USB charging pont

[ThreadKiller]

Hi... fitted a usb charging point, but want to feed it from a switched positive. I have read about splicing it into tail light feed. Can’t imagine that additional load from lphone charging current will cause any problems. Any experience/ recommendations on this? Thanks.

[UnluckyTimmeh]

Depending on the bike, be very careful splicing.
If it’s a newer bike it may have can-bus which will measure resistance. If it sees an extra draw on a feed of power it’s not expecting the control module can just turn it off. I saw quite a few BMWs suffer this while working at a dealer.

What bike is it and what age?

Worst case you may be able to rig up a compact relay type system.

[ThreadKiller]

Hmm... thanks for the heads up on that. 2017 gsxs750, which i think has can bus.

[Krikkit]

If you're worried about current draw/canbus you could use a relay - the tail light switches the live without any draw, then you can wire the USB straight to the battery

[ThreadKiller]

I’ve also read about relays spiking can bus systems. Quick google suggests at 12v relay draws about 30mA and Iphone about 400mA. Relay must be the “proper” solution.... will look into it.

[bsidethecside]

May be worth seeing what official accessories are available that draw power and look for fitting instructions on tinterweb. That will show if there are any available accessory circuits that would be suitable for a load. There could be something for GPS / heated grips etc...

[talksthetorque]

I thought about this, but then I fitted a simple inline switch on the positive feed and took the power straight from the battery ( the kit I bought had the cabling with an inline fuse) I can charge my phone when I stop for a bacon butty.

[ThreadKiller]

I ended up fitting a diode protected relay. No adverse can bus related effects, and everything work... for now at least!