All this is on my 2007 DL1000, if it matters.
I have a 12V socket on the handlebars, wired in what seems to me an odd fashion: instead of connecting to the nice aftermarket fuse block (seen below):
...the socket's wires terminate in an SAE plug, just like the plug people usually wire directly to the battery for a battery tender. So I have a pair of these SAE plugs back near the battery, like this:
To clarify: one SAE plug goes to the battery and came with a 7.5A fuse in-line on the positive side. The other SAE plug goes directly to the 12V socket, and has no fuse in-line. But, it is protected by the 7.5A fuse when powered, since it goes through the battery tender connection.
If I connect the 12V socket to the battery tender plug, I have power at the 12V socket when the bike is on (either key in "on" or engine running). I can run a 12V tire inflator off the 12V socket, no problem. Specifically, I have this Sears Craftsman inflator, which I originally bought to use with my car:
That's great, but I also want to be able to charge my phone when I'm out.
So far, I can't. Every time I plug a USB car charger into the 12V socket, it not only won't charge, it no longer works at all! I've now been through 2 of them. WTF is going on here?
One of the chargers says it can take a maximum input of 4.2A at either 24V or 12V. The other doesn't give an input current, only a voltage (again, 24V or 12V). Both chargers are dead as can be, after I tried to use them with the 12V socket on my bike.
Is the 12V socket somehow frying the USB chargers with too much current? How is that possible? I don't see why the chargers would draw more current than they can handle, otherwise they'd fry immediately - or else pop a fuse - when I used them in the car. I don't have to worry about the maximum current rating when I'm using the USB chargers in my car, so why would it be any different on the bike?
FWIW, the circuit supplying the 12V socket in the car has a 20A fuse. So if the USB chargers are somehow "dumb" and will draw more current than they can handle, you'd think they'd fry themselves in the car, too.
Is there such a thing as a special motorcycle-only, 12V USB charger? I thought the motorcycle's power system wasn't that different from the car's, but maybe I'm missing something.