[ausev] need advice on power management doo-hickey

[Sarah & Erik]

You can also just switch the DC-DC on only when the vehicle is on,
just connect an additional relay to the keyswitch. You should be able
to switch the input or output of the DCDC, unless the DCDC has a high
idle load in which case you'll want to switch the input.

The only worry is if you have a small DCDC charging a small accessory
battery, the battery may never get fully charged especially if you
drive a lot at night. It would be a medium sized electronics tinkering
project to create a timer that started after you shut the car off that
would leave the DCDC on for an extra hour or so.

Erik

On Jan 22, 2008 8:24 AM, MLAB <mlibrik at att.net> wrote:
> One of my home-built EVs (the complicated and expensive one) sat idle
> for a couple of weeks waiting for me to address various little problems
> that it had.  During this time I unintentionally left the main breaker
> switch on a battery pack open.  This meant that a DC-DC converter was
> allowed to draw power, and it ended up draining the pack by the time
> that I noticed it.
>
> The simple way to avoid this problem is to remember to shut off the darn
> battery pack, but I'm wondering if anyone knows of a device that help
> guard against this sort of thing.
>
> Say there was a device that monitored current in the battery line and
> when it saw that a small current had been flowing for a couple of hours
> it would open a contactor and isolate the battery.  Normally, there
> would be either no current flowing (battery disconnected) or
> intermittent high current (vehicle in use), so it would recognize if
> there was a steady leak.
>
> Does anyone know of such a doo-hickey?
>
> --
> Mike Librik, LCI #929
> Easy Street Recumbents
> Austin, TX
> (512) 453-0438
> www.easystreetrecumbents.com
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