Reviving an undercharged BYD 11kWh pack

Nice project! I hope the battery will start work with the inverter.
Did you check the firmware compatibility between the inverter and the battery?
I have some experience hacking CAN bus battery interfaces, but this is probably MODBUS RTU. I am curious whether the battery or inverter is the master device? If you have some bus logs, we can discuss them here.
I will follow up with interest the repository about the reverse engineering process. I'm running an inverter with a custom HV battery and planning to update my BMS solution. So I will be happy to see how the BYD battery is made :).
 
Hi, any progress on the project pls? I seem to be trying to find similar solution with my Gen24 10kw Fronius... I am able to put together many times the size of byd battery for much lower price. Question is, what BMS to use or how to fool the inverter to make it talk to the DIY battery pack...
 
Hi, any progress on the project pls? I seem to be trying to find similar solution with my Gen24 10kw Fronius... I am able to put together many times the size of byd battery for much lower price. Question is, what BMS to use or how to fool the inverter to make it talk to the DIY battery pack...
I have all the collected log files here: https://github.com/dalathegreat/byd_battery just haven't had time to prioritize this project
 
Today I turned on a LEAF pack connected directly to the grid.
8-)


7ZdM8FU.png


More info on the project here: https://github.com/dalathegreat/BYD-Battery-Emulator-For-Gen24

This is a gamechanger for how easy it is to re-use old LEAF packs as-is for stationary storage.
 
Dala, this is just awesome! The above looks like you have also hooked up Leafspy to the battery directly? Do you have any wiring diagram to show how to achieve this? I assume you need an external 12v source to power the unit, then connect the canbus to it? This would be nice to be able to plug in and check the health of a pack without taking apart the entire unit.

Reading your specs, does this seem right to you?

Bluetooth OBD-II

Pin 4 - CGND? Battery -12V negative
Pin 6 - CAN High - Pin 1 on Leaf
Pin 14 - CAN Low - Pin 2 on Leaf
Pin 16 - Battery +12V Positive

Leaf (2013+)
Pin 1 - CAN High - Pin 6 (Bluetooth OBD-II)
Pin 2 - CAN Low - Pin 14 (Bluetooth OBD-II)
Pin 5 - Battery +12V Positive
Pin 6 - Ground? -12V Negative?
 
Dala, you are such a great resource. I really need to learn how to utilize software more effectively in my electronics projects!
 
Thank you for the link! And it worked! I was able to connect to it! Now I don't know how to read it yet, but is the SOH of 89% good for a battery pack? It was removed from a working car, but was in a flood, then left for over a year.

The deviation of 64mV isn't bad in my books.
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Also opened it to make sure water didn't get into it and it looked fine. Used the multi tool at an angle and it did a good job slicing through the silicone cleanly. I didn't time it, but it took me less than 30 mins without any fuss, then just used a 2in putty knife and cut through spots that wasn't cut through.
 

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Thank you for the link! And it worked! I was able to connect to it! Now I don't know how to read it yet, but is the SOH of 89% good for a battery pack? It was removed from a working car, but was in a flood, then left for over a year.

The deviation of 64mV isn't bad in my books.

Also opened it to make sure water didn't get into it and it looked fine. Used the multi tool at an angle and it did a good job slicing through the silicone cleanly. I didn't time it, but it took me less than 30 mins without any fuss, then just used a 2in putty knife and cut through spots that wasn't cut through.
Very nice! 89% is very good for a 24kWh pack!

Also 64mV at that low SOC% is amazingly good!

Just seal it back up and use it as-is! :)
 
Congratulations on getting things working - it's so much fun to gat a battery (bank) operational and with reasonable controls in place.

Agree on 64mv deviation as workable. I typically run 40-80mv max pack differences in my daily charge/discharge cycles. Since I don't go above 4.0v hi and 3.5v low / cell under 18650 MNC chemistry for long life - the fuzziness doesn't get anywhere near the max or mins. After 6-9 months of no balance the max will drift 20mv wider and then I do a touch up auto-level balance to bring it back to the 40-80mv range.

Here's a typical 50mv max difference over the 126 packs that make up the battery bank at 10am as things are charging....
1682355830358.png
 
Very nice! 89% is very good for a 24kWh pack!

Also 64mV at that low SOC% is amazingly good!

Just seal it back up and use it as-is! :)
Ugh thanks for the confirmation :( My dilemma now is it's too good for a pack to dismantle!!! That was my original goal, to extract it to add to my powerwall.. now I have to go find a cheap used 2013 Leaf with a defective battery, so I can swap the battery! It will be a good summer car since I usually have excess solar power during the summers. I'll look for the next few weeks and see what the classifieds say!
 
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