off road lights

[Tul01]

My brother in law has a set of heavy duty halogen lights wired in by someone else. They started blowing fuses in the rain then all the time. I helped him rewire, solder and shrink wrap all the connections. Turn them on and there was light. For about 10 seconds until it blew the 20 amp fuse BIL doesn't remember what the original fuse was. It seems to me that the fuse should either be larger or it is wired in wrong. There is a 40 amp relay in the system. It is wired relay, black and white to switch, relay one red (fused )to the battery terminal and relay one red to the lights. The lights are grounded to the frame. I always thought the purpose of the relay was to take the brunt of the power from the battery to the lights so you don't burn up fuses. Should I have put a 40amp fuse in?

 

[kebo]

Really, as much current as those lights are drawing, you should run a separate circuit with properly sized wiring and fuse straight from the battery to protect the lights and wiring. Not to mention possibly preventing an electrical fire. You didn't say what they are installed on, but honestly, those lights may just be a bit too much.....

 

[doall]

I have 100 watt Hella's on my truck, I don't think any of the fuses would handle them so they are just on a toggle in the dash straight from the battery. No problem, just don't leave them on without the truck running.

 

[aczlan]

I have 100 watt Hella's on my truck, I don't think any of the fuses would handle them so they are just on a toggle in the dash straight from the battery. No problem, just don't leave them on without the truck running.

100W at 12 volts is only 8.3 amps/light. A 40amp relay and a 40amp fuse (with the correct wire) would handle 4-5 lights no problem (and leave you with a smaller wire and a lighter switch in the cab.
You should at very least put a fuse within 6" of the battery. It would be a shame if the wire wears through, shorts, overheats and burns down your truck just for the lack of $7 worth of fuses and a fuseblock.

Socket: Amazon.com: 12 VDC 5-PIN RELAY SOCKET: Electronics
Relay: Amazon.com: 12 VDC Waterproof Relay SPDT 30/40A with Metal…
Fuse Block: Amazon.com: In-line ACT Water-resistant Fuse Holder - 10 AWG:…

Aaron Z

 

[Willl]

Should I have put a 40amp fuse in?

How much are these lights drawing ?

Edit; And what size wire you running ?

 

[doall]

100W at 12 volts is only 8.3 amps/light. A 40amp relay and a 40amp fuse (with the correct wire) would handle 4-5 lights no problem (and leave you with a smaller wire and a lighter switch in the cab.
You should at very least put a fuse within 6" of the battery. It would be a shame if the wire wears through, shorts, overheats and burns down your truck just for the lack of $7 worth of fuses and a fuseblock.

Socket: Amazon.com: 12 VDC 5-PIN RELAY SOCKET: Electronics
Relay: Amazon.com: 12 VDC Waterproof Relay SPDT 30/40A with Metal?/url]
Fuse Block: [url=http://www.amazon.com/line-ACT-Water-resistant-Fuse-Holder/dp/B0002KR88A]Amazon.com: In-line ACT Water-resistant Fuse Holder - 10 AWG:?/url]

.

Aaron Z

I did put an inline fuse in. Sorry about the lack of info. But thanks for looking out for little ole me. Just an idea for him

 

[doall]

like your sig. line Aaron Z.

 

[aczlan]

like your sig. line Aaron Z.

Thanks.

Aaron Z

 

[Willl]

like your sig. line Aaron Z.

Sure beats all the 'book' phrases hands down.

 

[doall]

definately made me think about all the somewhat uneducated responses I have posted. I'll do better. Now if I could just think up one of my own.
I really don't claim to know a lot about electronics but I can usually handle simple things.

 

[arrabil]

10 seconds until the fuse blew means something is wired wrong. If its wired right and blows the fuse (due to overload) it will blow it instantly. I wonder if there is still a bad connection but a really fat wire in the loop absorbing the current overload. Do any of the wires feel hot? Any of them much bigger than the others? Could be a loose short that needs to be wiggled to make contact.

I would start from scratch....

 

[Willl]

still a bad connection

I'm thinking same.

 

[kebo]

100W at 12 volts is only 8.3 amps/light. A 40amp relay and a 40amp fuse (with the correct wire) would handle 4-5 lights no problem (and leave you with a smaller wire and a lighter switch in the cab.
You should at very least put a fuse within 6" of the battery. It would be a shame if the wire wears through, shorts, overheats and burns down your truck just for the lack of $7 worth of fuses and a fuseblock.

Socket: Amazon.com: 12 VDC 5-PIN RELAY SOCKET: Electronics
Relay: Amazon.com: 12 VDC Waterproof Relay SPDT 30/40A with Metal?/url]
Fuse Block: [url=http://www.amazon.com/line-ACT-Water-resistant-Fuse-Holder/dp/B0002KR88A]Amazon.com: In-line ACT Water-resistant Fuse Holder - 10 AWG:?/url]

Aaron Z

Your thinking is correct, but you left out the inrush current factor. If all 4-5 lights come on simultaneously the initial current draw will probably be over the 40 amp fuse rating. Depending on what type of fuse (slo-blo, fast-blo, time delay, etc) it may or may not blow the fuse. Thats why in electricity/electronics you typically over design for this sort of thing and leave yourself a comfortable margin. The end result is the protection device (fuse) should be the weakest link, and the first thing to go.

 

[Tul01]

Thanks for the quick responses guys, the fuse is within 6" of the battery, I will look at the switch end next. I didn't notice anything getting hot when I was over helping. The new wires at the light end are 14g, maybe I will have a closer look at the wiring running to the switch, I knew the wiring was bad to the lights as it fell apart and I could see corrosion so I just assumed that was the problem. thanks again
Brent