Ignition switch minimum electrical requirements

[MadeThatMyself]

I'm curious if anyone knows the minimum specs needed for an on/off ignition switch, specifically amp requirements? I bought an ignition switch from TC bros, but it's a little bulky. I'm wondering if I can find a mini key switch that might be easier to hide. PO had a toggle switch mounted between the carburetors in the middle of the bracket.

I have a 1981 xs650 heritage special running a battery with OEM CDI ignition. Bike has been completely stripped down and I will be wiring from scratch. Thanks.

 

[TwoManyXS1Bs]

I'd call 15a as a minimum.
I use a mini DPDT toggle, rated 15a, with both banks wired in parallel, kinda doubles the rating...

 

[Jim]

I'm curious if anyone knows the minimum specs needed for an on/off ignition switch, specifically amp requirements?

Don't have an answer for you, just sumpin' for you to ponder while picking a switch. In aircraft mechanics school we used to teach "switch de-rating."
For example, if you had an engine that redlined at 10,000 rpm.... and you ran it at 10,000 rpm all the time, it wouldn't last very long, would it.... Same with a switch that's rated at, say... 10 amps. If you pump 10 amp through it all the time, it ain't gonna last.... For longevity... as a rule of thumb, use a switch that's rated for at least 25% more than the load it's expected to carry.

 

[MadeThatMyself]

Electrical is definitely not my strongest knowledge base. I stumbled onto the post below from pamcopete:

http://www.xs650.com/forum/showpost.php?p=21821&postcount=5

Based on what he has listed in terms of amp draw, it sounds like my LED lighting may help reduce my requirements.

My math based on his list:
ignition coil- 1.6 amps
regulator- 2.9 amps
reserve to charge battery- 2 amps
headlight (40 W/14.5 V)- 2.8 amps
LED Tail/Brake/Turn signals- Estimated total 0.5 amps max
DCC mini gauges- LED backlight and indicator lights- Estimated 0.2 amp max
------------------------------------------------------------------------
Total = 10.0 amps max

Does that sound right? Is there anything I am missing? If this looks plausible then I should be safe with 15A switch.

 

[Jim]

reserve to charge battery- 2 amps

You can scratch that..... power back to the battery is un-switched. It's a direct line between the reg. and batt. Other than that, looks pretty close.

 

[XSLeo]

Most of these bikes came from the factory with a 20 amp main fuse. Shouldn't your main switch carry at least this amount?
Wouldn't want the switch to burn before the fuse.
I might go with a 25 amp rating.
You could use a lighting relay, they are rated somewhere around 35 amps. Some of the 5 prong relays are rated up to 80 amps.
Wire it in to carry the main load of the bike. Then most any small switch to turn the relay on/off.
I have one on my 75 to power the ignition. the kill switch only has to carry enough current to trip the relay. This set up reduces the line losses for power to run through all the connections up to kill switch and back down to ignition.
Leo