Hello,
After almost three years of my first battery taken into use, I started to build a new battery.
https://endless-sphere.com/forums/download/file.php?id=215011&mode=view
I consider the 1st attempt as a great success. It is a 6S4P NCR18650PF pack soldered with fuse links at the negative terminal. Provides energy for a kick scooter. Seeing 40A peak (10A/cell) and around 15A continous. Since the building, the battery have around 100 cycles, used between 4,1-3,0V. Not measured, but no sign of degradation in real life use. Also, the difference between cells are not more than 30mV from each other, so no need of balancing. (Cells are protected by cell level LVC only)
Based on the above, It was logical to follow the same route with the new build. This case the application is to feed an 1,2kW Electric outboard (Haswing Protruar 2.0HP) on different small boats for river and lake operation.
As the motor is designed for 24V, I decided on 7S configuration. I set the capacity target to 500Wh, with the possibility to increase it to 1kWh.
I was checking the forum for a while, what would be the best, but still affordable cells for this application and came to the conclusion, for me there is still no better value for the money than the PFs. Finally I decided on 7S8P configuration, means 584Wh capacity.
During my first build, I made tests to find out the suitable size for fuse wire. I checked different diameter conductors that time (0,2-0,5mm) how fast burning out when an aged, almost empty, cold cell from a laptop (worst case scenario) shorted. That time I found, 0,3mm is a good size. In that application I did not care much about losses due the short bursts of high current consumption and the existence of cooling airflow. In watercraft propulsion, continuous full throttle operation without much airflow is a realistic scenario, extra heating has to be kept as low as possible. Test revealed, at the designed maximum continuous current of 6,25A/cell I get 22mV drop on a fuse link. That is 0,14W heat/cell, 7,7W for the entire pack.
After almost three years of my first battery taken into use, I started to build a new battery.
https://endless-sphere.com/forums/download/file.php?id=215011&mode=view
I consider the 1st attempt as a great success. It is a 6S4P NCR18650PF pack soldered with fuse links at the negative terminal. Provides energy for a kick scooter. Seeing 40A peak (10A/cell) and around 15A continous. Since the building, the battery have around 100 cycles, used between 4,1-3,0V. Not measured, but no sign of degradation in real life use. Also, the difference between cells are not more than 30mV from each other, so no need of balancing. (Cells are protected by cell level LVC only)
Based on the above, It was logical to follow the same route with the new build. This case the application is to feed an 1,2kW Electric outboard (Haswing Protruar 2.0HP) on different small boats for river and lake operation.
As the motor is designed for 24V, I decided on 7S configuration. I set the capacity target to 500Wh, with the possibility to increase it to 1kWh.
I was checking the forum for a while, what would be the best, but still affordable cells for this application and came to the conclusion, for me there is still no better value for the money than the PFs. Finally I decided on 7S8P configuration, means 584Wh capacity.
During my first build, I made tests to find out the suitable size for fuse wire. I checked different diameter conductors that time (0,2-0,5mm) how fast burning out when an aged, almost empty, cold cell from a laptop (worst case scenario) shorted. That time I found, 0,3mm is a good size. In that application I did not care much about losses due the short bursts of high current consumption and the existence of cooling airflow. In watercraft propulsion, continuous full throttle operation without much airflow is a realistic scenario, extra heating has to be kept as low as possible. Test revealed, at the designed maximum continuous current of 6,25A/cell I get 22mV drop on a fuse link. That is 0,14W heat/cell, 7,7W for the entire pack.