Battery State of Charge Meter

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Introduction: 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


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user

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33 Comments

I'm a novice at this and would like to build it. Would you be able to make a guide?

2 replies

I'm not up to building a guide but I'll try and answer what ever question you have not sure how much of a novice you are but you need a breadboard to build and test this circuit before you commit it to a board so get all the items on the list first

what specs of zener diode if im going to use in 48 volts?i really need help btw.. this device is great but i need to make it in up to 48VDC..tnx

Hello, I am searching for simple battery charging indicator. I am using a 4 volts 1 amp lead acid battery and charging the same on 3 Watt solar panel. It charges fine with existing circuit but does not have indicator. I just need 3 indications 1. Battery low - to indicate charging should be started 2. Battery full - to indicate charging should stop 3. Charging on indicator, can some one help please

user

Would it be possible to put a large resistor on the input to test for voltages up to about 300 volts DC?

user

Would it be possible to put a large resistor on the input to test for voltages up to about 300 volts DC?

can u give us a picture of this when it is working PLZ!!!

1 reply

I lost every thing when sandy (big as storm) flooded me out
Sorry

Huh. I wouldnt even have the amber lights there. Any thing over 14.5 should throw a switch and disconnect the solars from the battery because thats a serious over charge. If 15 volts lights up you have issues.

1 reply

That's why the lights are there or how else would u know you had an issue

Does it only work with batteries ranging from 12V onwards?? What if i were to use a 12V battery then? Will it automatically shift the range? Cool project by the way. From Malaysia :)

1 reply

Hi berine
Thanks
It's a meter that will tell you what the current state of charge is .
It starts at <11.5 volts goes as high as 16 volts.
On my list of parts it shows you what each light means
I hope this helps you if you need more info just ask
And let me know how you make out
George

men it is too hard to find LM3914N.but i found one on the internet but it is like 6.00$ men!!!

Thank you for this project, I'm trying to make now. Greetings from Spain

1 reply

Hey your welcome let me know how you make out

Thanks bro I'm making This Project.but I don't have the lm3914 and 7805 LOL.but don't worry i will get it and make this project.this is my first thing that i'm making from instructables.

1 reply

Hey your welcome let me know how you make out

Thanks for replying,
I have tried online, like looking for similar voltage indicator but its not exactly what I want thou =/
I should have said before but yeah so the reason why was because Im making a 'solar phone charger'. For my iPhone 5 and thats why i wanted to know if you knew how.
With this indicator whenever im charging the batteries in the circuit i can see if they are fully charged!

Thanks for your time!

Hey there, is it possible to make a 0v-5.5v led inductor??