Introduction: Make a Battery Protection Circuit (low Voltage Cut-off)

In this video I will show you how to build a simple lithium battery protection circuit, so you can power your homemade projects without ever worrying about over discharging your battery.

How to use lithium batteries safely: http://www.maxamps.com/lipo-care.php

More info on battery measurements: https://www.youtube.com/watch?v=cxkVxi9P0EA

Items you'll need:

Alarm circuit: http://www.ebay.com/sch/i.html?_from=R40&_sacat=0...

Relay: DSP1a-L2-DC5V

http://www.google.com/search?q=dsp1a-l2-dc5v (select one of the distributors - price is around $5)

Music by Kevin McLeod and Löhstana David

Comments

author
dtawom (author)2017-08-14

Really great tutorial. Looking at the alarm circuit I assume this could be used for a 1, 2, or 3 cell battery? For my application I'm just wanting to drain 1 cell at a time (cell phone batteries). After watching the video again it seems I would need to move the pushbutton and relay over 1 pin so they were in line with cell 1 instead of 2. It looks as If I'd have to change the relay bridge to the first cell instead of the 2nd as well and I could also skip the resistor as the circuit will be less than 5v. Are these the only modifications I would need to make this work for a single cell application?
My other concern is the power draw of the LED display. As I will be using this on cell phone batteries overnight (sometimes over the weekend) to run training cycles, I don't want the display to drain the battery to much further. Is there a way to setup this circuit so the display turns off with the relay as well?

author
FreekC1 made it! (author)2017-07-26

Hi Matt, I made your circuit, used a DE1a-L2-5V because this one is 10A rated :) The only change needed was to connect the switch to the first coil and the alarm system to the second. Thank you for the great circuit!

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author
RedBul Fuel (author)2017-02-21

Am I able to use this DSP1A-L2-DC9v instead of the DSP1A-L2-DC5v and just tap into the 3s balance wire? I am unable to get a hold of the 5v in Canada without crazy shipping cost or is there another brand I can substitute. hope you or someone can help

author
ArlingtonH made it! (author)2017-02-17

Based on the original, this is a version of the
“Battery Protection Circuit (low voltage
cut-off)” that I recreated.

I am using two combined latching switch to create a nine (9) pole-latching switch, which can be
connected and successfully operate any 2 to 8 cell lipo battery.

The latching switch turns on/off the unit as
design.

Two protection circuits will be use as part of a lipo battery 2000 watt 1 ohm resistors discharger
system for medium to large capacity batteries
used in RC vehicle.

The prototype works well.

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author
DanielJ245 made it! (author)2017-01-14

I have slightly altered the design to fit my needs, but it is basically the simpler version of the two

IMG_20170114_221423.jpgIMG_20170114_221428.jpg
author
barrymossel (author)2016-01-16

Wow, really great, just what I needed. Could you maybe link to all products used?

Is it necessary to use a 82 Ohm resistor or could I use a 100 Ohm one?

And what kind of push button do you use, as I guess it should be a momentary switch, but it looks like a latching switch?

author
seamster (author)2014-11-05

Very nice! This is a handy item to have.

I've wanted a low voltage alarm for my rc planes, but never sprung to buy one. I'm guessing this could be modified fairly simply to trip a loud buzzer, rather than simply cut off power?

author
ffink (author)seamster2015-09-14

the lipo alarm which is modified in this instructable beeps loudly when the trigger voltage is being reached. this instructable shows how to modify it so it doesn't beep anymore but instead cuts thr circuit. if you simply want an alarm but no circuit cut, just use the alarm behind the link.

author
MarcR6 (author)2015-07-23

To turn the circuit off, wouldn't it be more simple to add a toggle switch between one of the balanced connectors and the monitor, so that when off, it would read 0v and trigger the "alarm" which in turn triggers the relay?

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Bio: Hello! I'm Matt and I love making things. I'm always thinking of new ideas and how to make them as awesome as possible ... More »
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