problem with my hella lights

[bmw325csi]

If you haven't fixed this yet, be sure to check the prong on the light bulb. When I installed these lights, I remember one of the prongs was contacting the headlight frame and causeing it to short out every time I would high beam.

[Mystikal]

As long as the bulbs are still DOT 55/60 on the H4 and 55 on the H1, I can't see why they'd need bigger fuses. Should be pulling the same amount of power.

You'd think so, but I definitely remember Hella's instructions saying to put 10A in (and it looks like at least one other person recalls that also).

[Mystikal]

The H4's were on as daylight running as well, and they seem to get too hot and end up cracking the lens - so I am in the process of switching to Euro ellipsoids (just need bulbs to arrive).

The exact same thing happened to me. I was driving in cold weather for about 3 hours with the lights on, and when I stopped I realized BOTH of them shattered. No rock impacts or anything like that, just spider cracks throughout both. They were like 7 years old at that point.

I replaced both with new units, had a shop rewire to eliminate the Canadian DRL, and threw HIDs in. No problems since.

[Sam Cogley]

Weird. I've never seen a Hella H4 light break (except for one I dropped onto a brick driveway lens-first :( ).

[gearheadE30]

I've actually heard of this before as well. I think it has something to do with heat cycling and the lense not getting as warm as the rear reflector, causing the different rates of expansion to crack the lenses. HIDs would help because they don't produce as much heat.

Have you had people flash their lights at you? Generally, HIDs in a non-projector style housing isn't a great idea.

[golde30]

as soon as i started running any aftermarket lights i had to upgrade to 10A fuses in the box. i have been running 10A in there for about 3yrs, my wires arent melted.

[deutschman]

10a's are working great.

[Mystikal]

Have you had people flash their lights at you? Generally, HIDs in a non-projector style housing isn't a great idea.

H4 HID capsules have a shield that covers half of the bulb. It looks pretty cool, only the top half of the housing lights up:



It throws out more leakage than US/Euro ellips, but it's still entirely within reason. I've never been flashed.

[cferb]

This is funny, my electrical engineering teacher was just talking about this exact scenario, replacing the fuse with a higher amp one, and how stuff's gonna catch on fire.

Sounds fine in this case, it's just funny to me.

[Sam Cogley]

This is funny, my electrical engineering teacher was just talking about this exact scenario, replacing the fuse with a higher amp one, and how stuff's gonna catch on fire.

Sounds fine in this case, it's just funny to me.

Maybe if the wiring installed was just marginally big enough for the current flowing along it. The headlight wiring in an E30 is plenty heavy to carry 20a of current instead of 15a.

BMW's obsession with 7.5a fuses is rather odd. They aren't even all that easy to find for replacement purposes.

[hendrixvodu]

i have the h4 set up and i never changed the fuses...still 7.5A ...BTW they work great! no probs with them 2 years in

[cferb]

Maybe if the wiring installed was just marginally big enough for the current flowing along it. The headlight wiring in an E30 is plenty heavy to carry 20a of current instead of 15a.

BMW's obsession with 7.5a fuses is rather odd. They aren't even all that easy to find for replacement purposes.

Yea, even if it was wiring meant for 7.5A, they always leave some room, an extra 2.5A wouldn't matter. I just thought it was humorous that he was talking about how it was dangerous, and here I am reading about someone using it as a fix.

[FredK]

This is funny, my electrical engineering teacher was just talking about this exact scenario, replacing the fuse with a higher amp one, and how stuff's gonna catch on fire.

Sounds fine in this case, it's just funny to me.

Yes. That's true, if you just increase fuse size without calculating anything, you'll run into problems.

If you are installing Hella H4/H1 in the place of stock sealed beams, you need to increase Fuses 1 and 2 to 10A. It has to do with the power switching arrangement. In a sealed beam car, the low beam has two filaments. On low, Fuse 13/14 supply the power. When you flick the highs on, it lights both the high beam AND the second filament in the sealed beam through Fuses 1 and 2.

When you have a 55W/60W H4 bulb and 55W H1 bulb lit, you have a demand of 115W on Fuse 1 and Fuse 2.

P=IV and if P=115W, V=12V, then I=9.6A. So you need a fuse with a rating of >9.6A. That is why you need a 10A fuse.

[Farbin Kaiber]

Yes. That's true, if you just increase fuse size without calculating anything, you'll run into problems.

If you are installing Hella H4/H1 in the place of stock sealed beams, you need to increase Fuses 1 and 2 to 10A. It has to do with the power switching arrangement. In a sealed beam car, the low beam has two filaments. On low, Fuse 13/14 supply the power. When you flick the highs on, it lights both the high beam AND the second filament in the sealed beam through Fuses 1 and 2.

When you have a 55W/60W H4 bulb and 55W H1 bulb lit, you have a demand of 115W on Fuse 1 and Fuse 2.

P=IV and if P=115W, V=12V, then I=9.6A. So you need a fuse with a rating of >9.6A. That is why you need a 10A fuse.

Posts like that are why I <3 Fred.

[Sam Cogley]

Yes. That's true, if you just increase fuse size without calculating anything, you'll run into problems.

If you are installing Hella H4/H1 in the place of stock sealed beams, you need to increase Fuses 1 and 2 to 10A. It has to do with the power switching arrangement. In a sealed beam car, the low beam has two filaments. On low, Fuse 13/14 supply the power. When you flick the highs on, it lights both the high beam AND the second filament in the sealed beam through Fuses 1 and 2.

When you have a 55W/60W H4 bulb and 55W H1 bulb lit, you have a demand of 115W on Fuse 1 and Fuse 2.

P=IV and if P=115W, V=12V, then I=9.6A. So you need a fuse with a rating of >9.6A. That is why you need a 10A fuse.

There's a slight problem: the H4/H1 bulbs and the stock sealed beams should have the same wattage rating on the same switching arrangement. It doesn't make any sense that the H4/H1 setup would blow fuses that way.