diy solar

diy solar

JK-BMS-CAN with new Cut-Off Charging Logic (open-source)

MrPablo said:
Set the 'discharge_knee_v' to 3.5 in your YAML, and it will work as expected now that you have set UVPR to 3.1v.

I'm glad we're understanding what went wrong, but I'm frustrated that you were quick to blame the code - these batteries are not toys (especially the li-ion cells you have) and incorrect BMS settings could lead to a dangerous fault condition.

You should always:
- Ensure the hardware is correctly and safely set up. Connections, wiring, etc, must always be safe.
- Ensure the BMS is correctly configured for your battery chemistry.
- Only then can you utilise a project like the JK-BMS to ESP32 correctly.
Click to expand...
I'm glad we're understanding what went wrong, but I'm frustrated that you were quick to blame the code - these batteries are not toys (especially the li-ion cells you have) and incorrect BMS settings could lead to a dangerous fault condition.
Click to expand...

Also - I was not quick to blame the code and I don't do blame (as I know you guys did an intelligent hard work coming up with this solution) i initially stated it might have been something i touched at the start of logging my issues refer back to the beginning.

why would i blame the code when i have not a clue how to write simple arguments like you guys do.

i understand your frustration, but these things happen and yes i am very safe - i do think through my decisions both on paper and in my head multple times before i move to implementation.
 
MrPablo said:
One last point @chaosnature, I think I have mentioned this before to you. You are starting balancing at 3.0v, this means you are essentially middle-balancing your cells.

I would recommend setting the balance start voltage to 3.9v, perhaps 3.8v if you prefer. That way you will be top balancing your pack, the preferred approach for house batteries.
Click to expand...
Furthermore - Based on my above concept if the cells are uneven below 3.8 v according to the little I understand about how the system works it will use the lowest cells as the source of truth during the UVP and the UVPR operations...
 
Can someone do a recommend settings for both main battery technology types - I think it should be part of the release as there will be many who are not well learnant on this topic and it might help them - that is if the objective of this project is to get ppl to use the DIY solution without too much technical background.

just a thought - dont bite my head off!!
 
chaosnature said:
Can someone do a recommend settings for both main battery technology types - I think it should be part of the release as there will be many who are not well learnant on this topic and it might help them - that is if the objective of this project is to get ppl to use the DIY solution without too much technical background.

just a thought - dont bite my head off!!
Click to expand...
hey there, i´m personally an LFP Guy and could provide screenshots of my settings.
But could not give any advice for Li-Ion chemistry at all.

On a second thought, i don't want to recommend any settings to anybody who has a DIY Build battery - cause that person should know what he is doing before setting up the battery and connecting any BMS, Inverter or ESP Project.
That is my personal opinion and i must agree to MrPablos comment - especially with Li-Ion Cells you really have to be very careful not ending up in a total mess or worst...

there are dozens of very good and detailed informations on how to safely build a DIY Battery (youtube, here in the forum, blogs and so on). I don't see it as part of our project to give advice how to use lithium DIY Batteries.
If someone is not willing to learn the basics on the chemistry and how to build and use a DYI battery, i would highly recommend a prebuild battery pack instead

hope for your understanding
 
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ChrisG said:
Well scratch that update. Seems the ESP is rebooting or something about every 22 minutes. Ran for hours without issue. Get comms failure with battery, no data to HA, and the website on the ESP itself is not available for about 7 minutes.

All charging and discharging stops when this occurs.
Click to expand...
Ok, 1.17.3 definitely is not working. ESP M5Stack keeps rebooting. Pulled it off the system for now.
 
Along side, human readable time is now only getting up to about 42 seconds in HA.
 
MrPablo said:
It's definitely feasible, do you have any good reference for C-rate vs temp?
I use EVE LF304 cells, with rates as below:
View attachment 201484View attachment 201483
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I didn't realize *that* much derating is required :oops: ...

Based on @upnorthandpersonal analysis I thought that no derating (at very low temperatures !) was even necessary, since you'd just need an extreme voltage to be able to push that current.

