Sealed high beam popping fuse

[15Michaeljoseph]

Alright, well, after some research and head scratching I decided to ask for advice about this very novice problem, because I'm really not an electronics guy.
Car's an 87 325is, and I did the hella H4 low beam conversion, keeping the 55w high beams, stock sealed, because they're more than bright enough. Now sometimes the drivers side high beam pops it's fuse. It only happens sometimes and only on the driver's side, that's what confuses me, but it seems to be happening more and more frequently. It's hard to describe but basically it seems like it's a delayed fuse popping. I mean if I'm going down a dark road with the highs on, it takes a couple of minutes before the fuse blows. everything seems to be working as it should... there are no breaks in the wiring from the bulb to the fusebox, not even a tear in the insulation. I've tried cleaning the bulb plugs and contacts, to no avail. I read online that people running this setup can switch the fuse from a 7.5 to a 10, but the car was designed for 7.5 so i don't think that's a good fix.
What do I do? could it be an issue with the bulb? the driver's side bulb is a wagner and the passenger side is a sylvannia if that might make any difference... help!




--Mike

[dsphil]

I think here is your problem, but I am not an electrical expert. Hella conversion use 2 filament h4 60/55w bulb. 60w for the high. Sealed high beam is 55w. When you turn on your high beam, both the sealed beam and the 60w h4 bulb is turned on. That adds up to 115watts. 115w/12.9v = 8.9amps. Your fuse is 7.5amp. Perhaps someone chime in.

[Stanley Rockafella]

nope that's correct.

Many moons ago when I had my 86 325es I did a headlight conversion (back in 2002) to some goofy Chinese brand of headlamp conversions. After that, whenever I'd turn on the high beams I'd blow the fuse. Sure enough, upgrading to the 10A was all it took to keep the system running smoothly.

Go ahead OP, I'm certain you'll be alright

[15Michaeljoseph]

Sealed high beam popping fuse

okay guys I trust this forum. I know upgrading fuses is almost always dangerous and just plain bad practice, but I feel better knowing it is alright in this case.... I also I read somewhere that the wiring is rated higher than needed as well, so I suppose I'm fine. I'm going to drop in two 10 amp's and drop a line back.... Maybe I'll stop at napa and pick up two new 55w highs just so everything's fresh.
damn these sealed high's are super bright compared to e36 or even e53 X5! Impressive!


--Mike

[15Michaeljoseph]

Sealed high beam popping fuse

Update:
10A fuse is a safe upgrade to fix the issue. as it turns out BMW overkilled on the wiring, using something like a 16 ga wire. with that in mind, theoretically you could use 100w bulbs safely because the wiring is good for something like 130 watts and up to around a 15A load. So it's safe to say that this 10A fuse upgrade is okay to do. Now my high beams can stay on when drive down a wooded road.

now for some 100w aircraft landing lights ;b


--Mike