What size fuse??

younger06

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I have a set of SW Motech Hawk foglights/spotlights on my 07 GSA (the old halogen type not the newer LED ones) the fuse holder with the fuse in it at the battery end of the loom kinda burned out/ melted.........I'm gonna buy an inline fuse holder to repair this.......what amp fuse should I use ???


https://www.adventurebikewarehouse.com/Hawk-Fog-Light-Set-BMW
 
According to the link they are 55 watts each x2=110 divide by 12 voltage would give 10 amp fuse. The question I’d be asking is why is it burned out? I wouldn’t just bang in a new holder and fuse. JJH
 
According to the link they are 55 watts each x2=110 divide by 12 voltage would give 10 amp fuse. The question I’d be asking is why is it burned out? I wouldn’t just bang in a new holder and fuse. JJH
That’s a 9.2Amp load. Assuming a bit of in-rush current when the lamps are cold, and a bit of variability in fuses, I would suggest 10A fuse might be a bit low. Suggest 15A would be a better fit.
 
Your probably right. But if there was a fuse of too high a rating might that be a reason why it didn’t blow soon enough? Remember 12 volts is really 14 when the engine is running. Anyway as I say I’d be investigating and trouble shooting before banging in a new holder fuse. JJH
 
You can make one yourself. Two female insulated terminals and a fuse. Temporary fix of course. JJH

I appreciate the help JJH.......but, I'm dufus when it comes to electrics. I don't understand what you have suggested.

I wanted to just purchase what I need and hand the lot to someone who knows what they are doing.
 
I may end up buying new lights...........the lamp units themselves are probably past their best.
 
I may end up buying new lights...........the lamp units themselves are probably past their best.

No! It could be a frayed wire. Buying new lights won’t cure that. I’m not an expert but I can do a bit of poking around. Bring it over to me. I have a multi meter. Never used it before..... joking. JJH
 
The fuse is not the problem, although it caused the problem...

If the spots are 110 Watts in total, that's about 9 amps through the switch, connectors & wiring. If the wiring is thin (e.g. 0.5 sq mm), it'll get warm and drop volts at that current. The fuse should be rated to protect the wiring - it should blow before the wiring melts.

The other possible problem is a dirty/corroded (high resistance) connection, which will drop volts and generate enough heat to melt plastic. Typically a switch, plug/socket, bullet, spade or Lucar connector, or...

...a fuseholder!

Best bet is to clean or replace any dodgy switches, connectors and fuseholders, then re-wire your spots through a relay, using the minimum length of thick cable, straight to the battery via a 15 or 20A fuse, then actuate the relay from the existing switch circuit. That way, the old, dodgy switch circuit only has to handle a fraction of an amp to power the relay and the high current goes through the new, heavy-duty cable and relay.

Bonus - your spots will be brighter, because less power is wasted warming up the wiring loom. :D

Cable specs here: LINKY
 
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No! It could be a frayed wire. Buying new lights won’t cure that. I’m not an expert but I can do a bit of poking around. Bring it over to me. I have a multi meter. Never used it before..... joking. JJH

Thanks for the offer.

My bike is in Platinum for an unrelated issue.......and a possible failing battery (which could be related)......there is a nice big powerful Motobatt going into it.
 
Thanks for the offer.

My bike is in Platinum for an unrelated issue.......and a possible failing battery (which could be related)......there is a nice big powerful Motobatt going into it.

It’s in much safer hands than mine. JJH
 
All the better to set fire to your wiring loom. :D

Pure optimism.......I love it!!
I've a 38ah car battery in the Guzzi! :eek: :(

At some point i'm going to have to face the ordeal of "addressing the issue" :rolleyes: of 30 year old wiring and connections etc.
But where do i stop? Or start for that matter! I see no point in just throwing out the old and putting in new when it's a total PITA to do and from what i've seen of other 'restorations' not always needed. The recent time lapse video of a Honda 750/4 on here - i swear a lot of the wiring and connectors put into the restored Bike appear to be the original in that. :confused:

~~~
Younger06 - i'm equally dufus / electrophobic. :thumb2 :beerjug:
 
I've a 38ah car battery in the Guzzi! :eek: :(

At some point i'm going to have to face the ordeal of "addressing the issue" :rolleyes: of 30 year old wiring and connections etc.
But where do i stop? Or start for that matter! I see no point in just throwing out the old and putting in new when it's a total PITA to do and from what i've seen of other 'restorations' not always needed. The recent time lapse video of a Honda 750/4 on here - i swear a lot of the wiring and connectors put into the restored Bike appear to be the original in that. :confused:

~~~
Younger06 - i'm equally dufus / electrophobic. :thumb2 :beerjug:

Didn't mean to panic anyone. :blast

On any old bike, connectors can corrode, switches and relays wear out, wiring can chafe or get trapped (the latter happened to my R1150GS recently). Also POs may have made less-than-adequate additions and modifications. On my old GS, the loom wrapping has deteriorated and is falling apart in places, I've replaced a couple of relays, cleaned some salt-corroded connectors and dismantled and cleaned the brake-light switch.

I wouldn't go as far as suggesting replacing wiring looms on a maintenance basis, but unplugging, cleaning and greasing (silicone grease, Vaseline or ACF50) connectors every so often. In addition, any electrical symptom (intermittent operation, flickering lights, frying or sizzling noises, blown fuses, melted wiring or components, smoke etc.) should be investigated beyond replacing a blown fuse or a squirt of contact cleaner.

Not all circuits are fused and sometimes those that are will have the wrong fuse fitted (10 amp kept blowing, so I put a 20 amp in...) which means that a fault could melt the wiring, which in turn could melt and short-circuit neighboring wires in the loom. Many folks have an irrational fear of electrics, or misplaced confidence, so they may ignore problems or make ill-advised repairs such as bypassing the faulty circuit with a wire straight to the battery.

All I'm really saying is that replacing a fuse without fixing the fault which caused it, or installing equipment and wiring without understanding how many amps make five* is asking for trouble.





* two amps, two half-amps, an amp and a half and half an amp. :D My old dad taught me that when I was a nipper.
 
Didn't mean to panic anyone. :blast ...
Ah no bother - i do a good job of panicking all by myself. :rolleyes: :D
Ta for the post - it all makes good sense and backs up what i think myself is practical. :thumb2
.... just even though i know all is as good as i can get it on the Guzzi - there never seems to be quite enough electricity to go around. :mad:
 


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