Battery Packs (applies only to 24v systems)

     Lets talk space for batteries. Above each wheel at the back there is 28" L x 5" H x 4" W on each side and 8" L x 8" W x 13" H in a dedicated battery compartment. This is enough space for 8 blocks in series of 10 paralleled cells (80 cells @ 60Ah) above each rear wheel and 8 blocks in series of 10 paralleled cells (80 cells @ 60Ah) in the battery compartment. We need 8 cells in series of 4 paralleled cells to make our 24v 24Ah (576watt) battery system. For economy it would be best to use 3.2v 6000mAh cells (32700 type) rather than the normal 3.2v 1100mAh to 1500mAh (18650). The 32700 cells are 1" diameter x 2.5" instead of 0.72" x 2.15" for the 18650 cells. 1152 watts is higher than the required 480 watts but I am upping it even higher to 1440 watts for range of 120kms. Fully expanded the trike could have a range of 360kms with 180Ah which is phenomenal. At $9 per cell, 24Ah is $576 but at 180Ah cost are bumped to over $2,295. A happy medium is to target 60Ah for $720. This will provide a satisfactory range of 120kms.

     When you place the batteries into a protective enclosure, you will need a positive terminal and a negative terminal and 8 wires going to the cells for monitoring and charging. In low end E-bikes they seldom have BMS charge protection and the charger is seldom carried with the E-Bike. At best, you will find avid E-bike users will carry a second battery pack to swap in as needed. I am not normal so mine will have BMS and onboard charge from AC and / or solar!
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Battery bank case

     For the batteries, we will have 80 cells arranged as 4 groups of 20 cells with 10 cells in parallel and 2 sets in series per group. Each group will measure 6.75" x 5.25" x 3". So to make the battery pack we need 7" x 5.5" x 12.375" minimum plastic box size. Provisions are included for a .5" top cover mounting lip. Acetate glue will mount the ends, and .125" x .5" block separation inside the 'U' form as below.

BMS charge monitoring (applies only to 24v systems)


     Our E-Trike will have BMS to protect the Batteries. Depicted below is a Passive BMS charge monitor board that can monitor 8 cell blocks. As a passive system, when a block is fully charged, it's LED lights and charging stops on that group diverting charge to the remaining groups. While all groups are charged initially together, any block that reaches full charge ahead of others stops charging.

     I included a four pin battery connection to service needs of the E-Trike and the 8 pin connection for individual battery charge monitoring. Due to the potential charge and drain currents, the four pin connector will need heavier wiring direct to the battery.
     The wiring schematic for the BMS boards is shown below. There are 8 identical circuits that each monitor a 3.2v group of cells.