Monitoring 12 volt batteries

[Guest]

Something wrong with the charge circuit on my natural gas generator right now. I noticed that it missed its self test and sure enough the battery is dead. The question is: what is the best way to monitor battery voltage in homeseer? I have inputs on my alarm panel but they are not built for 12 volts. Same with the ADIO - it is only rated for 10 VDC. Ideally, I would like to be able to monitor the actual voltage and not just a trigger at a certain threshold. Ideas?

[Rupp]

Here's a neat little kit that you could connect the speaker output to an X10 univeral module or powerflash (can't remember which one does low voltage) or even a Z-Wave door/window sensor to alert you via HomeSeer.
http://store.qkits.com/moreinfo.cfm/FK915

[Pete]

Not sure if this discussion would help:

http://cocoontech.com/forums/topic/1...terys-voltage/

I get an actual voltage from the battery on the HAI OPII panel/HS plugin. On the secondary panel I have a connection to the primary panel with just triggers an NO switch if the voltage on the battery on the secondary panel drops. I also have NO/NC circuits on the whole house surge protector should the voltage spike.

Here is an Arduino discussion revolving around similiar topics.

http://arduino.cc/forum/index.php/topic,6540.0.html

[mrhappy]

Could you not do it with a potential divider? If you had the top resistor as 20k and the bottom as 100k then you would have:

Battery voltage - input voltage - approx digital value

12v = 10v = 255 (if 8 bit)
9v = 7.5v = 192
6v = 5v = 128
3v = 2.5v = 64

In HS then you run a simple script that converts the AtoD value into a voltage.

Not sure whether there are additional things to think of like if the battery is connected to something else (the generator starter), someone a bit more electronically minded might be able to offer an opinion.

[Guest]

Thanks for all of the quick replies. I think that the voltage divider is probably the route I'll go. Seems pretty easy and I get actual info about the state of the charge. I could probably even determine if the charger was charging or not. Usually they charge at something like 14 volts (or more). I suppose to get enough range I should build it for something like 15 volts so a 50k top reisistor and a 100k bottom should work great.

Thanks,