Ideal Cell Resistance for the18650 battery cells / ORION 2

[jsimonkeller]

Hi everybody. I was wondering if anyone had any thoughts on the ideal cell resistance settings at different temps for the 18650 style battery cells found in Tesla modules.

My DCL is being reduced due to Cell Resistance and Temperature.

Pack DCL shows 629 at 90% charge, which feels low to me.

Maximum Continuous Discharge Limit is set to 1,200A

Cell Settings in ORION 2
• -15C | 2.03 / 4.06 mOhm |
• -10C | 1.78 / 3.56 mOhm |
• -5C | 1.57 / 3.14 mOhm |
• 0C | 1.40 / 2.80 mOhm |
• 5C | 1.27 / 2.54 mOhm |
• 10C | 1.18 / 2.36 mOhm |
• 15C | 1.15 / 2.22 mOhm |
• 20C | 1.13 / 2.12 mOhm |
• 25C | 1.12 / 2.06 mOhm |
• 30C | 1.11 / 2.02 mOhm |
• 35C | 1.10 / 2.00 mOhm |
• 40C | 1.08 / 1.96 mOhm |
• 45C | 1.05 / 1.92 mOhm |
• 50C | 1.01 / 1.86 mOhm |
• 55C | 0.98 / 1.76 mOhm |
• 60C | 0.90 / 1.62 mOhm |
• 65C | 0.81 / 1.62 mOhm |

Temperature Derate Settings are 1000A Limit at each temp between -5 and 45C

Screenshot from Live Cell Data

Thanks,

Jsimonkeller

[tom91]

What have you set the battery module type to? As there is a base resistance curve you cannot alter.

[jsimonkeller]

Hi Tom. In General Settings, for the "Selected Battery Cell (Profile Wizard), I have "Custom Cell Configuration".

I went into the Wizard and choose the Tesla 5.3 kWh (230 Ah) battery and saw that many of the parameters had changed, such as the cell resistance and top and bottom voltage and charge and discharge A limits. I chose not to blank everything out, so I assume all of my other settings remain.

Do you think this might solve the DLC limitation issue?

I can load up the old configuration first and save that to disk first and then try this configuration and see what readings I get and report back.

Thanks.

[tom91]

Yes you need to run a base Tesla module and then modify it to suit your application.

[jsimonkeller]

Thanks Tom. I changed that to the Tesla 5.3kw (230Ah) battery just to see what changed, leaving all other settings as is. From what I could see, the main changes were:

Charge Limit up to 300A from 222A
Discharge limits down to 500A from 1200A
Derates down to 500A from 1000A
Top and bottom voltage changed slightly
Cell Resistance settings changed over to much lower settings instead of the higher ones I was setting on my own.
20C .79
25C .76
30C .75
35C .74
40C .73.

I am not sure why I would now modify any of these settings, but would love any input. Still showing CCL reduced due to cell resistance and not sure which direction might help that one change to NO.

[tom91]

Your cells are very full so ofcourse CCL would be reduced, does not really matter why it just wil be.

You can change settings as you wish in all the settings tabs. It is really up to you how you want to set it up.