How much extra load availabe?

Shdwdrgn

Original poster
Member
Dec 4, 2011
568
I'm planning out a new lightbar for my roof. Currently I run four 55W lamps, which doesn't seem to be a problem, however I am planning on adding another pair of 55W lights, and a pair of 100W lights. All together, the light bar will draw 530 watts (just over 44 amps). My only concern is how much power the stock alternator puts out... Does it have the capacity for this additional load, or will I be slowly draining my battery when I flip on the brights?

This is a 2004 TB SWB.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
The 4 55 w lights dont seem to affect anyone, but not sure about adding more than that.
 

Regulator

Member
Nov 20, 2011
2,496
I am running 6 55w's, 4 on the roof and 2 on the bumper, and have no issues with draw down.
 

MrDJ

Member
Dec 4, 2011
180
Waxahachie, TX
Regulator said:
I am running 6 55w's, 4 on the roof and 2 on the bumper, and have no issues with draw down.

For your lights on the roof, are they spot beams or flood beams?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
The alternators are all 150A. I haven't measured the baseload current required by the vehicle (I could do that with my DC clamp-on ammeter), but you certainly have 75 Amps or so available for peak draw, which is about 900W. You might have a problem if you tried to raise or lower all FOUR power windows at a time with the lights all on. With the electric defogger also running. Even if you did use battery power when at idle, you'd be making it back up at higher RPM. Just watch the voltmeter.
 

Regulator

Member
Nov 20, 2011
2,496
MrDJ said:
For your lights on the roof, are they spot beams or flood beams?

The roof lights are floods, the two 5" rounds on the bumper are driving lights.
 

MrDJ

Member
Dec 4, 2011
180
Waxahachie, TX
Regulator said:
The roof lights are floods, the two 5" rounds on the bumper are driving lights.

Okay. I am really wanting to put 4 lights on the roof sometime soon. I want to build a roof rack but I am not good with building stuff like that. I can get spot beam lights for $8 each but the flood beams are at least double that. I might get spot beams to see if they will work but I don't know yet. I need a rack first.
 

Shdwdrgn

Original poster
Member
Dec 4, 2011
568
Roadie - That's great info, thanks for that! I doubt there will be any lengthy periods of running both the flood lights and the fog lights, but I just wanted to make sure I'd be ok if I did turn everything on all at once. I figure I have a 25A breaker/relay running my current four lights, so I'll add a second set for the two 100W lights, and one more relay and 10-15A breaker to tie the additional fogs into my existing factory fogs.

I have a complicated idea for my new light bar, but I think I've figured out how to build it. I want to go with an oval shape, approximately 2.25" tall and 3" wide. However I also want the bar to be curved so that the outer lights are aimed out towards the sides a bit, but the light lenses are flush to the surface of the light bar. I don't have access to the right equipment to make a smooth large-radius bend, but I do have a welder. My plan is to cut a 3" hole into a thick piece of wood, then split that in half and clamp the halves together. Next I cut out two arcs from sheet metal to the radius that I want the bow of the lightbar to be. I can use a hammer and pound the sheet metal into half-pipes using the wood blocks for the form. These will form the top and bottom of the lightbar shell. For the back of the shell, I'll slit a piece of 2" pipe to give me about 1/3 of the circumference, then hammer this piece into the arc of the overall shell. A bit of welding and finishing, and I'll have a shell with the oval shape and sweeping arc. The front will be completely open, and I can position my lights and weld metal strips down the front as spacers between each light. I'm trying to decide if I want to make metal caps for the ends, or heat-form some orange reflectors and put lights behind them to make running-lights. Once its all finished, I'll get it powder-coated.

It'll be quite a bit of work, but it will certainly be unique! Of course this would be a lot easier if I could just find a place that could mandrel-bend a chunk of pipe for $100, then I could hammer it down into the oval shape myself.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Shdwdrgn said:
It'll be quite a bit of work, but it will certainly be unique! Of course this would be a lot easier if I could just find a place that could mandrel-bend a chunk of pipe for $100, then I could hammer it down into the oval shape myself.

I bet Barton could bend you a piece of tube and ship it for about that...
 

Regulator

Member
Nov 20, 2011
2,496
I mounted my lights on top of the bar so that I could aim the outside lights out a bit. Worked out pretty well.
 

MrDJ

Member
Dec 4, 2011
180
Waxahachie, TX
Regulator said:
I mounted my lights on top of the bar so that I could aim the outside lights out a bit. Worked out pretty well.

Are your lights mounted to a cross bar or to a luggage rack?
 

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