Low Voltage Alarm and Shutdown Controller- DIY

**trader007** · 09-09-2009, 01:17 AM

big edit. i think i figured it out.

i have an m2 atx, but i want to have it tell me that my battery is getting too weak to start the car, and if it goes any lower just to have it automatically shut off the computer- leaving enough juice to start the engine when needed.

Here is a new mockup, great help from people smarter then me.

i will try this out and post back some pictures of the device.

**trader007** · 09-09-2009, 01:01 PM

as brought up by a fellow member of another forum, the only foreseeable problem would be the current that the two last relays draw when the alarm is tripped- because those relays stay energized, which means they effectively are "latched" so the m2 stays off even if the battery regains some voltage. if i used a normal latching relay i wouldnt have a current draw after shutdown, but i also cannot find latching relays locally.

if i used 400-ohm relays though, drawing .03a a piece, i would only be putting a .06a load on the battery... i figured this to be a negligible amount. well, i hope it is anyway. we will find out.