L3 Charging rates

[irfca]

While charging at a L3 charger this evening, I paid much closer attention to how long it took to charge, my start and end charge %, and computed the charging rate. It took 40 minutes to charge from 12% to 84%, so 72% of the battery capacity of 27 kWh, or 19.44kWh, and a charge rate of ~29 kW/h, well below the stated capacity of the L3 ABB charger I was at ... 50kW/h, and seemingly well below the rate Kia expected, from the time they indicated for charging (which I seem to think was around 25 minutes). Unfortunately, the Soul doesn't tell you anything about the rate is negotiated with the charger, so it is difficult to know why the rate was lower ...

What kind of charge rates have others been experiencing at L3 chargers?

 

[user 285]

Hmm, interesting. I've seen 50kW power on all three fast chargers I've used (100A x 500V) and the charge times have been as expected (short!). But the numbers were from the display on the charger, not from elapsed time and % SoC.

 

[tractioninc]

I've not made any measurements, but it has seemed to me that L3 charging toward 80% is very fast but the charging rate slows thereafter.

 

[JejuSoul]

I just charged from 22% to 82% in 35 minutes.
At the start the charger told me it would take 40 minutes.
In my experience the chargers always overestimate the time.

The advertising figures I see quoted for a 50 kW quick charger are that 12kw/h will take 20 minutes.
The actual battery capacity of a Kia Soul is 30kw/h. So I just charged 18kw/h in 35 minutes.
So my charging speed is only slightly slower than advertised.

The numbers shown on the charger display match those shown on the car.
Hence I was charged for 18kw/h.
Presumably there are efficiency losses during the charging.
I didn't think to look at the electricity meter nearby to find out what the actual figures are.

 

[irfca]

I charged at a new DCQC charger this afternoon (2nd public/non-dealer charger in Toronto!!), from 78% to 84% ... this was a much more sophisticated charger that showed the voltage and current ... 390vdc and it started at 125A and tapered down to 40A at 84%. This charger is only a few minutes from my work, and I only charged just to make sure I could, before I start to rely on it. I hope to use it a lot!

The estimated charge time was 4 minutes, and I believe it took about 4 minutes, maybe even a little less.

 

[JejuSoul]

Today I charged my car at a quick charger that was almost 50% faster.
I just charged from 22% to 80% in 22 minutes.
At the start the charger told me it would take 29 minutes.
This charger is adjacent to the one I wrote about a few days ago.

Some differences between the two chargers.
The faster one is two years old, and has two plugs. (nissan, renault)
It charges to a maximum of 80% and will not allow a top-up.

The slower one is a year old and has 3 plugs. (nissan, renault, bmw)
It charges to 83% and will allow a top-up to 87%.

 

[irfca]

I did a larger charge on the new Markham, ON DC quick charger last evening, and noted the kWh of charge and battery %. This time I was charging from 24% or 25%:

 %     % change     kWh      Proj Batter Capacity
65%      ~40%     11.3kWh    11.3/.4  = 28.25kWh ... charger started slow @122A, ~347vdc
75%      ~50%     14.0kWh    14.0/.5  = 28kWh    ... charger had increased to 124A-125A, ~ 380vdc
80%      ~55%     15.2kWh    15.2/.55 = 27.6kWh  ... charger tappering off to 80A, ~390vdc

According to the charger report, it took 20m55s to supply 15.4kWh ... I'm liking getting charging info back to know what was used! It would be kind of nice if the car could provide long term usage info like that ... cumulative power in to the charger, cumulate power consumed ... stuff like that.

 

[JejuSoul]

I assume "Proj Batter Capacity:" is the projected battery capacity of the car.
What meaning does the variation in the numbers have?
In the two charges I posted above the figures are
18/.6 = 30kWh
16.7/.58 = 28.8kWh
My range has remained normal. I doubt my battery capacity has actually decreased in a week.
Are some chargers really less accurate in their measurement of kw/h supplied than others?
I am not really interested in any cost saving for each individual charge, but care for the long-term health of the battery.

 

[irfca]

I was doing a simple projection ... I didn't take into account the 300w/h or so cooling overhead that occurs during charging. I also suspect that the apparent variability is more due to measurement error ... i.e. the estimated start point could be off by the range of ~1%, or ~0.277kWh, so the further the projection (eg from 40% vs from 60%), the larger the error is amplified.

 

[JejuSoul]

In future I will collect data for a month and average it out. This will reduce the measurement error. A comparison can then be made between say July 2015 and July 2016. I have the feeling that ambient temperature and humidity make quite a difference so it is probably best to compare like with like.