Voltage Sense Only

Dedicated to support for the microcontroller based uSDC20D
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JoinedCOLON Sat Aug 04, 2007 1:24 am

Voltage Sense Only

Postby mcswensen » Sat Aug 04, 2007 1:35 am

Hey guys let me start by saying what a Neat little device you have here. I wonder if you purposefully manufactured it to fit into a radio shack 3x2x1 project box like a glove. THANK YOU!!!

so here's my question/post. My application for this is in an emergency vehicle controlling a tablet PC. I would like to make sure i understand your install guide correctly. I don't want the PC to turn off EVER except if the voltage drops to the point that the battery is in danger of not starting the vehicle. so if i do not use the MB PW switch wire can i use the unit to only monitor voltage?

is there a way to prevent the unit from going into countdown mode when acc goes low? if so cool but i also want to make sure that if the volage drops below my set point of 10.5 volts that it will shut off.

In my application the vehicle could be left for an hour or 10 either way when they return to the vehicle the tablet should be up and running unless the battery voltage got low enough to force a shut down.

Thanks in advance.

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LocationCOLON Portland OR

Postby zootjeff » Thu Aug 09, 2007 5:53 am

This would require a modification to the code, but I could do this for you if you want. By default it will count down when ACC goes low. You could wire ACC high all the time, but then the unit would never go to deep sleep mode.

The MB switch is optional you don't have to use it, but after ACC goes low, it will eventually pull the plug.

You basically want it to only pull the plug based on battery then? So for example, you park the car, the unit stays turned on while the engine is off. It would remain on for another 20 - 60 minutes based on battery voltage, then it would turn off?

If you turned off the tablet PC, then the uSDC would continue to energize the relay until the drain of the relay dropped the voltage at the battery to the threshold, etc. (witch would take a couple of days).

Is this the operation you would desire?

I have some wiring diagrams that you might want to take a look at.


Do any of the switch schemes do what you'd like here.


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