In my case batteries were sitting at around 10-20 °C this winter and charging up to 100A (280Ah). So *barely* within limits :oops: ...

Each battery in my system is sized (breakers, cables, ...) for 100A RMS only. So you could say that the margin is "built in" in my case (unless I try to charge below 0°C, but BMS won't let me do that).
 
silverstone said:
Based on @upnorthandpersonal analysis I thought that no derating (at very low temperatures !) was even necessary, since you'd just need an extreme voltage to be able to push that current.
Click to expand...

This is correct. At low temperatures, the increased internal resistance will automatically prevent high C rates.
 
chaosnature said:
thanks anyways for your support MrPablo......
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Is it now working as expected?

I'm hoping so as the upcoming v1.17.4 has a couple of changes that might be good for you. In particular, the option to select a non-Pylontech battery protocol that is still compatible.

Solis inverters don't seen to respect the requested charge voltage correctly when using the Pylontech protocol. This can result in lower or higher battery voltages than requested.
 
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ChrisG said:
Along side, human readable time is now only getting up to about 42 seconds in HA.
Click to expand...
You're using v1.17.3 from @Sleeper85's GitHub?

There used to be an issue in older code where the ESP32 would reboot if CANbus comms with the inverter failed, but that was fixed several versions ago.

The last time I saw instability where the ESP32 kept rebooting, it was because the voltage supplied dipped below 5v at points.
 
MrPablo said:
Is it now working as expected?

I'm hoping so as the upcoming v1.17.4 has a couple of changes that might be good for you. In particular, the option to select a non-Pylontech battery protocol.

Solis inverters don't seen to respect the requested charge voltage correctly when using the Pylontech protocol. This can result in lower or higher battery voltages than requested.
Click to expand...
Yes it is Perfect at this stage - working as expected

you read my mind on the topic of the Solis protocol - I basically just finished testing User-Define protocol option from the Solis inverter, it worked fine except it did not allow me to change the Overdischarge SOC below 20 .

It was stock on 20, so I have gone back to using the Pylontech protocol - yes i know the values seem very low, but i had to set it low to get more capacity out of my system as at 20% there is still a lot left in the Batteries, so i use the JKBMS to control the Overdischarge SOC instead (keeping it at the operational values set on the Growatt GBLI5001 Datasheet)

1710179736198.png
 
MrPablo said:
You're using v1.17.3 from @Sleeper85's GitHub?

There used to be an issue in older code where the ESP32 would reboot if CANbus comms with the inverter failed, but that was fixed several versions ago.

The last time I saw instability where the ESP32 kept rebooting, it was because the voltage supplied dipped below 5v at points.
Click to expand...
Yes, using Sleeper85 code, cloned from Git. Using the M5stack. I've pulled it off for now, not reliable. The power supply is powering another test I'm doing with a separate ESPDEV kit and MCP2515 with no problem, working fine.
 
ChrisG said:
Yes, using Sleeper85 code, cloned from Git. Using the M5stack. I've pulled it off for now, not reliable. The power supply is powering another test I'm doing with a separate ESPDEV kit and MCP2515 with no problem, working fine.
Click to expand...
Yes, I thought it would be a long shot that it was a power issue, as you said it was working for a longer period at first.

When you get a chance, can you provide a view of CAN status over time, alongside ESP32 uptime? I'd like to see if the CANbus is going down before it restarts.
 
MrPablo said:
Yes, I thought it would be a long shot that it was a power issue, as you said it was working for a longer period at first.

When you get a chance, can you provide a view of CAN status over time, alongside ESP32 uptime? I'd like to see if the CANbus is going down before it restarts.
Click to expand...
Can't attach .csv unfortunately, but here is the data from this morning before I disconnected it.

1710195523927.png
 
MrPablo said:
Yes, I thought it would be a long shot that it was a power issue, as you said it was working for a longer period at first.

When you get a chance, can you provide a view of CAN status over time, alongside ESP32 uptime? I'd like to see if the CANbus is going down before it restarts.
Click to expand...
Sorry, grabbed the wrong item. Let me try a table here. Edit, tech is not cooperating.

1710196029757.png
 

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