Hello again,Also, cooling in between cells should not be an issue in solar storage applications
I started celltests with my datalogger. I also measure temperature at the center of the cell during Charge/Discharge.
The cell lays down flat on a table, a precision digital sensor DS18B20 is taped on the upper center and covered by a 2 cm foam to eliminate ambient temp variations. Room temp is stable at 22° during tests.
I see a rapid temp raise as soon as charging/discharging starts, even I only use 15A. The total raise in temp during an 11h test is 5°C up to 30°C.
In a pack where all cells are fixed together with no space between, this means the cells inside the pack will rise more than cells on the outside.
With much higher currents in 12V packs, the temp may increase higher (to 40°?). Noone measure since all cells are packed together.
So I am still convinced it is better to leave a few mm space between cells since temperature rise affects lifespan (eventually by sticking vertical spacers at the border of the cell, so cells can still be fixed for mobile use).
What is your opinion? Is 30°C ( 5°C raise) normal for a 200Ah cell at a low 15A discharge?
15A X 1.8 mOhm would be 0.4W. Could that make it rise 5°?
What is the max temp a cell should get?
Graph:
Yellow= short cell charging 14A to 3.65V; 5 min Idle; Cell discharging 15A during 11.5h (red line). Temp rise in °C on the right side = purple line
The small decrease in the temp line in the beginning: I took off the foam to see if temp decreased.
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