Experiences with APT Rapid Chargers
EV Drivers’ Usage Issues with Scotland’s Rapid Charger Network’s APT Chargers
Summary
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The Evolt APT Rapid chargers being deployed across Scotland as funded by Transport Scotland are
unfit for purpose as currently configured.
The legitimacy of the Rapid Charging Network being deployed by Transport Scotland is being
jeopardised by the APT Rapid chargers which do not meet specified outputs for a Rapid charger.
The Evolt APT Rapid chargers do not supply the specified rate of charging to either the AC output or
DC output.
The APT Rapid Chargers do not compare favourably to the Ecotricity network of Rapid Chargers.
A comparison of charging at an Evolt APT Rapid (43kW AC / 50kW DC) and Evolt APT Fast (22kW AC)
charger revealed that the Fast charger provides a faster charge rate than the Rapid charger.
A comparison of charging with both AC and DC outputs (using a Nissan Leaf and Renault ZOE)
revealed a very slow DC charge rate, and no difference to the slow AC charge rate.
Introduction
As a driver of a Renault ZOE who has undertaken a number of longer journeys from Aberdeen to Dundee and
Glasgow relying on the developing rapid charger network, it became clear to me that the APT Rapid chargers
were not functioning as expected in comparison to 22kW AC fast chargers and the Ecotricity “Electric
Highway” Rapid chargers.
In order to substantiate these observations, some comparison charges were undertaken using my own
Renault ZOE and the Nissan Leaf of a fellow EV driver.
The Renault ZOE uses AC charging and can accept rates up to the full 43kW that should be provided by rapid
chargers.
The Nissan Leaf can use both AC and DC. The AC is for standard charging, the Leaf uses the 50kW DC supply
for rapid charging.
When the slow rate of charge was identified, contact was initially made with Charge Your Car who advised
that the Renault ZOE will be at fault. The car was booked in with Mackie Motors, Brechin to be checked. No
faults were found with the car.
Charging Renault ZOE on Evolt APT Rapid Charger
For this evaluation the APT Rapid Charger at Gallowgate, Aberdeen was used. Its behaviour was the same as
that observed at the APT Rapid Charger at Greenmarket, Dundee and at Broxden, Perth.
The car began at a state of charge (SOC) of 9% on the battery. The charge was continued until 100%
completion. The final part of this charging process (above 90% SOC) is always much slower as the battery
nears a full charge. The relevant part of all the following charts is the period of maximum charge rate prior to
90% SOC.
Figure 1 (see below) shows the SOC against time. It is generally stated that a Rapid charger will charge a near
empty battery to 80% capacity in around 30 minutes (for AC on ZOE). This reveals it takes around an hour.
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Figure 1 State of Charge for ZOE on APT Rapid Charger
Figure 2 (see below) shows the energy provided by the charger (kWh) over time. From this we can calculate
a maximum charge rate of 17.8 kW. This is in contrast to the specified rate of 43 kW.
Figure 2 kWh Provided by APT Rapid Charger
The charts make it clear that the APT Rapid Chargers are not providing the AC output expected.
It should be noted that no other car was connected to the APT Rapid Charger at the time. The temperature
was around 4C, which has been about the same for all the charges recorded. The car had just driven some 30
miles, so the battery would not have been cold at the time of charging.
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Comparison with Ecotricity Rapid Chargers
On the four occasions that Ecotricity Rapid Chargers (also rated at 43kW AC / 50kW DC) have been used with
my Renault ZOE I noticed that the charging was considerably quicker. One full charge from 3% to 100% SOC
took a little over an hour, for instance. This is what is expected from a Rapid Charger.
As I do not live near to an Ecotricity charger, it has not been possible for me to carry out the same evaluation
of charge rate as has been possible with the APT Rapid Chargers, but a fellow Renault ZOE driver in England
did this in response to some of the questions raised about differing charge rates.
He kindly has allowed me to use the chart he created from the data he recorded from one journey of over
300 miles in which he used five different Ecotricity Rapid Chargers.
Figure 3 SOC of Renault ZOE using Ecotricity Rapid Chargers
During the maximum charge rate the Ecotricity Rapid Charger is providing around 40kW. The car charged
from 20% SOC to 90% in 25 minutes, repeatedly. From the data and experience I have gained, this would
take about an hour with an APT Rapid Charger.
The Ecotricity Rapid Chargers appear to be working to specification, the APT Rapid Chargers are not.
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Comparison Charges at Aberdeen City Rapid and Fast Chargers
As Aberdeen has both Rapid and Fast chargers provided by APT, a comparison between the two was also
conducted using the previous data and by charging at the Evolt APT Fast Charger (22kW AC) in Frederick
Street Car Park.
The State of Charge on the battery was 20% at the start of charging on the Fast charger at Frederick Street.
