Here's a simple project that indicates how much energy is remaining in your batteries.
It's a gauge for lead-acid batteries, It’s an LED bar graph voltmeter with a scale it starts at less then 11.5 volts up to 16 volts.
I have it hooked up to my solar battery bank so I can tell how much its charging when its sunny out to how much it has left when I’m using the batteries.
I also made the case that it sits in with my new 3d printer lol.
I will be posting the files if you would like to print your own case also will put case up on thing-a-verse
lets start with a parts list they should be very easy to find parts i had to only buy the leds since it takes 11 of them but get 12 and burn one for the led god for good luck lol.
U1- 7805, 5VDC, 1A. Voltage
U2- LM 3914N, LED Bar/Dot Driver
D1- 1N4002, 1 A. Silicon
D2- 1N5241B, 11VDC Zener
D3-Amber LED indicates 16.0 VDC
D4- Amber LED indicates 15.5 VDC
D5- Amber LED indicates 15.0 VDC
D6- Green LED indicates 14.5 VDC
D7- Green LED indicates 14.0 VDC
D8- Green LED indicates 13.5 VDC
D9- Green LED indicates 13.0 VDC
D10- Green LED indicates 12.5 VDC
D11- Green LED indicates 12.0 VDC
D12- Amber LED indicates 11.5 VDC
D13- Red LED indicates <11.5 VDC
R1- 390, 1/4W.
R2- 820, 1/2W.
R3- 1.4k, 1/4W.
trimmer potentiometerï R4- 10k
On/off switch your choice
A connection bus for the outside of your case if you use a case again your choice
Didn’t think I was going to make an instructable. so I didn’t make a step by step guide
If there is enough of an interest I will make one.
Have fun be safe