USB Power Questions

Thread Starter


Joined Sep 4, 2020
New here. Please forgive my absence of knowledge in anything electrical. I do know not to use electric fences as urinal targets. . .other than that - not much.

I want to charge my phone by adding an Iphone Lightning cable to my motorcycle. I want to hard wire it to the ignition so it's fused without using adapters, cigarette plugs etc.

I have an old USB cigarette adapter plug which I opened up thinking I could just copy what was inside but it had more components than a SpaceX rocket.

If all I'm needing is to supply 5v, is there an easy schematic someone like me could use to build on? It will all be hidden so looks don't matter.

I appreciate any and all responses.

Thanks Gordon

PS Sorry for the 1st post


Joined Aug 24, 2018
Best to start with an off-the-shelf 12V to USB cigarette lighter type charger. There's potential to damage your phone if you go down the DIY route and make a mistake. If you're worried about making it compact, try taking the circuit out of an off-the-shelf unit then solder some wires on where the cigarette plug contacts are and wire it into your battery via a fuse. This will make it more compact because you won't need a plug and socket combo.


Joined Jan 15, 2015
I would just go with an off the shelf cigarette lighter or accessory plug type charger giving you 5.0 volts on a few USB connectors. That's what I use on my bike. If you want it always powered on just get a socket and wire direct to battery through a fuse. The sockets with short wire runs are common.