diyBMSv4ESP32
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stuartpittaway
Discharging limited to 49V ?
I have tracked the charging / discharging curves for 12 days and found, that discharging stops always to ~49V. and it is not going lower.
My settings:
At a beginning, I have set the discharge limit to 49V, but have set it over week ago to 46.2 V as above settings shows. What could cause the 49V limit ?
Hardware/Software Versions Controller version (from PCB): 4.2 Processor: ESP32 Version: 4e72db94af375c391bad47b9b98507b3271b069d Compiled: 2023-03-29T08:22:59.136Z
Inverter limits are 46 - 55.8 V When battery voltage drops to ~49V, inverter log says; "The battery asked for a forced charge."
Discharging will also stop when the cell limit is reached "Individual cell min. voltage (mV)" - that would need to be lower than 2880 to work in your scenario - default is 3050.
I'm not sure, but does the 2880 mean 16S LiFePo battery (16 * 2880 = 46080) ?
My battery is 14S Li-Ion and that's why I have "Individual cell min. voltage (mV)" 3300 (14 * 3300 = 46200) 3300 is already little a bit under the charge knee. I tried "Individual cell min. voltage (mV)" of 3000 and 2900, but lowest discharge voltage did not go lower than ~49V
edit: I looked the battery voltage from HA's curve. Curve have a little deviation. Voltage is between 48,75 to 48,89 Counting 3050 * 16 =48800 (48,8V), seems, that DiyBMS uses the default "Individual cell min. voltage (mV)"
Inverter/charger discharge limit is set to 46V. When battery voltage drops to ~49V, inverter receives message from DiyBMS "The battery asked for a forced charge." But inverter doesn't start forced charge, because ~49V is more than lowest voltage 46V
Ok, DIYBMS never asks for a forced charge, unless you have the Force low State of Charge (default off) enabled.
I'm thinking this is a fault with the code in the inverter - are there any updates available for that?
Actually - on more analysis - what is the "state of charge %" when this happens?
"Force low State of Charge" is not checked. I'm running inverter with latest firmware. SoC is around 52%, when the inverter log informs "The battery asked for a forced charge." There's only the inverter and DiyBMS connected together with canbus, no other devices in canbus.
Ok, that is very strange - I was expecting you to say the SoC had fallen below 20%.
I'm not really sure what is causing that issue.
Wondering, if there's something stuck in memory, I tried to reprogram the firmware with full erase option, but no success. That didn't help, still stops discharging at ~49V
What inverter is this?
When the 49V limit kicks in, what does the "Dyn. Chg. V" and "Dyn. Chg. Cur" values look like?
Ínverter is Imeon 9.12
I used the MQTT to get values to Home Assistant and graphs shows at the point of "The battery asked for a forced charge." "Dyn. Chg. V" = 53,8V "Dyn. Chg. Cur" = 160A
Ok, very strange as the BMS isn't asking for a low voltage. Was the state of charge higher than 20% as well?
Yes, SoC was more than 20%. Maybe logging all canbus messages with time tags could show something. Any suggestions to make a logger ?
This still feels like a problem with the software in the inverter, rather than diybms. Happy to be wrong though!
I don't have any other suggestions for you, CANBUS logging is probably a good idea, but diybms never requests forced state of charge.
I play with Charge/Discharge configuration check boxes and inverter log says ; "The battery asked for a complete charge to rebalance cells voltage." But inverter didn't start charging.
Strange things happens.
I uncheck all check boxes at Charge/Discharge configuration.
Just changed the 'Under voltage limit' to 45V in 'Current & Voltage monitoring' and pressed 'Save advanced settings', screen shows;
Those check boxes were just unchecked.
Hi @deekoowee sorry only just noticed you updated this ticket.
The two messages will appear automatically if the charging parameters are exceeded - for example over voltage or temperature. The controller will ask the charger to stop.
They should only be transient though, and show for a few seconds before being cleared and normal operation resuming.