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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