jbatx
I make stuff with things
Hey folks,
I have a strange issue with an Overkill (JBD) BMS delaying cell over voltage charge protection longer then it should ( I think ). I cannot explain it ...100%
The set up...
1. I'm working with a 16s 48v overkill bms
2. 100ah cylindrical cell modules from batteryhookup
3. Using the arduino lib to monitor and post data
FYI This is a two battery system. Both are 16s 48 with the same brand cells. Both have independent identical BMSs. Battery 2 is the one with the issue.
The issue...
One of the cells appears to be damaged. It will spike up as high as 3.86 while it's buddies are around 3.5* and it will discharge faster than them too. Over night, the voltage diff will normalize to about 5-10mv as the bms balances. I can see this graphed over time. The question is, why is the BMS letting it get that high? I have single cell cut off set to 3.65. The BMS does cut charging but it seems to be abnormally delayed in doing that.
The only thing that I can make logical is that the rapid polling by the arduino lib is causing a processing delay in the BMS. If that's true and you combine it with a cell that is rapidly increasing in voltage starting 3.6*, then I guess it makes some sense.
The BMS manual describes a delay between reaching the triggering voltage and the actual cut-off. However, I don't see mention of that as a configurable option.
I suppose, I could lower the over voltage cut-off.
Does this makes sense at all?
I have a replacement cell and I'll install it. HOWEVER, I don't want to ignore the issue of the BMS's delayed response.
What should I do?
I have attached a screenshot of the battery dashboard. you can see where battery_2 voltage diff jumps up rapidly above 400mv then starts dropping after the bms blocks charging. This is the current state as of just a about 60 seconds ago
I have a strange issue with an Overkill (JBD) BMS delaying cell over voltage charge protection longer then it should ( I think ). I cannot explain it ...100%
The set up...
1. I'm working with a 16s 48v overkill bms
2. 100ah cylindrical cell modules from batteryhookup
3. Using the arduino lib to monitor and post data
FYI This is a two battery system. Both are 16s 48 with the same brand cells. Both have independent identical BMSs. Battery 2 is the one with the issue.
The issue...
One of the cells appears to be damaged. It will spike up as high as 3.86 while it's buddies are around 3.5* and it will discharge faster than them too. Over night, the voltage diff will normalize to about 5-10mv as the bms balances. I can see this graphed over time. The question is, why is the BMS letting it get that high? I have single cell cut off set to 3.65. The BMS does cut charging but it seems to be abnormally delayed in doing that.
The only thing that I can make logical is that the rapid polling by the arduino lib is causing a processing delay in the BMS. If that's true and you combine it with a cell that is rapidly increasing in voltage starting 3.6*, then I guess it makes some sense.
The BMS manual describes a delay between reaching the triggering voltage and the actual cut-off. However, I don't see mention of that as a configurable option.
I suppose, I could lower the over voltage cut-off.
Does this makes sense at all?
I have a replacement cell and I'll install it. HOWEVER, I don't want to ignore the issue of the BMS's delayed response.
What should I do?
I have attached a screenshot of the battery dashboard. you can see where battery_2 voltage diff jumps up rapidly above 400mv then starts dropping after the bms blocks charging. This is the current state as of just a about 60 seconds ago
Attachments
Last edited: