[EVeready]

Hi all,
I've just bought a second hand 2017 Zoe 41KW battery with 81000km. The seller recently has the battery SOH checked at Renault and was told it is 97%. I checked using the OBD2 & CANZE app, and it indicates 90% SOH.

Should I have the BMS updated? Which SOH figure should I go by?


Thanks in advance for any suggestions.

 

[Mo1]

Hi all,
I've just bought a second hand 2017 Zoe 41KW battery with 81000km. The seller recently has the battery SOH checked at Renault and was told it is 97%. I checked using the OBD2 & CANZE app, and it indicates 90% SOH.

Should I have the BMS updated? Which SOH figure should I go by?


Thanks in advance for any suggestions.

It was only the 22kW Zoe that had BMS issues needing updating (and looks like the ZE50 may too)
Was the car fully charged when you checked it? I found the SOC and ambient temperatures have an effect when checking SOH.

 

[EVeready]

The car was about 80% charged when I checked it. Ambient temp was about 2C

 

[X4dow]

updating the BMS will only change the way the same data is displayed. Your battery doesnt gain more capacity by changing the software which manages it. will just be updates to display the same old "90%SOH" as something else (95 for example)

 

[Rooster-x]

Its not very scientificic but a quick check would be to run down the battery to 20%, reset the GOM and then charge to 100% overnight. When our Zoe ZE40 R110 2018 model was brand new it had 186 miles of range, now its down to 168 miles with 30k miles on the clock. Unfortunately my ODII Dongle stopped working last year, but the SOH was 93% a year ago.

 

[X4dow]

GOM estimate is weather dependent too. I wouldnt guess my SOH from the GOM

 

[Dave Barr]

I have never seen my SOH fluctuate, as yet, on my 2017 ZE40 Q90. It only has went down. To be honest, it is the energy available that is my main concern. You should charge it to 100% and see what it says. Mine is 36 kWh at 100% with a SOH of 94. You can ignore the battery odometer as my car has down 27.5k miles, It has a battery fix at 3,800 miles and that has affected the battery odometer.

 

[Spike]

The available energy is low due to the battery temps. On our ZE40 I found a variation of around 3-4 kWh between a cold and a warm (above 20oC) one when using CanZE.

 

[Dave Barr]

The available energy is low due to the battery temps. On our ZE40 I found a variation of around 3-4 kWh between a cold and a warm (above 20oC) one when using CanZE.

That's true but mines never fluctuates by that much. High 37 kWh available when the battery is over 30C when rapid charging and the fans are going. When I first got it in Sep 2017 it was low 39 kWh and showing max range range of 168 miles. I find the available energy a better indicator of how the battery is doing than SOH. Although my battery is leased I don't think I'll ever get to the stage where Renault will replace it.

 

[ThudnBlundr]

updating the BMS will only change the way the same data is displayed. Your battery doesnt gain more capacity by changing the software which manages it. will just be updates to display the same old "90%SOH" as something else (95 for example)

That's strange, because when they updated the BMS on ours, the SOH went from 84% to 98%. You forget that the SOH reading is only an estimate calculated by the BMS using clever algorithms. They are designed to protect the battery from over-discharging. The only way to calculate the SOH exactly is to discharge each cell fully and see exactly how much energy it then takes to fill each cell to the maximum voltage, without wasting energy by balancing. That's non-trivial and would take considerable effort and time. That's why they created the BMS to estimate it instead.

 

[FlorianP]

I have never seen my SOH fluctuate, as yet, on my 2017 ZE40 Q90. It only has went down. To be honest, it is the energy available that is my main concern. You should charge it to 100% and see what it says. Mine is 36 kWh at 100% with a SOH of 94. You can ignore the battery odometer as my car has down 27.5k miles, It has a battery fix at 3,800 miles and that has affected the battery odometer.

View attachment 139462

Slightly higher figures @94soh here.

 

[Dave Barr]

Mines are lower through lack of use (2k miles in a year) and I rapid charged it heavily over year on a weekly commute to Derby. Monday 300 miles, Friday 300 miles. Two chargers per 300 mile trip.
Mine has just dropped to 93% at 28.2k miles (major under-usage) but max energy reads 36.5 at 19c battery average after 4 years.