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I have 3 ESPController boards and some spare “danger hot” boards (not sure what the proper name is). These have the attiny soldered in already from jclpcb.

I’m in USA WA. Speak up if you’d like some.

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I’m in Oregon. How many spare Circuit boards? Are the ESP controllers complete?

You can use a 12v relay but you will require a seperate 12v supply and will need to remove the jumper.

Definatley easier just to get a 5v relay with the jumper installed

I’ve just put together a new video on the ordering from JLCPCB and building process.

Hope it helps people out.


A post was merged into an existing topic: DIYBMS v4 Shunt Design and discussion

98 posts were merged into an existing topic: DIYBMS v4 Shunt Design and discussion

Hello Stuart,

First off a big thanks for the latest video, not only for having it setup to get them pre-built but also for how to do that process with them.

Everything did look to work properly but they did come back with a question about polarity and I responded with use the polarity in the picture. Heres another big thanks, the gerber files and csv files generate an excellent picture so I was comfortable with my response.

Does it make any sense to silkscreen polarity ? Just looking at the png files from github Im inclined to say no (there just doesnt look to be room), but thought it was worth asking.


Anyone have any thoughts on using one of these to power the controller?

I currently have a 3S15P test pack and I decided to wire one of these direct to the pack to power the controller. I now seem to get a lot of communication errors.

Anyone else tried one of these?

There is probably a lot of noise on the power signals. Try putting a large capacitor across the +/- input to the controller.

Thanks Stuart

Any idea what size i should use?

Start with anything you have! Probably 47uF or similar, just make sure the voltage rating is okay (5V+) and ensure you get the polarity correct if its an electrolytic cap. It may be worth also including a low value cap as well - like 100nF.

@John_Taves THANK YOU. Tonight I solder! Already have two small 7s packs ready for testing. And @stuart thank you as well for this incredible project. I look forward to the revisions offering more current and more capability.

Thanks Stuart

I may have found the culprit. Dodgy USB lead (aliexpress). I will continue to monitor.

Hello to all! Those who are experiencing problems in the work of DIY BMS. V3, cross charts and reboot esp. Impact of interference. On the esp, pull up the ‘RST’ and ‘EN’ pins to +3.3V with a 2.2kΩ resistor. On pins 3.3v and ‘EN’ , hang ceramic capacitors at 0.1mF relative to gnd. For fast real-time balancing, change the last line in the esp code from 20,000 to 500 - 1000
//Update Influxdb/emoncms every 20 seconds
next_submit = millis() + 500;

Hi @stuart, I would like to know if you want to collaborate with me and make an affordable commercial version that i can sell in South Africa. I have a small startup that lets people do DIY and I’m looking to make it more affordable to get a salable system for People. Let me know if you are instereste.

there is ATTINY at jlcpcb again
order quickly, there are only 99 pieces.
with this link you can always see which ones are in stock!


Winner winner chicken dinner. Thank you. Only ordered 15 circuits. Already have 5 controllers on the way so I’ll have spare controllers in the US.

Now only 84 pieces are available.
Congratulate yourself on your catch. I unfortunately ordered 20 pieces without ATTINY, I couldn’t wait any longer :frowning:

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I should have looked at the cost difference for 30 but didn’t want to hog them all. I’ll have enough for three 7s banks (10 circuits on hand already) which is all I need to get rolling.

Hello John_Taves and Stuart, wouldn’t it be better to talk about your conversation privately or in a new topic? Unfortunately, this topic loses a lot of clarity in your very long articles. Wouldn’t it be better to show your constructive results in this post? Please do not get this wrong!!!

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