20a headlight fuse = certain bike death?

[Brettus]

Sorry for the sensationalism in the headline but my query got a bit lost in my last thread and would like some idea on this so I can sleep tonight knowing what I have to do rather than just a few guesses, being as I could do with getting my lights working before I have to ride home tomorrow evening.

I put twin 55w HIDs in and it blew the stock 15a fuses, but with just the single one in it didn't, so I suspect it isn't too far over the limit.

Can I, or has anyone else, put a bigger fuse in the headlights without any ill effects? or is it really risky? I kinda trust the oem loom more than anything I'd put together so would prefer to keep it as that but if 15a is pushing the loom already and people have had problems then fair enough I'll have to do it properly.

[Ruffy]

IMHO, not certain death.

2 x 55W is just over 9A continuous at 12V, so the 15A should be fine in theory. However, many auto fuses quoted rating are actually not full continuous rating, so that could be the problem.

How long does it take for the fuse to blow? Is it related to engine speed, as, pessimistically, this could indicate a reg/rec issue.

Have you put a meter on to see what current it's actually pulling?

[punyXpress]

Doesn't the HID draw more current than stated at the 'warming-up' stage?
Reckon TLW's earlier reply says it all, but then I know nothing about electics - I come from ...

[the_lone_wolf]

great theory, except the HID kit draws a significantly higher current when you first turn them on in order to strike the arc and then stabilise it, it's then that they blow the fuse, once settled down mine use less juice than the halogen lights

[Brettus]

it blows after 5-6 seconds after starting, 2-3 after flicking high beams on.
didn't get to revving it but should that be a problem already with an 11k K6?
Thanks for the reply

[Ruffy]

Originally Posted by the_lone_wolf

great theory, except the HID kit draws a significantly higher current when you first turn them on in order to strike the arc and then stabilise it, it's then that they blow the fuse, once settled down mine use less juice than the halogen lights

Originally Posted by Brettus

it blows after 5-6 seconds after starting, 2-3 after flicking high beams on.
didn't get to revving it but should that be a problem already with an 11k K6?
Thanks for the reply

Sorry, I don't have specific knowledge of auto HID, so I'm having to relate from other situations I do know about. I should have properly engaged my brain and realised that it's the effect of the ballast and switchgear causing a startup peak. Also, from info in the other posts, i'm now confident that you can disregard my worry over reg/rec. Phew!!!

If the duration of the startup current peak is short and the current level is not too high, say 10-15 secs at 2-3 x continuous rating max, then I believe there shouldn't be an issue with using the standard loom and higher rated fuse, especially if, as TLF says, the steady state current is lower than stock lights. But (stating the obvious) the higher fuse rating will give less protection in the event of a real fault, leading to greater risk of wiring damage. I'm also assuming you're not starting and stopping 'em like a fairground ride!

Personally, I would experiment by putting a higher fuse in and metering current flows, just to double check. Unless anyone has got some real-world figures for startup peak current, startup duration, steady state current?

[the_lone_wolf]

Originally Posted by Ruffy

If the duration of the startup current peak is short and the current level is not too high, say 10-15 secs at 2-3 x continuous rating max, then I believe there shouldn't be an issue with using the standard loom and higher rated fuse, especially if, as TLF says, the steady state current is lower than stock lights. But (stating the obvious) the higher fuse rating will give less protection in the event of a real fault, leading to greater risk of wiring damage. I'm also assuming you're not starting and stopping 'em like a fairground ride!

startup current draw can be around 13A for each ballast so 26A in total and lasts a few seconds

tbh for the sake of 30 minutes with a set of wire cutters and a soldering iron it's foolish not to do it properly...

you need anti-surge fuses by the sound of it. If the HID draw current to start up then anti-surge will give the inital protection.

[Ruffy]

Just done a quick check of my haynes manual and found and also scanned through Brettus' original thread.

According to the (SK5) wiring diagram there's no relay in the headlight circuit. Another budget move by Suzuki leading to another poor assumption by Ruffy!

So I need to change my best advice to suggest fitting at least one relay, along with a separate, high power feed & fuse from the battery in the main light circuit as per TLW's advice in the original thread. It's not so much the wiring loom I worry about as the switchgear - it's frustrating having a light switch suddenly set fire and partially melt by your throttle hand (yes it did happen to me once!)

Doesn't the high beam on HIDs work by moving a small cover? If so, then the high beam wiring's possibly man enough not to need another relay, but this all depends on how the HIDs internal wiring works, so, overall, probably better to play safe and go with TLW's earlier advice in full.

Hope I haven't confused things too much.

I recently had the same problem when I fitted twin 35w HIDs. It worked fine with one but not with two (cos one supply wire supplies both lamps). When I tested the lights on a power supply on the bench each lamp drew 8.5amp on start up and 6.5amp after 5 - 10 secs when warmed up. I thought it would be OK to up the fuses to 20amp and they didn't blow but the lights would both flicker and eventually one would go out. The wiring used on the bike got warm to the touch as its just not thick enough to supply the amount of current needed to supply both lights. I installed seperate thicker gauge wiring from the battery to a relay via a fuse. A bit of grief in the end but the lights are amazing so well worth the effort.

I have H4-4 HIDs so they have 2 xenons in each bulb for main and dipped so 4 ballasts in all. If you have a H4-3 then you have 1 xenon in each bulb and a solenoid moves the xenon to the main beam position from the dipped. These defo need a relay as a the solenoid will draw quite a bit.