Batteries


I was seeing that there were recalibrations on the pack occurring every few days. So it needed attention. Then one day the IMA light came on. So It was time to remove the pack and start testing it.

Here is a link to Metrompg’s spreadsheet of detailed test data for his Insight pack that inspired the format of my spreadsheet.

This is the pack with the cover and carpet removed.

Here are the 3 charger/dischargers and the 2 power supplies used in the testing of all 20 sticks. One of the chargers is a MRC Super Brain 989. The other 2 are Super Nova 250’s.

After the pack was tested and all of the sticks were brought back to normal, I equalized the pack with a variac for 15 hours on 175vdc, then at 177vdc for a few more hours. The fan was run on 13.8vdc during equalization. Then the pack was re-installed.

It’s tough to see the gray duct tape under the 2 fan resistors that is used to cover the sharp edges of the sheet metal. This is where the 2 wires pass through to the outside that carry full pack voltage. Eventually they will be connected to a constant current grid charger that I plan to leave mounted inside the car.

This is the cooling fan for the pack. It pulls air through the pack.

Yesterday the Insight used cell testing was finally completed. I put 4 chargers and 2 constant current power supplies to work individually charging 6 sticks at a time. That way the discharger was always testing a stick of cells. It took about 5 hours to do the remaining 15 or so sticks. The diode balancer didn’t work fast enough. So I just used the shorting clips from the flooded nicads to discharge each cell in a stick on those sticks that looked like it could help equalize. I found 3 sticks out of 20 that were able to sustain 6 minutes at a 50 amp (8C) discharge load. The rest fell under that time. That’s 5ah of capacity. Since nicads have a bit of a Peukert factor, then I think an 8C discharge will show a lower capacity than the nominal 6.5ah that they are rated at. My constant current discharger is so incredibly useful for testing these nicad cells.

The next step is to remove the pack from the Insight and do the same testing to it. I am not sure with 80k miles on the pack where the testing times will fall compared to the used pack. I still have to decide what is more useful, fully charging or discharging the Insight pack before I remove it. In order to duplicate the tests performed on the used cell, I would have to charge the Insight’s cells until very warm like I did the used ones.

Here are some Insight nicad sticks. After being tested there is usually 1 or more weak cells. I add a jumper across the weak cell so testing can continue on the rest of the cells.

Here is the ‘production’ area for screening the replacement cells just in case my Insight has some weak cells. I will remove the Insight’s pack after all of these get tested. I really need to get the spot welder assembled so I can repair any weak cells within a stick. The mill will come in handy for milling out the spot welds to separate the cells.