Battery State of Charge Meter

 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.

Parts List
Integrated Circuits
U1- 7805, 5VDC, 1A. Voltage
Regulator
U2- LM 3914N, LED Bar/Dot Driver

Diodes
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

Resistors
R1- 390, 1/4W.
R2- 820, 1/2W.
R3- 1.4k, 1/4W.
trimmer potentiometerR4- 10k

Miscellaneous items
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

Comments

[Brose549]

I am interested in building an LED monitor like yours for the batteries in my EV project. I have 12 lead acid batteries. Can you give me any help how I might go about doing this. I know that there is probably a way without duplicating this circuit 12 times but not sure of how to go about building what I need. Any help would be greatly appreciated.
Bill

[Rainymadman]

Well I have a bank of six battery's and only use one batts are hooked up I think it's called parallel positive to positive and negative to negative
So total output will be twelve volts so metter checks state of all batts not on a one on one bassis
So when there being charged I can see the charge voltage and when there not being charged I can see there standing voltage or how long it takes to drain them
If I can help you with anything I'll try
George

[Dr.Bill]

Are the LED's bussed together on the positive side ?

[Rainymadman]

LEDs anodes are all connected

[Rainymadman]

Hey for the LEDs the cathodes connect to the chip except the red led
And the diode D1 cathode to the chip and diode d2 cathode to positive
That should fix you up the schematic is online

[Dr.Bill]

Never mind I got it but I still need the polarity of the Zener

[Dr.Bill]

How about the cathode on the zener, which way does it face ? The picture is not so good to see the band. There is light reflecting off the part.

[Dr.Bill]

This is just enough Instructable to get the job done. 5.0 Stars.

[Rainymadman]

Each led is 0.5 volts . The meter reads up to 16volts but you shouldn't be charging them that hi lol
I have a 150watt solar system setup with a four battery bank works well

[Dr.Bill]

I have 10/ 20watt panels to be connected to a 4 battery bank.
This looks like a very simple circuit, can you explain how it works to me ? Spicifically the need for a Trimmer.
I imagne you have to monitor the voltage personally while the bank is charging so as to not over charge ?

[Rainymadman]

Hey drbill the trimmer is to control the led briteness that's all so if it's setup outside you can turn up the briteness or if indoors turn it down since they do use power the dimmer the better and I put a switch since if I'm not around no need to waste current..
I don't have to monitor the charging at all but with this I can with just a glance. My charge controller works well. The circuit is very simple I hope I answered your question it's early and I'm off to work lol
Caio

[Dr.Bill]

Thank You. You have answered my question in full.
I am in the process of putting this 'Ible' together.
5 stars