Battery degradation

[fsimao222]

Hello,
In the last months I’ve noticed that my MY17 was doing substantially less kms.
It was winter time so I thought it could be normal.

Today with 23°c I decided to make a test.

I traveled in a flat road 80km/h until the battery was empty.

I traveled a total of 39km and the electric consumption was 16,2kWh.

Ive done some calculations that I want you to check if they are correct, because I got 32% degradation in less than 2 years.
Maybe I’ve not calculated it correctly.

Thanks.

 

[jaapv]

I'm not sure that you can calculate battery state of health like this. You should have the official measurement at delivery and one now. Mitsubishi can provide those.

 

[Trex]

Hello,
In the last months I’ve noticed that my MY17 was doing substantially less kms.
It was winter time so I thought it could be normal.

Today with 23°c I decided to make a test.

I traveled in a flat road 80km/h until the battery was empty.

I traveled a total of 39km and the electric consumption was 16,2kWh.

Ive done some calculations that I want you to check if they are correct, because I got 32% degradation in less than 2 years.
Maybe I’ve not calculated it correctly.

Thanks.

Hello fsimao222,

There is approx 8.4 kWh usable capacity on the older PHEVs available when new ie 100% - 30% (unusable capacity) = 70% = .7 X 12.0 kWh = 8.4 kWh

 

[greendwarf]

39km equates to 24 miles - about what I am getting from my 2014 car with 36,000 miles (58,000km), so not too bad. What we don't know is your mileage and what you were getting on battery before to be able to take a view on your figures.

 

[jaapv]

Well, it depends on the circumstances. Distance driven is not a valid parameter. I can get 37 km from my 2013-2014 car with 120.000 km if I drive very carefully at 20ºC in optimal road conditions, but something around 30 km is more usual.

 

[fsimao222]

I used to do 51km in the same road last summer. around the same speed.

It now have 43000km.

39km equates to 24 miles - about what I am getting from my 2014 car with 36,000 miles (58,000km), so not too bad. What we don't know is your mileage and what you were getting on battery before to be able to take a view on your figures.

 

[fsimao222]

It was optimal road conditions. Flat road, 23ºc, always at same speed.
I'll try tonight to add a meter in the plug to measure the total kWh charged with empty battery. maybe its more accurate?

Well, it depends on the circumstances. Distance driven is not a valid parameter. I can get 37 km from my 2013-2014 car with 120.000 km if I drive very carefully at 20ºC in optimal road conditions, but something around 30 km is more usual.

 

[fsimao222]

Yes, you are right, I've made 12/1.3, that's why I get 9.23kWh
Thanks

Hello fsimao222,

There is approx 8.4 kWh usable capacity on the older PHEVs available when new ie 100% - 30% (unusable capacity) = 70% = .7 X 12.0 kWh = 8.4 kWh

 

[jaapv]

It was optimal road conditions. Flat road, 23ºc, always at same speed.
I'll try tonight to add a meter in the plug to measure the total kWh charged with empty battery. maybe its more accurate?

Well, it depends on the circumstances. Distance driven is not a valid parameter. I can get 37 km from my 2013-2014 car with 120.000 km if I drive very carefully at 20ºC in optimal road conditions, but something around 30 km is more usual.

That is certainly more accurate, but still not very precise. The "full" value will be fairly constant, but there is no way of telling how deeply the battery has been depleted, as the car software has a number of different cut-off points. For instance, if the battery is registered empty and the car in hybrid mode at about 27%, the car can still pull power under full load, down to 20% aprox. To get to the absolute lowest level (15% IIRC), you have to force it into Turtle Mode.
The best way is to request the battery condition reports from your dealer, both the original delivery one (which will always be lower than the nominal value) and a recent one.

 

[greendwarf]

It was optimal road conditions. Flat road, 23ºc, always at same speed.
I'll try tonight to add a meter in the plug to measure the total kWh charged with empty battery. maybe its more accurate?