To help comparison purposes, the timing of the charge at Frederick Street has been shifted to begin ten
minutes later on the chart to allow an easier comparison so that it begins around the time the comparison
rapid charge at Gallowgate had hit 20%.
Figure 4 shows the comparison of SOC against time. It is clear from the chart that the “slower” 22kW charger
is in reality providing a significantly faster charging rate than the “faster” 43kW rapid charger.
Comparison of CYC Evolt APT 43kW "Rapid" and
22kW "Fast" AC Chargers with Renault ZOE
State of Charge vs Time
00:00
00:05
00:10
00:15
00:20
00:25
00:30
00:35
00:40
00:45
00:50
00:55
01:00
01:05
01:10
01:15
01:20
01:25
01:30
01:35
01:40
01:45
01:50
01:53
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
SOC (43kW)
SOC (22kW)
Figure 4 Comparison Charges with Renault ZOE on APT Rapid and Fast Chargers
Again, the long period in the charts when the battery is carrying out cell-balancing and conditioning is not
important. The important part is the charging rate up to around 90% battery capacity.
When using the Rapid charging network one would not normally wait until 100% capacity, but, in the case of
the ZOE would disconnect and continue the journey at around 90% capacity when the charging rate begins
to slow down.
Figure 5 (see below) shows energy (kWh) provided by the chargers for each charge. Note that the two
charges started at different SOC on the battery so the maximum amount of energy provided is not the
comparison. The comparison is of the maximum charge rates in the first part of the chart.
This chart clearly shows the different charging rates during fastest charging, with the 43kW Rapid charger
only providing 17.8 kW, whereas the 22kW Fast charger provides 20.9 kW. The Fast 22kW charger is close to
providing the specified output.
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Comparison of CYC Evolt APT 43kW "Rapid" and
22kW "Fast" AC Chargers to Renault ZOE
kW Provided vs Time
25
20
15
10
5
kW (43kW)
01:53
01:50
01:45
01:40
01:35
01:30
01:25
01:20
01:15
01:10
01:05
01:00
00:55
00:50
00:45
00:40
00:35
00:30
00:25
00:20
00:15
00:10
00:05
00:00
0
kW (22kW)
Figure 5 kWh Provided by APT Rapid and Fast Chargers to Renault ZOE
There is clearly something awry with the setup of the Rapid chargers when the Fast charger is providing a
clearly identifiable quicker charge rate.
Charging with both Renault ZOE and Nissan Leaf at APT Rapid Charger
There is speculation that the APT Rapid Chargers have been set up in such a way that if two cars are charging
at the same time using both the AC and DC outputs that the output is halved to each car.
To test what would happen with both outputs functioning, I and a fellow EV driver tried this at the
Gallowgate, Aberdeen APT Rapid Charger.
The ZOE began at a SOC of 13%, the Nissan Leaf had two bars remaining (it does not provide SOC
information) which we estimated at between 30% and 40% SOC. The Leaf was connected first and allowed to
start charging, then the ZOE was connected, around a minute or two later.
The Nissan Leaf reached 80% SOC in 52 minutes at which time the DC side of the charger stopped as it is
designed to do, 10.8 kWh of energy had been provided by the charger over this time.
The Renault ZOE does not have a limit on the charging defined by the charger so was allowed to continue to
99% with a total of 19.62 kWh of energy provided.
Figure 6 charts the energy provided to both cars over time. Note that the chart shows the Leaf starting
slightly ahead, this is because it had the advantage of an extra 90 seconds or so of charging time.
What this revealed is that the AC side operated very similarly to how it operates when only one car is
attached, the charge rate being around 17.6 kW.
What it also shows, however, is that the DC side is operating far below the specified rate, even taking into
account that the charger may halve output when two cars are connected (though there is very little
difference recorded to the AC output). The charge rate for the Leaf from the 30 minute period in the middle
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of the charge was 11 kW. This is in contrast to the specified full rate of 50kW or 25kW if the output is halved
when two cars are connected.
Figure 6 Charging both Renault ZOE and Nissan Leaf at APT Rapid Charger
Comments
The evidence provided in this document reveals that the APT Rapid Chargers are not working as specified
and certainly have no part in a Rapid Charging infrastructure as currently configured.
It is hoped that this evidence will help to remedy this situation.
The presence of a Rapid Charging Network is vital for further adoption of EVs, this needs to be resolved
quickly in order to assist this adoption, and to represent good stewardship of the public purse funding these
APT Rapid Chargers.
If any further information is required, I will be happy to provide it or to talk to anyone about these
experiences in order to facilitate resolution of these matters.
Rev Peter Johnston
27 February 2014
54 Polmuir Road
Aberdeen
AB11 7RT
Home: 01224 949192
Mobile: 0783 428 1176
Email: [email protected]
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