One very smart LED, Battery monitoring like you've never seen it before
 

AutoSpeed - One very smart LED

http://i110.photobucket.com/albums/n...ps3vmzp7j6.jpg

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In fact, here is a battery monitoring LED that is user-programmable to run one of six different in-built maps. The single LED can show green, red, yellow and white, can also flash at different rates. The voltage is monitored as a rolling average over 2 seconds, is claimed to be accurate to 1 per cent, and will operate over 3.8 – 30V.

Map 1: Battery Voltage Monitor
Map 2: Vehicle Charge Indicator
Map 3: Vehicle Monitor , includes fake alarm
Map 4: Charge Indicator (Stealth Mode)
Map 5: High Res 10 step voltage monitor
Map 6: Minimal Monitor

The maps settings (the second lot of flashes) are as follows:

Map 1 – red flashes

Map 2 – green flashes

Map 3 – yellow flashes

Map 4 – red and then green flashes

Map 5 – yellow and then red flashes

Map 6 – yellow and then red flashes
search Gammatronix on ebay, between 20-30.00.

Trouble is I would need anywhere from 16 - 48 of those things to be a usefull BMS.

Id rather have something like this.

http://www.youtube.com/watch?feature...&v=CuR00e3yjBo

I like to have more precision and prefer a digital readout instead of colors to indicate ranges. For that reason, I have one of these

LED Car Battery Electric Cigarette Lighter Voltmeter Voltage Meter Gauge Tester | eBay

The downside is that it consumes 40mA and can drain a battery if left in a plug that maintains power after the vehicle is turned off.