BMS Bubble
My plan had been to mount the Battery Management System unit in the front battery box, in the void near the steering gearbox. There is enough room and I had everything mounted when I realized there was a problem. The Orion BMS 2 wiring manual clearly states:
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| A BMS under glass |
"The voltage tap connectors must be DISCONNECTED from the BMS when being wired or when wiring is being modified for personal safety and to prevent damage. Wiring while connected to the BMS may pose a personal safety hazard and/or fire risk since the remaining wires within the cell group can become electrically ‘hot’ due to internal protection diodes. Additionally, wiring with the BMS connected significantly increases the risk of damage to the BMS."
Because 4 of my batteries are in the rear of the car, this means I can't connect the front battery cell tap harnesses to the BMS until everything is in the car and connected together. Once that's done there is not enough room to reach into the void and connect the wiring to the BMS.
This means relocating the BMS to a spot where it can be reached once all the batteries are wired to each other. Paul has his in the car where the factory heater blower was located but that uses a lot of precious cabin space. I want my BMS closer to my batteries. So I came up with a plan to mount it to the back of the front battery box.
Because of space limitations when lowering the battery box into the engine compartment, the BMS must be mounted after the box is in the car. Furthermore, the BMS needs to be protected from the elements, such as water and road debris. But it needs to have access to the five wiring harnesses and over 100 wires that plug into it.
Since the rest of the box is skinned in clear acrylic, I came up with a plan to build a "bubble" that fits over the BMS and seals it to the battery box.
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| Bubble mounted to skin plate that bolts to lower rear of battery box, with access holes for high voltage cables, main BMS harness, and rear cell tap/thermistor harness. |
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| Rough fitting the bubble and testing harness routing |
The bubble is open internally to the access hole in the rear of the box so the BMS has the ability to ventilate to the rest of the box, allowing heat dissipation.
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| Moving the BMS out of the battery box freed up some needed space for a monster 500 volt, 700 amp fuse in that location. |
