OpenEnergyMonitor Community

DIY Lithium Battery Balancer and monitoring (BMS)

Hi guys looks like I’m late to the party here
Have emonpi and building two DIY powerwalls one from 18650 the other Phev batteries

Is there a quick start or build of materials guide ?

There is a parts list here:

Here is a list of where I bought my parts:

Youtube Videos:


thanks you will order the components this week have a steady steam if stuff from ali express every week postman probably wonders what the hell I do

never had a board printed before though what files needed to be sent to the maker etc is one recommended sorry for the questions



You need to upload the Gerbers files.
Download github repositorty and unzip it
Open the Bms Curcuit folder
Now you should see a folder called Gerbers.
Zip the Gerber folder so it can be sent to pcb maker people.

Yeah. I get a least two small packages every day from china lol

very impressed can see how it manages balancing and monitoring

Sorry for the multiple questions

can it also stop over charging and discharge would like to keep my batteries in side a safe delta of voltages to have them stay in a healthy state

See on the git hub page about been in the UK and have FIT want to AC couple this is my situation also wondering how others have done it? if I was going off the commercial would be using sofar solar or solex retrofit

thanks again


If you wanted overdischarge/overcharge protection you could attach relays to the charge input and discharge output of the batteries and connect the relays to the esp8266 and trigger the relays accordingly to your needs. If you’re using a solar charge controller (mppt) most have the options for setting battery max and min battery voltage.

If will also need a esp8266

I have several esp8266 of different types thanks

Anyone have the entire parts list in an aliexpress wishlist so i can just go “buy all the things!!!” :slight_smile:

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I can make one, however not all the parts are avaliable on aliexpress


Jman_brosef, I also have a few problems getting all the items. Some things are just not found and i even found 1 item that you could only order in 1000 folds … thats a bit much when you need 1 per board haha!

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Wish list (work in progress):


Thanks Jman_brosef,

I found out the attiny85’s aren’t sold anymore, but i got an alternative:
order them as 3 pieces at a time, else you pay additional shipping!!

And this one is a bit cheaper (its cents but still …everything counts!!)

Same goes for this one:

I can’t find bend jst connectors on alie, i have normal ones already so i’ll be useing that i guess :smile:

I am a bit reluctant to order the pcb’s don’t know why but still first time :slight_smile:

I ordered just about all my components from Ali as well, will see about checking mine against the wish list posted to see if i ordered any different. I may be installing mine this weekend, just still working on the control code for grafana but can at least get the monitoring in place.

Yes they are! Microchip haven’t made the ATTINY85 end of life - its still in production.

I used the ATTINY85/V variant which has a wider voltage input range - although this won’t make a difference to the circuit.

I found the ATTINY85 chips are cheaper to buy from Farnell than AliExpress if you are a UK purchaser. The 10Mhz version is fine as were running at 8Mhz.

I’ve used straight ones as well although the right angle ones are available.

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Those are the ones i bought and they came with cables with female connectors also. I got my attiny85’s from ebay but as stuart mentions for UK sellers farnell is just as reasonable and far quicker delivery.

I meant not in the link in Jman’s wishlist :wink:

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Hey guys;
I have ordered pcbs and the parts from a mix of newark/ebay/aliexpress.

I am excited about this project. I do have doubts about my depth of knowledge to pull it off though.

I got here by way of Colin Hickey’s youtube diyBMS/diypowerwalls. I too use Grafana/InfluxDB. So I am glad for that addition to this project.

Hopefully you will not mind some questions every now and then.