Well, it depends on the circumstances. Distance driven is not a valid parameter. I can get 37 km from my 2013-2014 car with 120.000 km if I drive very carefully at 20ºC in optimal road conditions, but something around 30 km is more usual.

I agree but a high mileage car is likely to show more "wear & tear" than a low one - and the PHEV is no different. If the OP is saying it has dropped from 51 to 39km over winter with a relative low overall usage then that would raise doubts about his battery. However, it might be that he has been "canning it" in the last few months with a different driving/charging pattern that has "aged" the battery more quickly - only he will know.

But at the end of the day 39km doesn't seem an unrealistic range for his car, if it doesn't continue to fall significantly.

 

[Mike01Hu]

There seems to be so much misunderstanding of battery performance. SOC depends on too many variables for the individual to totally control and it is unreasonable to expect the same performance day to day. The driver has the greatest inadvertent influence, such a variations in the rate at which acceleration or braking is applied, particularly at the start of hills, up or down, who or what they carry in the vehicle, heating or cooling applied and rate of cornering etc. Relatively small changes in temperature during charging and discharging will affect SOC even though the BMS does its best to mitigate the changes. I am not surprised at the changes but do feel that there is a flaw in the BMS software in that it is not managing the SOH effectively but it does not mean there is abnormal battery degradation. My experience as an electronics engineer in managing Ni and Pb battery management points in this direction but my expertise did not extend to LiPo cells.

 

[HHL]

There seems to be so much misunderstanding of battery performance. SOC depends on too many variables for the individual to totally control and it is unreasonable to expect the same performance day to day. The driver has the greatest inadvertent influence, such a variations in the rate at which acceleration or braking is applied, particularly at the start of hills, up or down, who or what they carry in the vehicle, heating or cooling applied and rate of cornering etc. Relatively small changes in temperature during charging and discharging will affect SOC even though the BMS does its best to mitigate the changes. I am not surprised at the changes but do feel that there is a flaw in the BMS software in that it is not managing the SOH effectively but it does not mean there is abnormal battery degradation. My experience as an electronics engineer in managing Ni and Pb battery management points in this direction but my expertise did not extend to LiPo cells.

There seems to be a refusal to accept that batteries do in fact degrade.....

 

[elm70]

It is already difficult to estimate properly battery degradation with the OBD2 WatchDog .. so in absence of this, is almost impossible to give any realistic idea what is going on.

Real EV range from fully charged is influenced not only by the driving style, but as well, by the temperature of air and of the battery, and as well .. it even matter how many hours before the car did finish the charging process.

What I recently notice on my PHEV is that the voltage per cell when the battery has almost 0 EV range .. so close to 30% real SOC ... it is now around 3.85v .. while 1 year (or more) ago it was around 3.82v

Since my PHEV now assume 30% SOC at 3.85v per cell, it is looking the SOH is going to be reduced massively by the BMU since clearly 3.85v per cell is way more ... so with battery aging, the already huge 30% buffer on low state of charge, it is even expanding.

I'm wondering if this is a common patter ... if more and more people notice that voltage per cell at ~30% SOC is going up ... it can explain why the BMU reduce the SOH more as we expect

Clearly .. voltage per cell .. need to be measure after 2h from last usage, and without charging the car ... the cell voltage while used and short after car usage, it can be much lower then after 2h of rest

PS: I also notice that the keyfob hack for activate the cabin heat, often is not recognized by the BMU ... so if I use the keyfob hack after the car is charged , while the car is not connected ... the BMU can detect that available capacity is much less then expected only after usage ... so ... it has possibly an impact on downgrade the SOH ... as opposite ... if keyfob hack is used in the middle of the charging process , the BMU will believe that the battery can get more charge then what expected.

 

[ThudnBlundr]

@Mike01Hu - I think you're confusing SOH and SOC

 

[Klausm]

Elm

You are writing "keyfob hack for activate the cabin heat" can you please tell me about that or if you have a link, please.

Thanks

 

[Regulo]

Try this one: http://www.myoutlanderphev.com/forum/viewtopic.php?f=11&t=2118&hilit=remote+key+fob