Computer Monitoring of 12V Battery

[B Donovan]

Hi All,

I'm would like to monitor a 12V battery from a microcontroller or x86
controller.
I want to be able to make machine decisions based on the expected
battery lifetime, similar to how laptops can monitor their batteries.

The range of voltages I would like to monitor would be 11V-13V and I
have been having trouble finding A/Ds that handle that kind of voltage.
I'm guessing that I need to use a voltage divider to get the voltage
into the range that the A/D can handle. Would this be the right way to
do this?

Thanks,
Brian

 

[Dan Hollands]

Yes a voltage divider is the common way to go but if you have to "guess"
about that there I'm not sure how you are going to solve all of the other
design issues

dan

--

Dan Hollands
1120 S Creek Dr
Webster NY 14580
585-872-2606
[email protected]
www.QuickScoreRace.com

 

[Dave]

Yes a voltage divider is the common way to go but if you have to "guess"
about that there I'm not sure how you are going to solve all of the other
design issues

dan

Well put!

 

[grunt]

yes, Brian, a voltage divider is the right way to do it. There are
other ways, but they are cumbersome. There are microcontrollers with
built-in A/D converters.

Prediction of remaining useful battery charge would be specific to
battery type, battery age, and ambient temperature changes, but you
could make one that 'learns' , sort of.

I suspect that your solution lies in one or two simple comparator type
circuits that let you know when thresholds are crossed. Keep in mind
that a rechargeable battery in active service in, say, June, has a
different capacity two year later, probably.

good luck,
Geoff

 

[B Donovan]

Geoff,

Thanks for confirming my rusty memory. I was thinking of using a PIC
to do the monitoring. Thanks for the help,

Brian

 

[Frithiof Andreas Jensen]

Hi All,

I'm would like to monitor a 12V battery from a microcontroller or x86
controller.
I want to be able to make machine decisions based on the expected
battery lifetime, similar to how laptops can monitor their batteries.

Your life might be greatly simplified by the purchase of a charge controller
IC for the specific kind of battery you want to monitor.

Battery monitoring is mostly futzy guessing based on many parameters - since
you like PIC's the Microchip PS200 may be your friend:

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1335&dDocName=en022398

Because the parameters can be futzed with. Maybe you can even buy the
development board. Thats what I always do for a 1-3 off.

Maxim got similar things.