Warning

Once the BMS is installed, you'll be tempted to take your EV for a spin right away, under a false sense of security because a BMS is present.

Resist the temptation! Test first!

All too often, expensive battery packs were damaged, some beyond repair, because incomplete systems have been operated before testing would reveal problems.

Just because a BMS is present, it doesn't mean it's wired and programmed correctly.

The BMS, by itself, cannot protect the pack. The rest of the system must obey its command, otherwise there's nothing the BMS can do other than scream, while no one is listening.

Only after you have assured yourself that the entire system is protected, you may operate it normally and unsupervised.

Testing plan

Before operating a system:

1. Closely monitor the pack during its first charge cycle
2. Closely monitor the pack during its first discharge cycle

Procedure:

1. Connect the BMS master to a PC computer with a USB cable
2. After the BMS is powered, run the Lithiumate Lite application

Monitor first charge cycle

Closely monitor the pack during its first charge cycle, to make sure the pack gets fully charged, and it is not overcharged. This is a tedious job, but far less of a hassle than having to rebuild the pack due to damage from overcharging.

Procedure:

1. Plug the EV into the AC power, and start charging the pack from the charger
2. On the Lithiumate Lite application, select the "Status" screen.
3. Monitor the range of cell voltages, noting that the max never exceeds the Vcell-max setting
4. Monitor the current, checking its value is correct
5. Once the pack is mostly charged, at the start of balancing, note that the charger cycles on for a little bit and off for a long while
6. At the start of balancing, note that the number of "loads on" starts going up from 0
7. Note that the charger shuts off and the current goes to 0 when the voltage of the most charged cell reaches the Vcell-max setting
8. Note that the SOC jumps to 100 % at that point
9. Note that the charger comes back on when the voltage of the most charged cell drops back down to the Vcell-high setting
10. Note that the cell voltages get closer to each other as the cells are being balanced
11. Note that, once all the cells are balanced, the charger stays on longer, and the current slowly decreases towards 0
12. Note that, once the current is close to 0, the charger goes off and stays off

Monitor first discharge cycle during a test drive

Closely monitor the pack during its first discharge cycle, to make sure the pack is not over-discharged. This is a tedious job, but far less of a hassle than having to rebuild the pack due to damage from over-discharging.

This test takes 2 people: a driver and someone else with a laptop monitoring the BMS.

Procedure:

1. Turn on the ignition and start driving
2. On the Lithiumate Lite application, select the "Status" screen.
3. Check that current is flowing and that the reported value makes sense
4. Note that the SOC drops gradually down from 100 % as the battery is depleted
5. If torque reduction is implemented, note that the available torque is reduced whenever a cell is below the Vcell-min setting
6. Note that the current goes off when the minimum cell voltage reaches the Vcell-min setting (and comes back on should that voltage go back up above the Vcell-low setting)
7. Note that the SOC dropped down to a low level at that point

Completion

Congratulations: your BMS has been successfully deployed.