DIYBMS v4

Thanks, I always use twisted cables in my packs

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so the v4.2 boards and everything are ready to go?!?! :slight_smile: HAPPY DANCE!

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I ran a discharge /recharge test only at around 13amps (only have a small inverter here right now) and I experienced communication drop out every few seconds for the entire test duration, once I turned off the load it was fine, then same thing charging back up at 15amps. A couple modules also appear to have gotten ā€œstuckā€ with the load resistors on near the end of the charge, lost all comms until I unplugged each of them from power, once I plugged the module back in, comms came back right away.

Anyways still testing, going to change a couple things and try again.

Ok to help determine the root problem, when the charge at 15A is running do the green leds on the modules stay in sync - that is they flash in a line one after another or does the green led randomly double flash across all modules?

Hi, Stuart. I am trying to buy all of stuff to make this great DIYBMS. I will try to do with typical arduino pro mini boards, because I dont have skills to solder smd components.
Any way, the question is about voltage reference.
If you change it to 1.25v, I think that you should change these lines in your source code:

//2mV per ADC resolution
myConfig.mVPerADC = 2.0; //2048.0/1024.0;

To

myConfig.mVPerADC = 1.2207; //1250.0/1024.0;

why do you say that it is not necessary to change the source code ? I dont understand well.

This way, could I use a 2.5V reference ?

Bye,

It shouldnā€™t be necessary to change the source code when using the 1.25V reference because I have also changed the resistors on the board to match so the 2mV value is correct.

Yes you could use a 2.5V reference, however note that this would then be the LOWEST voltage you could read - probably more like 2.6V as the diodes stop working near their set point.

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Iā€™m 30 minutes into another discharge cycle with new cables I made this morning, used a telephone wire insteadā€¦ Have only had 15 packet errors so far at 15 amps, far less than with the other cables. When I do the charge cycle I will monitor the LEDs and see if I can visually see what is happening and report back.

it was on the module webpage, i clicked on each one and yes it does store it so no problem just user error :slight_smile:

Ok, sorry for my misunderstanding. I have to check all 4.2 version then, especially schemaā€¦ Thanks a lot for your quick answer.

Ok, I will use them with a LiFePO4 battery pack and I want to stop discharge a gap above 2.5V, probably much more than 2.6V. Thanks

ok new problem , I just need a clarification, one of my balance modules is not working now. its in the middle of the pack. the leds ā€œchaseā€ from one end to the other, but skip past this module. I cannot seem to figure out why its not working any more when it was beforeā€¦ if the comm cables are off (really just the rx), the green light flashes twice every 10 seconds, I thought that if there was a module that wasnā€™t working in the middle the leds would stop chasing at the module that had the issue. the other 6 modules show up as normal.

anyways i removed the module and reflashed with the test program, all worked as expected, reflashed module code, same issue, no comms with the controllerā€¦

Ok. There is likely a hardware fault, did you solder these yourself? Can you swap the module to be the first or last in the pack?

Yes, I used solder paste and toaster oven. I moved the module to the first position, led chase starts right after.

Very neat setup! What are you using for caps on your battery connectors, and did you 3d print the discharge holders?
Troy

As the problem moves with the module Iā€™d suggest there is a soldering fault.

Does the module show up on the web interface? Have you ever set the bank on this module to something other than zero?

The module does not show up on the web interface, it has only ever been set to bank 0. It was working fine, but just stoppedā€¦ I replaced the optoisolator, but that did not fix it. I did resolder anything that looked like it could be a dry joint, but didnā€™t work eitherā€¦ I also measured along all of the traces from the tx/Rx connectors back to the attiny and they were good. I am going to make a few extra boards tomorrow and run the soldering iron over all of the joints just to rule that out.

The module is passing the data packets down the line but not flashing the LEDs for some reason. Possible that the attiny pin has died driving the led.

Thanks! Yes, it is all 3d-printed



If you want to, i can upload those files to thingiverse!

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Multiple banks balance problem
Hi, iā€™ve a problem with a combination of 14 packs (2p7s). Iā€™ve splitted the 14 packs in 2 banks (bank 0 and bank 1). When the balancing starts, only the first 7 packs can get into balance mode! The second bank never starts to balanceā€¦ iā€™ve updated the newest controller/cell code, but it does not solve the problem. Any suggestions? Thanks a lot!

Nice setup, so you are running a 28v setup?

The button to set the cell balance voltage (normally 4100) only sets bank zero, you will need to manually set the voltage for each of the modules for bank 1