I have previously used the LeafBMS and am now considering to switch to Thunderstruck slaves.
Because I have problems with extended sensing wires.
How do you guys set sensible discharge and charge curves?
My understanding is that the Thunderstruck slaves give me all the cell voltages, do balancing, great, maybe the MCU does SOC calculations, but I have to set my own dislim and chglim.
I had a bit of a play with a regression tool and came up with the following for curves at 17 degrees, does that look sane for 96S 40kWh Leaf cells?
Formulas for x as SOC from 0% to 100%:
Code: Select all
chglimA = -x*x*0.026 + x*1.59 + 101 //quadratic approximation
dislimA = min(200, x * x * 0.5) //quadratic then flat from 20% SOC upwards
All at 17 degrees:
At 95%/4105mV allowing charging @ 20A?
At 4%/3238mV allowing dislimit @ 8A? (would be heater only I guess)
At 15%/3342mV allowing dislimit @ 113A?
At very low state of charge limiting the charge to ~100A? Should that be lower?
Thoughts? Code isn't a problem for me, knowledge of Lithium more limited, so your input would be appreciated.
CSV attached.
Edit: Had some offline conversations, it sounds like others are just whacking in constant-current during their charge and keep an eye on the temperature themselves, who is in that boat? Should I just be more brazen and do that too? Am I overthinking this?