2021 Nissan Leaf Battery Data
1N4BZ1BV5MC555761
Post Battery Module Swap Issues
Hey Guys. I have been collecting data on my nissan leaf after the battery module repair to verify that everything is in working order. Unfortunately we are no better than we were before , if not slightly worse.
Here is what’s going on , & there are two big problems that I am noticing. The Modules that were replaced in the battery pack do not appear to have been properly balanced with the rest of the cells / modules before installation. So the voltages in the new modules are way higher than the rest of the pack. I am noticing a 220mv to 300 mv difference at the top of the pack. This range should really be 50mv to 30mv.
Post Battery Module Swap Issues
This is what's happening at the top of the pack. This is at 100% SOC according to the in vehicle BMS after sitting on 240v charging overnight. These new modules are so much higher than the existing ones. The BMS is thinking that the battery pack is fully charged due to the high voltage reading on these new group of cells. It is not fully charged however. The true SOC is around 86% and the battery is only holding 47Kwh’s of energy when it should really be topping out at 56 - 58kwh of usable driving range. It is a 62kwh pack with about a 5kwh buffer. You will see as i go on that this 47kwh that it is maxing out at I cant even use nearly all of it due to another issue I will demonstrate.
Post Battery Module Swap Issues
So we started out with 219 rated miles , reset trip A and drove our normal commute for a few days which is majority regular streets 45- 55mph, minimal highway usage. We did this all the way down to the bottom of the pack to try to let the BMS see the full spectrum of the battery pack from top to bottom. Everything was going good until we hit 65% SOC. I will attach a video here to view. Right before the recording of this clip , as mentioned we were at 65% SOC. We were doing a quick highway drive , only 2 exits going home that evening. Here is the second large issue affecting this battery and it is at the bottom portion of the battery pack. WEAK CELLS!!
https://drive.google.com/file/d/1gjQiu6Mmqn7qoeClk_v8b7WzNqCiEFRZ/view?usp=sharing
https://drive.google.com/file/d/1_wr3Dt1pX0wuC9xseNRK3mCx70L-begx/view?usp=sharing
Weak Cells!
The Leaf battery pack is only as good as its weakest cells! I can't stress that enough, you will see how this is hurting this car at lower states of charge. As pack voltage decreases , and these already weak faulty cells become under load, they drop their individual voltages rapidly, causing the BMS to think the car is at a much lower SOC than it actually is. As you see in the video , we go from 65% (off camera just moments before) to 50% all the way down to 3% and by the end of the videos sitting in park , back to around 55%. This was the original reason for the car coming in for repair the first time. This issue has not been resolved
To recap before moving on. At the top of the pack ( full state of charge) we are suffering from the car not taking in the full amount of energy units that it can hold. Before the module repair, I was able to get 52kwh’s in the pack, still not great but we have gotten worse now maxing out of 47kwh after 2 full charges in a row, same result. Then as we approach the middle lower half of the pack, the car thinks it has way less energy left than it actually does due to the pack only being as good as its weakest cell. Ill show how much drivable range I got out of my 47Kwh’s at 100% SOC, according to the BMS, on the next slide.
Weak Cells!
The Results
I got very interesting results. The car at true leafspy SOC 28%, was flashing “---” 0 miles 0% state of charge in the vehicle. There was still 18kwh’s of capacity in the pack. That is another 72 miles at 4.0 kwh’s used per mile. I was able to drive past 0 until you see one of the cells got so low in voltage , turtle mode came on , and sitting at the charger completely dead , the car would not even shift into drive anymore , there was still 10kwh’s remaining in the battery. My 2015 leaf that I traded to you guys had healthy cells and could drive all the way down to 0.5kwh’s remaining. So from 100% to 0% , my usable capacity was 37kwhs and at roughly 3.7 kwh’s per mile, I was only able to drive 137 miles. That is a long way from a 56 - 58kwh usable driving range on a 62kwh pack that is rated at 226 miles. I understand battery degradation , this is far beyond that. 600mv difference from the lowest cell to the highest cell is dangerous, that is almost 1 entier volt difference, this will cause a unexpected shut down on the interstate.
The Results
So between the overcharged cells at the top of the back , and the weak defective cells at the bottom of the pack, I am unable to get anywhere near the usable capacity and range that I paid for in this vehicle. I paid for the long range S Plus model to be able to get that range. Let me know what you guys think, I would love to assist in getting this repaired because I do want to keep this car, it drives like a dream! It's just the battery issues making it almost un-drivable.
Thanks Guys!
Dawson Page