# Arduino EV battery monitor

**URL:** <https://community.sparkfun.com/t/arduino-ev-battery-monitor/26153>\
**Category:** Arduino\
**Created:** [February 24, 2013, 6:33pm UTC](https://community.sparkfun.com/t/arduino-ev-battery-monitor/26153 "2013-02-24T18:33:42Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dhymers](https://avatars.discourse-cdn.com/v4/letter/d/58f4c7/32.png) [@dhymers](https://community.sparkfun.com/u/dhymers)\
**Post date:** [February 24, 2013, 6:33pm UTC](https://community.sparkfun.com/t/arduino-ev-battery-monitor/26153/1 "2013-02-24T18:33:42Z")

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I just purchased an Uno R3 and would like to know what people think of this idea. (has anyone else done it?)

An arduino is _much_ cheaper than a Xantrex battery monitor, so I decided to see if I could make a battery monitor.

Sensing voltage should be easy and I assume I’ll need to build a prescaling circuit or a divider for the 128v sense.

sensing current might be a bit trickier ? using a 1000a shunt either 50mv or 100mv

these will fill up some of the adc inputs.

The really tricky part I assume will be an amp-hour/kwhr counter, basically calculating amps drawn(?) and an avg voltage.

For a display I have a common 16pin lcd which should be very easy to hook up according to a tutorial.

I’m new to microcontrollers and dont have much coding experience so I will probably be on here often asking about this 🙂

any suggestions before I dive in?

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**Author:** ![Mee\_n\_Mac](https://avatars.discourse-cdn.com/v4/letter/m/aeb1de/32.png) [@Mee\_n\_Mac](https://community.sparkfun.com/u/Mee_n_Mac)\
**Post date:** [February 28, 2013, 1:09pm UTC](https://community.sparkfun.com/t/arduino-ev-battery-monitor/26153/2 "2013-02-28T13:09:20Z")

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> dhymers:  
> The really tricky part I assume will be an amp-hour/kwhr counter, basically calculating amps drawn(?) and an avg voltage.

Not that tricky I wouldn’t think. Depending on how quickly you sample the current and voltage you should get a good idea of the amp-hrs and watt-hrs drawn/used. Whether that’s enough to yield a good range remaining estimate (which I assume is a final goal) I don’t know.