I also went ahead and cut out the grid that covered the light. Don't know if it helped much or not. The mod seems to be worth the investment.

[willydiver]

Aren't relays great!