Traction battery power wiring

The 72V battery pack was wired keeping in mind that the wiring should be able to provide up to 400A for short periods. Most of the connections were done using power terminal connectors purchased togheter with the batteries from www.ev-power.eu. As the batteries were not assembled side to side, most of the power terminal connectors were too short and their holes had to be slightly modified to make the connections possible.

A 400A 75mV shunt resistor was mounted on the negative terminal of the battery pack to allow battery current monitoring. A 400A ANL type fuse was mounted as close to the positive terminal as possible. The cables used have a cross section of 50mm^2.

The battery management electronics will be wired next followed by the first charging of the traction battery pack.

Mounting electronic enclosures

A mounting stand was made for the enclosures including motor controller, battery management system and relays. The stand was mounted between the original motor mounting point shown on the left and the gearbox frame.

The stand was made using suitable steel rods that were welded together. It was then painted with zinc spray and a thick layer of black steel paint.

The wiring for the 72V battery pack can now be finished which will allow a first test drive with decent batteries! The wiring of the 12V system will have to wait until its battery pack and battery management system enclosure have been fixed on their places properly.

Wiring the battery management electronics

Both 12V and 72V lifepo4 battery packs will be managed by cell balancing modules (CBM) and a protection circuit module (PCM). Both are easily available and simple to connect. One CBM will be connected parallel with each cell and the PCM needs a connection between every cell. Although these connections are simple, the amount of them make this step quite demanding.

A half way wired 72V battery management circuity is shown in the picture. The PCM is shown on top and below it lies 24 CBMs. Once this is fully wired it will be mounted in a 240x190x90 mm enclosure. The connections to the battery pack will be done using 1,5mm^2 wire with a fuse located close to the terminals of the battery pack.