Battery monitor LED circuit

[L10N37]

Hey guys,

I noticed most battery indicators either turn on when the battery needs charging, or have multiple LED's to show different levels. I just came across this.

http://picprojects.org.uk/projects/vmon/

You would need a PIC programmer (which is dirt cheap) but the HEX code is there ready to put on the chip. I'm sure you could tweak it for lower voltage readings. I guess the source code would need modifying to change the distance between voltage drops for the different colours though.

 

[DuHasst0]

That monitor for the voltage isn't bad but its mainly for a 12v circuit and I noticed that you won't be using a 12v circuit. Close but not 12v. I would build DaftMike's battery indicator circuit since its inexpensive, and has no need for a PIC to do all of the analyzing of the voltage data. That and if I remember correctly DaftMike's circuit runs on like 40ma which is perfect for portable projects and the one you posted is used on a Bike that has an alternator of sorts to keep the battery at 12v.

 

[Hermaphroditus]

"above 15.1 volts the LED flashes orange ( red+green mixes to give orange)
between 15.1 and 13.2 volts, the LED is steady green
between 13.2 and 12.4 volts, the LED is steady red
below 12.4 volts, the LED flashes red
The software applies 1 bit (0.07 volts) of hysteresis to these set points."

I guessss that's neat. A bit unnecessary. You don't have to worry about the flashing orange for overcharging because your protection circuit should take care of that. Other than that I feel it'd just draw too much current. You will always have a light on, so you'll always be drawing excess current. Tweaking the values in the code to make it work on 7.4?V aside ('cause it's not that big of a deal usually), there are better implementations of low battery indicators. Also a lot of this logic is designed for charging batteries, the voltage ranges and such. I guess this would be neat on a battery charging circuit? But a bit unnecessary there, too, as a proper circuit will stop charging when it should flash orange, as to not damage the batteries.