Tuesday, 2 February 2016

Mobile USB power

I have a dashcam DVR. Its mounted, as the law requires, behind the rear view mirror, at the passenger side, and not impinging on the area swept by the wipers too far. Its set to start recording automatically as soon as its powered, which up until today was when I pushed the USB adapter into the fag lighter socket. This arrangement is far from ideal, not least because the power cable just hangs about loose.

So today, I installed a 12v to 5v 3A USB power converter, using a clever little gizmo that allows you to add an extra fused connection into the vehicle fusebox by replacing a fuse with this device. I chose to pinch a connection from the front windscreen wiper supply, which I knew was an ignition switched circuit. This is a 20A mini blade fuse. So, pulling that fuse and installing it instead in the lower socket of the 'Add-a-circuit' fuseholder, a 5A mini blade fuse in the upper socket, and plugging the whole assembly into the original fuses place in the fusebox, and I had a 5A switched 12v supply.

The microUSB power cable to the cam was fed up and under the headliner behind the courtesy light, across to the passenger side door pillar, down inside the trim, and behind the glove box - which happens to be where the fusebox is. The DC converter blocks +ve wire was crimped to the new fuse units output wire, and the -ve, fitted with an eyelet crimp, bolted to the chassis metalwork.

Now, this power block came with a standard USB socket as its output connection. So, a section of the outer jacket of the cable was removed, exposing the two wire cores, to which the USB lead for the cam, now cut and with the cores bared back, was attached using two 'snap-in' insulation displacement connectors. I was a bit dubious that these would work with such thin wire, but on powering up all is well. The camera starts up when I start the ignition, and shuts down when I kill the engine.

The original USB connector - well, using a Stanley knife I cut out a slot in the plastic of the fascia between the glovebox and the central column of the dash, and now have a switched 5v USB port for charging my phone or Kindle!

Following on from yesterdays work on the Clansman LiPo battery, all that remains is to mark it up in such a way as to make it obvious its not a standard battery and must not be charged on a normal charger.

So, here it is swathed in masking tape ready for spraying. Whilst purchasing the automotive parts for the job discussed above, I also picked up a can of scarlet red spray paint. The top cover of the battery is going to be sprayed red, along with a one inch wide stripe right the way around the battery case.

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