What size fuse for headlights? Fusible link?
Discussion
I'm wiring my home-build up and have connected the headlights. I have a 25 amp in-line fuse in the light supply circuit, but it gets hot with the lights on for ten minutes. The switch was also getting a little warm too, but nothing you can't put your hand on. It is not melting down, just seems a little odd. The wiring all feels cool.
Decent switches are not the most available animal where I live, the Philippines, so I changed things over and put a relay in both hi and lo beam circuits to take the load off the main headlight switch and the dip switch. Now they are cool.
However, the fuse housing still gets a bit warm with the lights on, as it obviously has the same load on.
Similar to this:
The rest of the system is protected by a six slot blade fuse holder, but the headlights are doing my head in.
What size fuse normally goes in the headlights? They are just halogen sealed beams, nothing fancy.
I have read on the web about 'fusible links' in the high load circuits? Are these home made, or bought?
Decent switches are not the most available animal where I live, the Philippines, so I changed things over and put a relay in both hi and lo beam circuits to take the load off the main headlight switch and the dip switch. Now they are cool.
However, the fuse housing still gets a bit warm with the lights on, as it obviously has the same load on.
Similar to this:
The rest of the system is protected by a six slot blade fuse holder, but the headlights are doing my head in.
What size fuse normally goes in the headlights? They are just halogen sealed beams, nothing fancy.
I have read on the web about 'fusible links' in the high load circuits? Are these home made, or bought?
A pair of 65W main beam bulbs are only going to draw 10 or 11A from a nominal 12V, so a 25A fuse sounds fine....but I suspect the problem is more that the fuseholder itself isn't great quality and is suffering poor contact resistance, which is causing it to heat up.
Simplest and probably best solution is to split the fusing up a bit - have 4 rather than 1 fuse, one each for left & right dip & main circuits. A 10A fuse for each will be fine - plenty big enough to avoid nuisance failures but small enough to protect the wiring.
Simplest and probably best solution is to split the fusing up a bit - have 4 rather than 1 fuse, one each for left & right dip & main circuits. A 10A fuse for each will be fine - plenty big enough to avoid nuisance failures but small enough to protect the wiring.
I think that is the real problem: low quality fuse holder.
I was going to put a separate fuse for hi and lo, but only one is on at any time, so it makes no difference.
The wiring is a single line down to the front of the car, where it splits into two for each light, so can't really be fused individually for each side.
Maybe I can source a better quality fuse holder.
I was going to put a separate fuse for hi and lo, but only one is on at any time, so it makes no difference.
The wiring is a single line down to the front of the car, where it splits into two for each light, so can't really be fused individually for each side.
Maybe I can source a better quality fuse holder.
I went to Singapore for the weekend and hoped to find some fused relays there, but never had chance.
Anyway, I found some nice in-line blade type fuse holders in a local accessories shop, fuse was a really tight fit in the grips, so I wired one in, and left the headlights on main beam for half an hour.
Measured with my infra red heat gun, fuse/holder temp went to about 34C, which is 6 above ambient room temp (28C). The relay itself actually got a couple of degrees hotter, about 38, but nothing as hot as the old style fuse holder was getting. That was over 55c when i checked, almost too hot to put your hand on.
So, success.
Anyway, I found some nice in-line blade type fuse holders in a local accessories shop, fuse was a really tight fit in the grips, so I wired one in, and left the headlights on main beam for half an hour.
Measured with my infra red heat gun, fuse/holder temp went to about 34C, which is 6 above ambient room temp (28C). The relay itself actually got a couple of degrees hotter, about 38, but nothing as hot as the old style fuse holder was getting. That was over 55c when i checked, almost too hot to put your hand on.
So, success.
Gassing Station | Kit Cars | Top of Page | What's New | My Stuff