Battery optimization

[Zelenec]

Technical "expert" at Citroen told me I should visit my dealer to do a battery optimization. He explained that every couple of years every c-zero should be connected to a tester, which needs about four hours to finish the process. He claimed that range and battery health should improve significantly after optimization. The most interesting part of what is going on during the optimization is repeating raising the cells voltage to 4,2V for a very short time. I hardly believe it should be good for battery since 4,2 is quite dangerous voltage for Li-Ion cells.

After 3 years and 83.000 km I notice about 15% of capacity drop so it sounds interesting to me.

Did anybody go through battery optimization and if so, what was the result?

 

[PV1]

Not sure if cycling the cells like that improve their life, but it would allow for resetting the capacity calculation, which could offer some range improvement.

4.2 volts isn't bad for the cells, but going above that isn't good. 4.2 volts is "fully charged", yet the jellybean (as I will now call the triplets, i-MiEV, C-Zero, and ion) only takes the cells to 4.11 volts. This alone gives us improved cycle life.

 

[Malm]

I think that will only result in a new capacity calculation, and only if the car is thinking that its capacity is less then it really is, the range will improve.

 

[Malm]

Technical "expert" at Citroen told me I should visit my dealer to do a battery optimization. He explained that every couple of years every c-zero should be connected to a tester, which needs about four hours to finish the process. He claimed that range and battery health should improve significantly after optimization. The most interesting part of what is going on during the optimization is repeating raising the cells voltage to 4,2V for a very short time. I hardly believe it should be good for battery since 4,2 is quite dangerous voltage for Li-Ion cells.

After 3 years and 83.000 km I notice about 15% of capacity drop so it sounds interesting to me.

Did anybody go through battery optimization and if so, what was the result?

I also notice a drop of about 15% of range. Mine now with 84.000 km and almost 5 years. Can you tell me how much it charges from 50% to 55%, seen by Canion? Mine charges about 540 Wh.

 

[Zelenec]

I also notice a drop of about 15% of range. Mine now with 84.000 km and almost 5 years. Can you tell me how much it charges from 50% to 55%, seen by Canion? Mine charges about 540 Wh.

I'l let you know but last time i measured this value, it was 62 Wh in average for 0,5 SoC so 50-55 620 Wh should go into the battery.

 

[Malm]

620 Wh is the most common value, I think. I think with a new one we should see that value. And in a new one the weakest cell will be around 3,5 / 3,6 V at 0,0% of SoC.

 

[Zelenec]

620 Wh is the most common value, I think. I think with a new one we should see that value. And in a new one the weakest cell will be around 3,5 / 3,6 V at 0,0% of SoC.

My friends C-Zero, year 2011, 14.000 km, averaged 148Wh per 1% SOC, so his value for 5% is 740Wh. I don't know about 50% SOC voltage, but I saw yesterday my car stopped at 8% SOC and many cells close to 2,8V. Really concerned... Any thoughts about that?

 

[Malm]

"My friends C-Zero, year 2011, 14.000 km, averaged 148Wh per 1% SOC, so his value for 5% is 740Wh." The value shouldn´t be so high. I presume the car had recalibrated is capacity for a value higher then the original one. Now, your friends car will stop not with weakest cells at 3,6 V, but at 2,75V.

 

[Malm]

"but I saw yesterday my car stopped at 8% SOC and many cells close to 2,8V. Really concerned... Any thoughts about that?"

Your car is doing many miles. That's what we should do with it. I suppose your car will have the battery many times at 30 ºC. So, one rate of degradation of 4%/year will be expected in your car. I-MiEV don´t recalibrate his capacity every day, takes time to do it. Sometimes if you stop with 50% SoC, after some time one bar will be not there. If he does that, it will stop with 3% SoC. But it will not count with that in the next charge. For me, your car is losing capacity with time (all cars will lose), but simply is thinking that hadn´t lost any. It will recalibrate, I don´t know when, so the best is going to someone who know to force him to do it. No problem at all with your car, just normal loss of capacity. In mine, before it recalibrated is capacity, I could stop with 14,5% SoC and 2,75 V in the weakest cell. Now goes to 0,0% SoC, like you all should know.

In conclusion, in my mind, no reason to be worried. I just see something that happened to me before, and now with almost 5 years driving it, 84.000 km, I never have been so happy with it. Just enjoy.