I have these, one for each series I activate them remotely with two relays and an esp01. but they generate a bit of interference with the DIYBMS reading, reflecting phantom current peaks, perhaps with the new version V4.5 and the greater speed and price in readings this problem will disappear. This active BMS of capacitors starts to equalize in a silly way as soon as the cells have 3.2 V (Life po4 system

A post was split to a new topic: V4.6

the new controller firmware at pylontech setting does not report min and max cell voltage to the venus os
is this normal?

i cant set it to victron setting then my sma inverter does not work

Hi Dan - for any problems, GITHUB ISSUES is the place to report those, genuine problems get lost in this thread of comments/questions.

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I’ve also been playing with the same active balancer. They don’t wait until 3.2V they balance all the time, there is only a circuit to prevent balance when under voltage (about 2.8V from memory).

Ugh. My main solar battery shows zero correlation between whatever happens below 3.3V and which cell(s) will cross the threshold of 3.4V first.

The other problem I see with these active balancers is they only balance when the delta is 0.1v which is actually quite a big range

These dumb ones from Aliexpress don’t have any clever logic in them, they balance all the time, which is bad!

I’m currently reverse engineering one (no plans to build my own by the way!)

@stuart I don’t know if this data maybe of use to you in any of your future designs but sharing just incase. I have been experimenting with two active balancers i) JK BMS 2A balance current , couple of mV measurement accuracy ii) NEEY (or Heltec) BMS 4A balance current , 1mV measurement capability. I am on octopus Go here in the UK and charge up over night at 50A (16s EVE LF280K) - Victron Multiplus2 setup.

For study purpose I connected both the JK bms and NEEY BMS to home assistant and recorded the attached plots which are for the max-min delta cell voltage over the balancing period. Over a few months during winter , I noticed something interesting on the JK balancer that while it is able to quickly balance and bring down the delta - it then starts diverging and the delta max-min starts to increase within the balancing period.

Balancing period = 1 hour (max) 16s pack kept at 55.2V (3.45 per cell). I say one hour max because it may terminate earlier at 4.30 am when octopus go tariff is back on standard rate.

The above issue was not seen in the NEEY/Heltec balancer.

This makes me think , 1mV measurement quality of NEEY/Heltec is more important than the balance current as JK @ 2A was also initially able to get the delta down quickly.

Just thought I will share for your consideration for ADC sections in your next design though this situation may arise only for those like me who charge at 50A ish. (50A at max …just some 100ma during balance)

Hello everyone. i need some help. I tried to edit the v4.5 board so i can make it into a single board of 14 modules but i failed badly.
My case is as follows , i have about 40 Kwh of li-ion battery already in use. I currently use Daly bms but i would like to use diy bms , therefore instead of having 14 modules and a bunch of wires , i would like to have a single board with 14 modules on it , already wired up RX to TX via coper traces and one single conector with 15 pins for sensing wires. Also i would like to have another conector for the balancing part , just the signal output so i can fit another daughter board with more powerful mosfets and bigger rezistors equiped with heatsinks and cooling fan. The esp32 controler board remains separate. I know it can be done but I have no idea how to do it , i copied the V4.5 board 4 times in kicad and tried to run traces from RX toTX but for some reason doesn`t work. Anyone here able to help?

I opted for this solution, a board in which I put 16 modules, I also tried to mount 16 modules on a single board and honestly, you can go crazy with thousands of ways and or having to give it a huge dimension. another option is to use my design and generate a 4-layer board

i love it. can i have the design files so i can order them?

Does someone in europe sell two or three new v4.5 controllers? (Only fully soldered by jlcpcb or other manifacturers)
Is there a channel to coordinate purchases?

If i try to order from jlcpcb, the components seem to be completely wrong placed, even off the pcb…

where are you from?

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Click on his icon!


what is the voltage sensitivity in the dynamic charging algorithm for?

how that remote update work?
i try to upload new firmware over the wifi, it says uploading in the web interface but the bms screen goes black and it never go further. then i have manualy to powercycle but then the new firmware isnt installed.

tried with and without running battery

Has @stuart or anyone here considered employing a simple coil economizer to the mechanical Relay 1 & 2 like the shown? Dropping the voltage to 1.5V across the coil reduces total consumption from .36W down to ~.11W while still keeping comfortably above the .5V dropout. Even if you only went to a very conservative 3.75V (which is the guaranteed open voltage) you still reduce to .27W. Not sure if there’s room on the current PCB layout to fit the components without stretching the board a little.

“Real” economizers feed the relay with a PWM signal after it engages. We can do that with the MCU – no additional components required.

Best to replace the '4148 with something larger (and with lower voltage drop) though, as the continuous flyback current is likely to cook the little thing.

real “economizer” Is usage bistable relay…
what is relay switched? In my instalation relay switched 20W air cooling vents. Relay consumption lower 1W. I not need research this…

Yeah, I’d like a bistable relay too. However I could not find one that’s rated for 60V 200A (must be able to disconnect under full load!) and that can be switched with 24VDC – or 12V or 48V or whatever DC that’s less than my battery voltage.

If you have a source, let us know.