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Post by johnbirchjar » Thu Mar 08, 2018 11:33 am

Hi guys,S'me again,(just for a change)When the Classic ran with the air cooled engine the Ign; fuse was 10amp,now I have the Commander engine with Rad;Fan,Water Pump,AND Twin H/Lights.The 10 amp fuse blew,(as did the upgraded to 15 amp,)I have now gone to 20amp smiley,How can I calculate how big a fuse is required?(allways assuming the cause of the blown fuses is 'cos of the extra 'leclic's wink)J.B.

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Joined: Thu Jan 12, 2017 1:32 am

Re: Fuses

Post by BlackIP2 » Thu Mar 08, 2018 6:57 pm

I would wire in a separate fuse for the lights, at the very least.
As for calculating the fuse amp sizes, assuming you know how many watts each item is rated at, you can calculate the amps by the formula: watts = amps x volts. So a 60 watt headlamp uses 5 amps (5 x 12 volts = 60). However, you may need to go up to the next size fuse otherwise it might blow all the time. For a twin 60w light you might have to fit a 15 amp fuse.
This is only my humble opinion. Those with more extensive electrical knowledge may offer further advice.

Mick Taylor
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Joined: Mon Aug 11, 2008 8:59 pm
Location: Ivychurch, Kent

Re: Fuses

Post by Mick Taylor » Thu Mar 08, 2018 9:14 pm

Hi John, I am pretty hopeless with electrics, particularly fault finding, however, having had the need to fit some accessories to a bike with a Canbus system (which meant nothing to me) I came across this little gadget.

In essence, you simply wire this to the battery and one wire to a switched live (only becomes live with the ignition on).....from there, you have the option to run up to six fused circuits each with the option of being permanently live or switched live, so you could run everything you want independently of each other.....which has the added benefit of making fault finding easier.

It's very simple indeed; I understood what I was doing when I read the instructions, so it must be......I have used one on a BMW and another on a Kawasaki.....all you need is a space to put this fag packet sized box of tricks.....have a read of the description.

https://www.nippynormans.com/f650stf650 ... fuse-panel


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