Arbol
100 W
Hello, I am thinking about adding a kit to my MTB. For the battery, I am considering a small 12s2p battery with 18650 cells. Basically, I need a max of 15A, which is the current of the controller I want (S06S). As a consequence, it would be good to have a current of 7.5A for each cell, a figure which is delivered by a few cells in the market already (or close to it). I have locally found a technician who can spot weld (they are a shop specialized in batteries). Some questions:
1. How many cables should a battery have? From the interesting report at http://www.electricbike.com/martin-cromotor/ I see the Sony VTC4 are put in small packages, and each package has 5 wires: two red, two dark blue and one light blue. The light blue one is for balance charging. Are the two red ones to connect to the controller, and the two dark blue ones to charge the battery?
2. Balance charging: I read the Sony VTC4 do not require BMS. I guess that Martin Cromotor uses a RC balance charger to balance the cells from time to time. The article says "so he can check the voltage of each individual parallel string if he wants". This means I should have a balance tab for each 2 cells (2p) or one for each 12 cells (12s)?
3. If adding a BMS to the package (which I believe is required for all batteries but the Sonys), the balance tap is completely unnecessary, right?
4. The also interesting report http://www.electricbike.com/high-current-batteries-that-are-not-lipo/ suggests the Samsung 20R and the Sony VTC4 are the best 18650 cells in the market. However, I see other interesting cells, such as Panasonic NCR18650PF (2900mAh), the Panasonic NCR18650B (3400mAh) or the Sony NC1 (2900mAh). I have tried to find a comparison among these cells in this forum, but I have not found a complete one. Is there a ranking of those cells, depending on durability, discharge rate and capacity?
1. How many cables should a battery have? From the interesting report at http://www.electricbike.com/martin-cromotor/ I see the Sony VTC4 are put in small packages, and each package has 5 wires: two red, two dark blue and one light blue. The light blue one is for balance charging. Are the two red ones to connect to the controller, and the two dark blue ones to charge the battery?
2. Balance charging: I read the Sony VTC4 do not require BMS. I guess that Martin Cromotor uses a RC balance charger to balance the cells from time to time. The article says "so he can check the voltage of each individual parallel string if he wants". This means I should have a balance tab for each 2 cells (2p) or one for each 12 cells (12s)?
3. If adding a BMS to the package (which I believe is required for all batteries but the Sonys), the balance tap is completely unnecessary, right?
4. The also interesting report http://www.electricbike.com/high-current-batteries-that-are-not-lipo/ suggests the Samsung 20R and the Sony VTC4 are the best 18650 cells in the market. However, I see other interesting cells, such as Panasonic NCR18650PF (2900mAh), the Panasonic NCR18650B (3400mAh) or the Sony NC1 (2900mAh). I have tried to find a comparison among these cells in this forum, but I have not found a complete one. Is there a ranking of those cells, depending on durability, discharge rate and capacity?