poor charging efficiency

[shweeney]

charged our ZS (standard range) last night - according to the charger we used 28.7kWh over the 4 hours we have cheap electricity.
On the car battery this translated to +36% which by my calculation is 18.4kWh.

So only 64% of the power went into the battery, this seems really poor as I would expect no more than 15% conversion losses. It wasn't a particularly cold last night (maybe 10C) - any ideas?

 

[Catsailor]

Similar experience with my Long Range ZS. After a charge to 100% the GOM said only 247 miles range instead of 273. The next dayafter an 80% charge the GOM said only 198 miles which, pro rata is the same loss of 10%. I have asked for a battery dtate of health check which the gargae have said they will do but they also said "Please be reassured that variations in the indicated range are quite normal at this time of year, as colder weather typically reduces the displayed mileage due to the additional energy required for battery conditioning and cabin heating. This does not necessarily indicate any loss of battery performance, and those estimations will likely improve again as we get into Spring next year."
I will post an update of the Sate of Health check.

 

[Jomarkh]

charged our ZS (standard range) last night - according to the charger we used 28.7kWh over the 4 hours we have cheap electricity.
On the car battery this translated to +36% which by my calculation is 18.4kWh.

So only 64% of the power went into the battery, this seems really poor as I would expect no more than 15% conversion losses. It wasn't a particularly cold last night (maybe 10C) - any ideas?

That is quite a loss. Are you using actual 'usable' battery size?

 

[shweeney]

Similar experience with my Long Range ZS. After a charge to 100% the GOM said only 247 miles range instead of 273. The next dayafter an 80% charge the GOM said only 198 miles which, pro rata is the same loss of 10%. I have asked for a battery dtate of health check which the gargae have said they will do but they also said "Please be reassured that variations in the indicated range are quite normal at this time of year, as colder weather typically reduces the displayed mileage due to the additional energy required for battery conditioning and cabin heating. This does not necessarily indicate any loss of battery performance, and those estimations will likely improve again as we get into Spring next year."
I will post an update of the Sate of Health check.

the range is just an estimate. Our battery health was at 97% when it was last serviced (2023 car). My issue is that 28kWh of electricity only took the battery from 32% to 68% - the percentage is not an estimate.

That is quite a loss. Are you using actual 'usable' battery size?

it's 51kWh total with 49kWh usable so whichever you use, it's still bad.

 

[Everest]

Doesn't sound right to me. Have you checked...
a) that you didn't select any cabin pre-conditioning to be on?
b) that your smart meter's night-time usage concurs with what your charger reported it used?
- and, if you're old, like me -
c) that you had your glasses on and didn't misread the 32% as 22% or even read 88% as 68% ? !

 

[shweeney]

Doesn't sound right to me. Have you checked...
a) that you didn't select any cabin pre-conditioning to be on?
b) that your smart meter's night-time usage concurs with what your charger reported it used?
- and, if you're old, like me -
c) that you had your glasses on and didn't misread the 32% as 22% or even read 88% as 68% ? !

it was definitely 32% before and is 68% now. No reason to think the charger is mis-reporting, it was set to charge for 4 hours and that's exactly how much kWh I would expect it to use. It's possible I suppose that the car could be mis-reporting the SOC.

 

[Catsailor]

Similar experience with my Long Range ZS. After a charge to 100% the GOM said only 247 miles range instead of 273. The next dayafter an 80% charge the GOM said only 198 miles which, pro rata is the same loss of 10%. I have asked for a battery dtate of health check which the gargae have said they will do but they also said "Please be reassured that variations in the indicated range are quite normal at this time of year, as colder weather typically reduces the displayed mileage due to the additional energy required for battery conditioning and cabin heating. This does not necessarily indicate any loss of battery performance, and those estimations will likely improve again as we get into Spring next year."
I will post an update of the Sate of Health check.

Battery State of Health: 100%,


Explains something to me but not your issue.

 

[Jto]

Have done a reset of acclimated trip? And is it reading 100% of charge and what is the range

 

[Catsailor]

I notice that my range has gone up in the milder weather of the last few days

 

[Jomarkh]

I notice that my range has gone up in the milder weather of the last few days

You will see a 30% drop between the summer and winter

 

[Catsailor]

You will see a 30% drop between the summer and winter

I expected a drop in range. What I did not expect was that car would estimate the range reduction. Is it calculating that based on the time of the year or actually using the ambient temperature in its calculation?

 

[SteveM]

Just for fun, because I charged the night before last, and because I was curious to check the process described: I took an MG4 LR battery (64kWh nominal) from around 15 - 85 % (I might have misremembered by 1 or 2%). My Evec charger app reports 49.77kWh. By my reckoning, that is an efficiency around 90%, a little better than I expected.

I guess you are relying on the vehicle battery "gauge", presumably working from the modest voltage change during discharge. Were you at one extreme or the other? e.g. were you going from 64% to 100% or 0 to 36%?

 

[Catsailor]

64 - 100.

 

[Everest]

I guess you are relying on the vehicle battery "gauge", presumably working from the modest voltage change during discharge.

No... BMS's normally use coulomb counters to calculate change in charge levels. They only use voltage to reset/recalibrate to 100% when a full charge results in cells or the pack reaching a pre-defined maximum voltage.

You can't use voltage as a measure of state of charge because, as you say, the voltage change is modest (esp. with LFP-based vehicles) - voltage is also hugely affected by the power being drawn / put into the battery pack.