Testing the Motor

After wiring the batteries, we connected the 3 phase AC motor cable to the motor controller connection and the power and ground of the batteries to the controller cables. Below is a picture of the 3 phase cable connected to the controller.


The controller also requires 12V DC to operate, so for our first test we simply just hooked up a lead acid battery from our lab. The tricky part at this point was connecting all the pins, or leads from the throttle (potential meter), motor controller, and starter switch (having options of reverse, start/neutral, and drive). This took some time to figure out, but after using the manual and connecting our laptop to the controller to troubleshoot, we managed to figure out the problem.

After working together, we finally had all systems go. We are ready to push the throttle and see our motor move. Mind you we were all very excited and extremely nervous because this is the first time we will see our design in action after working on the project since June 2009. Take a look below!

Wiring the Batteries

There are 90 lithium iron phosphate batteries wired in series. Each battery is roughly 3.2V which gives a total of 300 Volts. This took about a day and a half. With all the wiring preparation for the BMS, probably about a week. We covered each terminal with duct tape so we wouldn't accidentally short a battery or shock ourselves. Yea, we played it safe.

A close up shot of a terminal. The wire is connecting the bottom layer to the top. The large red wire is high gauge rated for the large amount of current and voltage, while the skinny orange wires are connected to each battery node to read voltage for the BMS, which is not yet connected to the white inserts.

Jordan admiring the awesome power and thankful he wasn't shocked.

Another shot of the wired batteries. Two layers, 90 batteries, 300V, ready to light the tires!

Battery Management System

The battery management system's (BMS) job is to regulate how much the batteries charge and discharge evenly and within safe limits. Batteries cannot be over charged nor can they be discharged too low or they can become damaged. Also, lithium ion phosphate batteries do not all charge evenly, meaning if one charges faster than another it has the potential to reach maximum charge and beyond before the other batteries.

The BMS, designed primarily by Luis Breziner, is a circuit board whose job is to relay information back to the CPU, a National Instruments cRIO. The circuit boards will relay the voltage of the batteries they are assigned to back to the CPU, and if batteries are charging too fast compared to the average rate, the CPU will shunt them-- a resistor is turned on to limit the amount of current supplying the battery with voltage. This in effect keeps all the batteries charging at an equilibrium rate giving us control to limit how much they are charged.

The BMS gives us control over charging the batteries and also discharging. Since each board can read each battery's voltage, the CPU can determine how low each battery has dropped in charge, or voltage, and cut off the system before the batteries discharge beyond repair. Below is the process we took to assemble the boards once Luis finalized his design.

Luis pumped his BMS design is finished. He sent away for the chips and boards himself. Once they come, we have tons of work in store.

The material arrives and we have work. This is a group shot of us assembling the boards.

Pete and Jordan working.


Some parts needed a helping hand to solder.

Christophe and Pete finalizing the boards.

Above is about 90 BMS units, 5 to a board, 18 boards total.

Another look

Close up look.


Luis running a test on NI LabVIEW.


A board being tested. We hooked up and tested each board.


A close up look of the connections.




Luis Testing the boards, hard work pays off.