Neil,

My Pioneer non-cd stereo has maintenance power from some constant 12v source on the fuse box.  The actual power to make noise is switched through the key buzzer circuit.  Key in = tunes. Key out = no tunes. It takes it about three weeks without driving for the maintenance circuit to drop the battery to where it won’t start.

Jim

> On Dec 16, 2017, at 1:21 PM, Neil N <musomuso@GMAIL.COM> wrote:
> 
> Hi folks.
> 
> Caveats: my stereo/amp "maintenance" and main positive (power) wires are
> connected to the same source; even if ignition switch is off, I can turn
> stereo on. Different brands will yield different results. Maybe some
> stereos turn the USB device off when stereo turned off ? My stereo does not
> have a USB port on front panel. It uses a USB cable.
> 
> My Alpine NON CD head unit + amplifier "maintenance" current draw when
> turned off. Measurements are rounded up/down. I inserted/removed thumb
> drive several times while measuring:
> 
> - music USB thumb drive inserted:      0.210 mA
> - music USB thumb drive removed:     0.150 mA
> 
> Would an iPod or smart phone "music" device draw more current? i.e. would
> the entire device be powered up even if stereo is off?
> 
> In my case, the new 40R aux battery I installed was only seeing short
> charge times via alternator during short trips. Alternator charge system
> improvements aside, if that battery only sees short charge times and a
> "constant" Amp draw of 5 Amps a day I'd guess that the battery would run
> down over the longer term.
> 
> During these colder darker months, it might help the battery if the stereo
> removable media device were disconnected. Especially if stereo is connected
> to the starter battery.
> 
> Neil.
> 
> 
> --
> Neil n
> 
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