Umbau Fluence auf 30kWh Leaf-Akkus

[alameda25]

I have finished connecting all the new battery cells to the BMS, and tried to communicate to it with my OBD, with no success. Same symptoms that before connecting the cells. I measured the BMS current with a sensitive ammeter, and the BMS drained 1,2 mA. It seems the BMS gets the 12V supply, but remains in standby. I closed the interlock pins of the external fuse, but I didn't dare to connect the interlock pins of the power connector. I will mount the battery pack into the car, and we’ll see!

[alameda25]

Hi, my Fluence is running again. Thanks Andreas for your ideas and support; without them my project never would have succeeded.

I have lately learned a couple of things I would like to share:
- It is not feasible to communicate with the battery disconnected from the car because the car's EVC (the ECU of the ZE) is itself another interlock. While a was mounting the battery in the car, I disconnected one of the switches sensing that the T locks are in closed position, and the battery was not detected by the car and the OBD. Those switches go to the EVC.
- The later is a pity. The batteries are still charging but it seems there is a cell 150-170 mV lower that the other 95 cells. It could be due to I charged and discharged one battery for testing when I received the full batch of batteries. I tried to left the same charge that the other ones, but it seems I did it wrong. As all the cells charge and discharge in series, I am not sure if the BMS shall be able to equilibrate a single cell with a low voltage. I read that the BMS can discharge single cells (of lower capacity that charge faster) with higher voltages; but should the BMS able to apply extra charge to a single cell?

I am happy for the work done, and seeing the car running. But an issue still remains. As the old batteries were below the 50% SoH, the car considered they were faulty and limited the power of the car as a safety mode; with the new batteries it remains. Andreas described that the SoH was increasing after several charge cycles. I hope that when my SoH improve enough the car will return from the safety mode to the normal mode, and that it will not remain in the safety mode forever. Should it be a way to reset the memory of the BMS or EVC telling them they have new batteries?

[lukasgo]

Hello!

BMS will reset its values in time and you will gain SOH measure.

I changed my 2013 24kWh cells (SOH 58%) for 2016 Nissan Leaf 24 kWh cells (SOH 82%) and just after the first charge I got 60% which after approx. 3 weeks went up to 90-91% and still stays there after 5000km.

Which battery modules did you use for the upgrade?

Mvg
Łukasz

[alameda25]

Last end: The issue was not an undercharged cell, but a defective one. When I tried to charge it, it did not take any charge. My initial confusion was due to Fluence Spy showed the cell discharging and charging with the other cells, and "just" with a lower voltage of 150 mV at full charge, and 60 mV when discharged.

Fortunately, St. Murphy was good to me; I had an spare cell, the cell was located in the upper box of the pack, at one side of the box, the easiest to extract it. The full operation took me 3 hours (after several mounts/dismounts of the battery it seems a child's play). Now it seems everything is ok. After the first full charge the SoH has increased from 48% to 55%, exiting from the safety mode with the limited power. And as you say, it is quite probable to reach the 65% very soon. I will be happy recovering the beloved cruise control.

Batteries show real 40 Kwh capacity, and resetting the Consumption indicator after each full charge, a precise range estimation shall be easy to be done. The only annoying issue will be the empty alarm when the car had consumed quite less that 50% of the real capacity. Any idea to suppress that alarm?

[Andi42]

Congratulations for your mod and that there is another Fluence still running

What I did for the alarm is to reduce the measured current for the BMS. But this does not affect heating and AC. So without heating and AC the reange is quite good and the alarm does not go on too early. In winter however, heating power, that is measured separately, makes the car think, that the battery is empty too early.

Cheers
Andreas

[alameda25]

Thanks Andreas. I will try to locate the alarm buzzer and try to moderate or eliminate the warning sound. I would like to do more ambitious trips with my new batteries.

[E-Dani]

Hello Igor,

congratulations for your retrofit!
If you have located the buzzer let us know where it is and how you have sooved it. It's really annoying this beeping.
I also have not noticed, whitch cells you used in your rebuild battery. Is this a secrect?
kind regards
Daniel

[alameda25]

Hi. I still have not disassembled tthe instrument panel where I think the buzzer is located.

There are several vendors of the cells at Alibaba. Search for "CATL116Ah 3.6v NMC rechargeable prismatic cell", or directly go to "https://www.alibaba.com/product-detail/ ... pR1aDb&s=p"

[alameda25]

Hello. I have just removed the instrument panel and it's surprisingly easy to do. I had never imagined that it could be done simply with the hands. There are tutorials on YouTube explaining it. And indeed, the buzzer is on the PCB of the panel. It is a small speaker (300 ohms), common to all the sounds of indicators and warnings of the car. From the beginning I ruled out canceling it completely. I tried to put a volume potentiometer, but the ones I had on hand don't fit in the small free-space on the panel. The other two solutions were to permanently dim it to a tolerable volume, but tolerable for me resulted to be zero. So I have finally installed an ON/OFF switch to disconnect it only when the alarm starts that remember me that I only have 23 Kwh left. I attach some photos.

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[alameda25]

Latest findings. It seems that the CATL batteries are doing well: No battery heating, and excellent measured capacity. As Andreas pointed out in previous posts, when a Fluence receives new 40 Kwh batteries there is an issue due to the mismatch between the real capacity and the capacity “perceived” by the car. According to the Fluence Spy the car consider that my batteries now are in the following condition (that changes after every new charging cycle):
- SoH: 103%
- Maximum capacity: 19,4 Kwh
- IR: 85 mohm (I do not like this figure, but it is coherent with the IR I measured during the cell tests; I think the fresh original batteries measured a quite lower value).
Due to this, the driving range seems to be limited the following way (as I saw it during a deep discharge, after not charging for 3 days):
- When the real consumption reaches the 17-18 Kwh figure, Fluence Spy shows <5% of remaining capacity and the recharging alarm sounds continuously. I used the muting switch I have installed in the instrument panel. Figures are not exact as I was not able to monitoring Fluence Spy continuously.
- When the real consumption reached 27-28 Kwh and Fluence Spy showed < 2% of remaining capacity, the car activated a Limited Performance state of 20 Kwh. After several months driving in this mode by familiar routes it was a minor issue for me.
- And finally, when the real consumption was about 32 Kwh and Fluence Spy showed less than 1% of remaining capacity, the car activated a Limited Performance state of 16 Kwh. This is a serious issue; the car cannot continue running at acceptable speeds. This state was hold during 5-6 km, even with an indication of 0,00% remaining capacity!
I do not expect these figures would improve in the future, even if the SoH continued increasing. It is a pity being noy able to squeeze the last 25% of the real capacity of the batteries (but good for their health), but I am happy having a real 30 Kwh Fluence with a real range of 200 Km.