Sure, please drop me a PM
We already stock the module boards in the OpenEnergyMonitor store. We will have stock of the controller boards in the next week or so
Are your cells dropping that much when under load? Are the cells matched to the expected load ?
Hi Huey, just saw you post for some spare controller boards, i’m after some. Could you pm me?
Small capacity battery, voltage drop faster
stuart
Found a software limitation “Pack over voltage (mV)” 65500. I have 20 cells 18650 = 84000 mV
When you enter a larger value, it writes what has been saved, when the page is refreshed, it writes other different numbers.
That was raised a couple of days ago, can you please raise a bug on github.
Thé system was originally designed for 48V usage, but does work with higher voltages.
Many also talked about the problem of turning the relay on and off at the voltage limit values. In many systems, this is solved by two values. The first value is disable, the second is enable. Thus, by spreading these values among ourselves, we get rid of the problem of relay bounce.
Did you ever solve your issue with the CRC errors?
Similar setup to you, works fine when running on mains USB PSU, but get a few CRC errors when running on a stepdown converter connected to the batteries. Tried multiple converters and still same results.
Jon
As others have pointed out it could be your batteries, but yes, the rules need to have a recover value to prevent the oscillation. I made a version that had that with the rules, then rewrote that to be less generic. I don’t have rules, so much as I have max/min and recover settings for cells and the pack and temperature. Then you designate your relays to be either load or charge, and the logic of the code does the rest. You can also set the relays to respond to state of charge, but that’s only possible if you are monitoring current, which I am doing.
I don’t think I have the rules style code anymore, but I committed the one I am using to https://github.com/johntaves/diyBMSv4Code
Thank you. I’ll try
Can you track down where the CRC error is being introduced is it in the modules or the comms back to the controller?
What does the configuration web page show, are there high error counts on the modules?
So the chip used by JLPCB was different and ended with a “T” instead of a “P” I had to change the code to correct the error.
Just a note to say thanks mainly to Stuart and also others on here for all the work that has been put in over the last few years. I’m glad I hung in there as the v3 BMS nearly drove me nuts when it just wouldn’t communicate. V4 is so much better and improving all the time with the updates.
I started my battery storage project almost exactly 2 years ago when I collected my first cells from the local tip and started processing them. I now have just over 10kWh of storage in a 14s100p configuration though I’m only cycling about 40% of the capacity to prolong the life of the cells (all 1600mAh+ and 80%+ of original capacity still).
In the last 24hrs I’ve only imported about 0.25kWh hrs from the grid, roll on next summer!
My project is still a work in progress as I’ve not got current control of the Flatpack power supply implemented yet. This is also only a temporary location.
Hang in there everyone still working on their own build it is well worth it in the end.
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@Keith great powerwall. Really interested to see you using 1600mAh cells. I’ve been looking at 1500mAh for my own powerwall, working with multiple 7s18p banks.
Hi.
Some findings on our packs.
Don‘t use shared wires, even 5cm longs for the cell modules,
Always use 2 extra wires from each cell module to the battery tap/pole.
If we use - from first cell and + from first cell for the first module, but the same + wire from cell 1 as - for module 2 the meassured voltage on module 2 will rise when balancing starts on module 1.
The reason is that the minus voltage is dropping with the cable resistance on 800mA balance power but the + voltage stays where it was, because module 2 is not balancing yet.
Then we had a chain reaction up to the last cell, even if they were balanced first, all 16 modules start to burn energy
After cabling every cell module directly to the battery this „feature“ has gone.
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