Unfortunately, I didn't have enough of the longer tabs so I couldn't arrange the batteries with 8 on one side, 8 on the other. Instead, I put them all together on one side. I put a thick mat on the battery tray floor to make the batteries level. Here is the pack shown with most of the BMS modules installed. They are installed in series, in specific order, beginning with the most negative battery first.
Shown here is an electronic mounting frame I'll be installing to fill the void on the right. It's made from wood and aluminum "L" channel. The frame has two purposes. First, it should prevent batteries from moving in the battery compartment. Second, it provides a mount point for the battery management electronics and a supplemental lead-acid 12V battery. Here are my initial thoughts on component position. The two tiny components on top are from the BMS system. The yellow box is a charge controller. It's needed so I don't cook the 12V lead acid battery due to overcharging. The box on the left is a DC-DC converter that will turn 48V to 12V to charge the 12V battery. The DC-DC converter will be left on except when the main pack gets too low.
POST CONSTRUCTION: Final configuration was close to this configuration. One change was to turn the blue BMS control unit so a 48V cable could pass through it. By doing so, it apparently measures current similar to how a clamp-on am-meter measures current. Although I don't have a scope to check this, I'm guessing that the speed controller would rapidly pulse 48V at varying frequencies rather than adjust voltage.
When the pack voltage gets too low, this cutoff module (see previous posting) will release voltage to the main motor contactor which will prevent further drawdown of the pack. For inputs it uses 12V and a ribbon cable input from the BMS. As output, it has a normally open relay that is energized if the BMS decides there is enough energy available. This will be put in series with the motor contactor circuit. This circuit will drop signal to the main contactor should the BMS detect excessive current draw. To construct the board, I used wire-wrap and perfboard. Once I find the circuit works as expected, I'll replace this board with an etched board.
As for how the batteries will be charged, I'll be charging them externally for now. At a future date, I'll be mounting the charger box in the front cargo area with some custom brackets fabricated from strap iron.
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