Many car stereos/radios don't really turn off. They mute and the front
panel goes dark, the power amp sections shut down, and the controls go
to sleep, but they are still partially on and drawing current. I guess
the manufacturers assume that you drive your car frequently.

The current draw is through the main power wire, the other wire,
frequently connected to the ignition switch, doesn't draw much current
at all -- it is used to signal the unit to wake up.

I had to search high and low to find a unit that actually powers off --
not only from the front panel power button, but from the remote, too. So
I could turn off the music when I get into bed rather than have to lean
up to the dash to shut things down.

--
Jack "Rocket j Squirrel" Elliott
1984 Westfalia, auto trans,
Bend, Ore.

On 09/01/2015 06:08 AM, Jim Felder wrote:
> About a month ago I wrote about having installed two pairs of USB ports and
> an LED voltage display in my Vanagon. The round double outlet on the dash
> took the place of my factory Eberspacher heater knob and the
> outlet-and-voltmeter combination set neatly into what was the rear ashtray.
>
> That's when I noticed a drop in voltage that would flatten the battery
> after a couple of days of being parked. Long story made very short, I
> discovered that it was my radio in standby mode that was draining the
> battery. I pulled the fuse to the radio on Saturday and this morning the
> voltage is showing 12.9, exactly where it was when I pulled the fuse.
>
> The reason that this was unknown to me all this time is that coincident
> with the addition of the USB ports the Vanagon was, except for use of my
> wife's Prius, my daily driver had been the Vanagon. When I got a TDI Jetta
> the Vanagon started sitting for days or a week at a time, and that's when
> the problem showed up.
>
> I could wire the radio to the switched 12v circuit that no doubt came with
> it, but then I would have to have the key on to listen to music while
> camping. Is anyone using a switch on the circuit, and if so how was it done
> and how does it work out for you?
>
> Jim
>