MrWizard wrote:
yes and NO
yes you can build one,
but according to posts on HoFo ( Howards Forums) the original OS rom, would shut the mobely off after detecting a constant 12v for a measured amount of time
after all when the engine is on and the vehicle is moving the voltage varies some what from 13+ to 14+
so home built power supplies were built with timing circuits to vary the voltage
the new version OS rom with timer shut off (never shut down) may not need this feature, but I would not dismiss the $35 power supply as a rip off
The ones shown in the link above do not have the variable voltage feature. With the updated firmware set to never shutdown, there have still been some reports of the Mobley disconnecting every couple of days using an external power supply. That's easily worked around with a cheap lamp timer that shuts it down for a short period at 3am or so. Mobley's without the latest version firmware will automatically update after activation, but it can take awhile for it to occur. The Mobley must be on for the update to happen.
I'm going to make a USB cable for mine that will work with either a 12VDC USB lighter adapter, a 120VAC USB adapter, or a USB battery pack, all items I already have on hand for other USB devices. The parts I've ordered for the cable include a USB cable with a 5VDC to 12VDC voltage booster built in to the plug and female ODB2 connector. Total cost for the two parts is $8.14.
