Easy. Those are not resistor vales. These are baud rates.


So once 5000 and once 9600 baud.

What then has the firmware without specification?

  1. Read the source, it’s in the ATTINY’s platformio config file.

diyBMS-Code repository if I remember correctly.

I asked Stuard for price indication to sell.
He advised 4 pounds + price of Attiny

4.0 Cell module finished is $7.00 (33 available)
4.40 Cell module to solder is $7.50 (20 available)
4.40 Cell module finished is $8.00 (30 available)

While the cheapest attiny841 available I can find is $2.50, and regular price up to $10…
I didn’t invest to make profits.
I’m asking absolutely fair price.

Stuart advice 40 pounds for the new controller boards
The controller board is $45. All parts included
I have 2 x 2.8inch SPI Module, each $7.50. (when buying controller board)

I have 5 x older controller board, need to be soldered. (all parts included)
they include 4x relay boards, not the wifi modules.
Price $7.50 each

Slow transport is cheap but can easily take up to 6 weeks from Thailand.
FedEx (or other) is $40.
I charge half of it $20.
That is, if the order is above $100 :slight_smile:

Whole shebang:
83 cell modules, 5x new, 5 x older controller, 2x SPI, 5 extra Attiny841
incl globally transport = $750,-

The 5k and 9k6 refer to the speed of the communication (baud rate).

What is the eve module you refer to?

Hi Stuart, first of all thank you for your great work.

I used the forced module from vas (123mm specific version (v1.9)), see:

I’ve updated all the for sale cell modules to the latest firmware, 2022-07-06.

It was again a struggle to get it all working.

So I made dummy guide:
dummy guide diybms cell modules.pdf (359.2 KB)

Please share and make updates where needed :slight_smile:

When people have the urge to read all 4700 posts, they will come across my learning curve with soldering…

I have 27 (!!) 4.0 boards that need rework.
as far as I can say all 27 attiny841 are functional and working.

I had some troubles with the JST, and tried manually solder the thermistor inside the resistor part…
that is way too crazy tiny to do by hand!!
really… I spend hours and hours and hours
(that was before I learned about 177c solder paste, and bake it in an oven ad 180c)
So much simpler!!

Back then, better for me to just order some new boards and new parts (yes, JLC had the thermistor back in stock) then to spend more hours to do rework, as I’m beginner at that part.

27x 4.0 cell modules, need rework.
27 x attiny841, in great demand due chip shortage.

Price including global transport $100,-

Also available, 5 X older controller boards, with 5x relay.
Just 1 WiFi thingy.

Price $7.50 each.

10-20 days $10
8-15 day $ 15
3-7 day $ 32.50…

Regular mail with relay $7.50, takes 40 to 60 days (not tracked)
Regular mail without relay $5.00

Regular mail is price per.
As weight goes up fast, it’s quickly an (envelope) parcel, where the price starts at $10
Bigger (thicker) starts at $20, like 250 grams…

More units is more weight, possible little more expensive.

I’m not a business.
I don’t have all the numbers and rates.
This is indicative from what I can find using transport broker, to reduce the costs.

Directly via FedEx, think +$100 for one parcel :rofl::rofl:

anyone got a spare shunt board with smd;s mounted for sale ?

quick question. can you mix 4.4 and 4.21 cell modules on a v4 controller all in the same battery pack?


thanks Stuart. I remembered you stating that in a video awhile back but thought maybe it was only for the newer controllers for some reason

Donald, apologies for the delayed response. I haven’t played with the KG meter in a while. What firmware is on yours? I will power mine up and update if needed to see if I can repeat what you are seeing.

Sales went Ok for me so far :smiley:

What do I have left?
27 X 4.21 cell modules that are tested good, working and updated with the latest firmware.

5 X older controller boards (without the WiFi /Wroom / esp thingy)
With 5x relay boards.

Also 27 X 4.21 modules that need rework.

I could program them, but they have errors, like thermistor or led or loose connection (my soldering skills where not that fantastic at start.)

Besides this, I’ve tried 30 boards to solder the inimini tiny thermistors by hand with soldering iron…
That didn’t work out as planned…

(Way before I discovered solder paste and baking in oven)

Just a few random pictures of the ones that need rework are attached.

I have 5 spare Attiny 841, to be given away with the rework modules, just in case an Attiny has issues. (1 per 5 modules)

The good 4.21 modules : $7
Controller board with relay board : $7
The rework 4.21 modules $6
(One free spare Attiny per 5 rework modules)

Transport, depending on the order.
To UK / Europe is about $37,50. (Between 1200-1450 THB)

With orders below $100 I ask full transport costs.
With orders above $100 I ask $25
With orders above $150 I ask $20

The transport is via FedEx, 3-5 business days, + the days the local broker needs (usually 3-5 days also)

Regular EMS takes 45-60 days and is even more expensive at the post office.
(But if you insist… This is still possible)

I use Wise for international banking

This means that you can use any UK bank account to transfer to me in English pounds.
(Or Euro, or USD (+$5 for costs) or Singapore Dollar, … List goes on hahaha)

I use the conversion app from “xe” to see the exchange rate.
Usually Wise is close to them.

Just let me know!

Obviously the Attiny of the 4.21 boards can be desoldered and placed on 4.40 boards.

Not ideal, not needed (in my opinion, when you use below 80 cell modules) but possible.
Up to you as they say in Thailand!

Here some of my leaning curve modules that didn’t make it (yet).
I could not see the thermistors, solder them etc…
Older eyes and being inexperienced aren’t a blessings for this kind of work. :slight_smile:

Hi everyone. I’ve a small batch of fully assembled controller boards for sale - include both RS485 and CANBUS chips, headers, screw terminals etc. You would have to add your own TFT screen (if required) and ESP32.

Drop me a private message if you are interested, can post worldwide. Cost is £41 per board + shipping (normally around £10).

Last boards for sale :slight_smile:

11 X 4.21 fully functional.
5 X controller boards (older type) with relay.
27 X rework 4.21 modules.
(With 5 spare Attiny 841 for free)

(Heatsink are attached with thermal double sided tape)

If you are interested, send PM :slight_smile:

Hey, what those relay board for? How are you use them with diybms

the diy bms, the shunt pcb and the venus os with waveshare dual canbus hat

working with sma sunny island over bms canbus and the mppt rs 450/100 from victron is comunicating over VE can with the raspberry. the BMS has his own BMS can port on the canbus hat.

Is the web interface compatible to a Android Phone? I try to do a short loog, but hang…