done, with detailed information
additional question
what is this calibration value 4095 for?
SoâŚI got it partially working but I am getting a lot of Bad Checksum messages. Also, when I plug the serial interface in, the screen doesnât work (it freezes)âŚ
Any ideas? The app is still updating so I know the device is runningâŚ
Hey guys,
Iâm selling off my DIY BMS stuff.
While I totally like this project, I just am not able to finish my build.
4x JKong BMS are now doing my batteries for over 1.5 years, its time to abandon this project for me.
I used to have a setup prepared for 80 cellsâŚ, 5 x 16 280AH Eve cells.
Life happened, now 3 x prebuild BYD 260Ah each and one DIY 280 Eve.
Running stable for a long long timeâŚ
Never change a winning team:-)
AnywaysâŚ
My hoarding collection is roughly this:
33 x 4.0 boards, the heatsink you see is with thermal tape
4.0 boards
30 x finished 4.40 boards. Heatsink is fixed with thermal epoxy (on 17)
4.40 board pic1
4.40 board pic2
picture of 16 with heatsink
20 x not yet finished 4.40 boards, all parts included.
20 4.40 boards new, incl. parts.
second picture
6 controller boards, not yet finished (all parts included)
controller boards
5 x new controller boards not finished, one with display, for 3x all parts included
new controller boards
I have 25x attiny, 20 to be used for the not yet populated boards.
Possibly Ebay is a better place to sell.
Attiny goes for ⏠10 there (UK) ( ⏠2.50 poland)
That is not where the enthusiasts are 
This community has given me a lot, I like to give back.
Iâm not giving away for free⌠absolutely not.
You also donât have to expect to pay 10 bucks for attiny
Just send me a message via OEM forum if you are interested to buy.
1 Like
I have a question about flashing firmware via the ESP32 controller board.
In the menu âAVR Programmerâ there are different module firmware for 4.40 modules:
V440 (be82379d)
V440_COMMS_5K (be82379d)
V440_COMMS_9K6 (be82379d)
Can someone explain to me what the 5k and 9k6 resistor values are all about?
I want to program an âEVE_v1.9Fâ module, but I donât know which firmware is the right one.
In which repo can I actually find the commit âbe82379dâ?
Is always written behind each firmware.
Thanks
Chris
Easy. Those are not resistor vales. These are baud rates.
THANKS!
So once 5000 and once 9600 baud.
What then has the firmware without specification?
- Read the source, itâs in the ATTINYâs 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 $10âŚ
I didnât invest to make profits.
Iâm 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
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:
Iâve 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
When people have the urge to read all 4700 posts, they will come across my learning curve with solderingâŚ
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 partâŚ
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 Iâm beginner at that part.
AnywaysâŚ
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.
Transport
10-20 days $10
8-15 day $ 15
3-7 day $ 32.50âŚ
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, itâs quickly an (envelope) parcel, where the price starts at $10
Bigger (thicker) starts at $20, like 250 gramsâŚ
More units is more weight, possible little more expensive.
Iâm not a business.
I donât 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 
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?
Yes!!
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 havenât 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 
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, Iâve tried 30 boards to solder the inimini tiny thermistors by hand with soldering ironâŚ
That didnât work out as plannedâŚ
(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 âxeâ 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 didnât make it (yet).
I could not see the thermistors, solder them etcâŚ
Older eyes and being inexperienced arenât a blessings for this kind of work.
