DCFC - Slower than expected - 2018 SV

[knightmb]

Nominal 50 kW EvGo yesterday maintained 44 kW all the way from 10% to 80%, and cost $21.50 or about $.50 per kWh. A ripoff as far as cost goes but what are the options on the road.....

Blink is the same way in my area, high cost per time instead of actual power. Having my 2020 to test DCFC this year has shown me that I wasn't just seeing things in my 2013 vs. the fast chargers in my area. They all start out fast but the ramp down can be insanely slow towards the end. The free QC at Nissan HQ (and EA QC) showed me that other QC networks could be a whole lot faster and it's not always the EV that is the limiting factor.

I can put 200 miles of range on my Leaf for only $7 and 30 minutes with an EA network, to the do the same thing on Blink cost roughly +$32 now and takes nearly an hour. Now all QC networks are created equal unfortunately.

 

[SageBrush]

I can put 200 miles of range on my Leaf for only $7 and 30 minutes with an EA network

I don't expect that to last, but it is true that those states with 12¢ per min cost up to 90 kW with a $4 per month pass get a fantastic deal.

Is it true that EA sets the tier by the car's peak kW capability rather than the peak kW during the charging session ?

 

[knightmb]

Is it true that EA sets the tier by the car's peak kW capability rather than the peak kW during the charging session ?

EA (in my area, it may vary in others) they charge $0.16 / minute for any rate under 90kW and $0.32 / minute for all others above. There is also a fee to start the session, which is $1 I think, so 30 minutes of Leaf charging comes out to roughly $4.80 plus the $1 fee (and some taxes somewhere), so it ends up being a little over $7.xx cost. If the Leaf is the 62 kWh battery and the SOC level was very low, you can expect nearly full 50kW rate during the entire 30 minute session which can easily get you up to +200 miles of range. The EA in my area are very aggressive on the fast charge, they do ramp down as you get past 80% SOC, but down to the 25kw-30kW range, not 8kW like a lot of the other networks do. :?

 

[SageBrush]

Is it true that EA sets the tier by the car's peak kW capability rather than the peak kW during the charging session ?

EA (in my area, it may vary in others) they charge $0.16 / minute for any rate under 90kW and $0.32 / minute for all others above. There is also a fee to start the session, which is $1 I think, so 30 minutes of Leaf charging comes out to roughly $4.80 plus the $1 fee (and some taxes somewhere), so it ends up being a little over $7.xx cost. If the Leaf is the 62 kWh battery and the SOC level was very low, you can expect nearly full 50kW rate during the entire 30 minute session which can easily get you up to +200 miles of range. The EA in my area are very aggressive on the fast charge, they do ramp down as you get past 80% SOC, but down to the 25kw-30kW range, not 8kW like a lot of the other networks do. :?

Perhaps examples would help.

1. You show up with a Tesla that is rated up to 250 kW. It starts to charge at 247 kW and tapers down to 80 kW

2. You show up with a Tesla that is rated up to 250 kW. It starts at 80 kW and tapers down to 20 kW

Are both cases the same high tariff, or does the (2) example get the lower tariff ?

 

[Snargleblarg]

If the Leaf is the 62 kWh battery and the SOC level was very low, you can expect nearly full 50kW rate during the entire 30 minute session which can easily get you up to +200 miles of range.

The math isn't working for me. 30 minutes at 50kW would put 25kWh into the Leaf. At 4 mi/kWh this comes out to +100 miles of range. How are you getting +200 miles added in 30 minutes on a 50kW charger?

 

[knightmb]

If the Leaf is the 62 kWh battery and the SOC level was very low, you can expect nearly full 50kW rate during the entire 30 minute session which can easily get you up to +200 miles of range.

The math isn't working for me. 30 minutes at 50kW would put 25kWh into the Leaf. At 4 mi/kWh this comes out to +100 miles of range. How are you getting +200 miles added in 30 minutes on a 50kW charger?

You are right, I phrased the information badly. The EA QC here will run the ChaDeMo up to 75 kW but that will ramp down quickly to the 50 kW range. Also, I should have stated this wasn't from 0% SOC.

The more technically correct statement would be "If the Leaf is the 62 kWh battery and the SOC is in the 20% range, you can expect nearly full 50kW rate after the 75kW ramp-down during the entire 30 minute session which can easily get you up to 80% SOC and a range of +200 miles, not an extra 200 miles added to the battery."

 

[knightmb]

Perhaps examples would help.

1. You show up with a Tesla that is rated up to 250 kW. It starts to charge at 247 kW and tapers down to 80 kW

2. You show up with a Tesla that is rated up to 250 kW. It starts at 80 kW and tapers down to 20 kW

Are both cases the same high tariff, or does the (2) example get the lower tariff ?

I understand now, unfortunately I don't have a Tesla to test with. My logic would say the rate should get cheaper once the Tesla gets under 90kW of power, but if I happen to come upon one charging, I'll ask the owner about the rate and payment structure for them.

 

[illidotane]

I've had the chance to do a proper DCFC lately and ended up with two nice graphs, from the charger and from LeafSpy. I had the car in ACC mode so that LeafSpy would record continuously. Care was taken to do exactly nothing otherwise (no heating, no nothing, just ACC mode).

Alternate graph from website:

Battery was cold at the start (38°F, 3.3°C) as per the logs; I don't know why the black curve doesn't match this. Temp at the end was 82°F, 28°C which matches the graph.

The amperage was limited at the beginning as expected due to the low temperature. We can clearly see the current increasing in steps as it becomes warmer. As per log files:
Initial: 100A | Max: 38.2°F min: 35.5°F avg: 37.3°F (max: 3.4°C min: 20.7°C avg: 2.9°C)
Increase to 105A | Max: 40.0°F min: 37.1°F avg: 39.0°F (max: 4.4°C min: 2.8°C avg: 3.9°C)
Increase to 112.5A | Max: 42.0°F min: 39.1°F avg: 41.0°F (max: 5.6°C min: 3.9°C avg: 5.0°C)
Increase to 120A | Max: 43.8°F min: 40.5°F avg: 42.6°F (max: 6.6°C min: 4.7°C avg: 5.9°C)
And then decrease from 120A as per graph: Max: 46.2°F min: 42.7°F avg: 44.9°F (max: 7.9°C min: 5.9°C avg: 7.2°C)

The charger was from Electric Circuit network (AddÉnergie, 100kW and 200A CHAdeMO).

I have no idea why the car would do this. It doesn't seem to be a glitch, i.e. the decline has a visible exponential decay at first then linear. Hence why at this point I'm lead to believe it's the charger controller, but I wouldn't know why.

 

[illidotane]

Well, would you look at that. I wrote to Electric Circuit regarding the odd charging speeds that I've experienced and provided the sessions reference numbers and they've responded the following:

Hello,
Thank you for your interest in the Electric Circuit.

In answer to your message, after verification, both [CHARGER #1] and [CHARGER #2] charging stations were indeed not functioning properly at the time you used them. Many users were unable to charge their vehicle at those stations and reported the issue.

Please note that your request has been transferred to the appropriate department. You should therefore receive an answer from them shortly.

Please do not hesitate to write to us again should you have any other questions or comments.

Best regards,

It appears to have been the chargers then. I'll copy here whatever information they follow-up with.

As knightmb said...

I can say for certain that not all DCFC are created equal.

 

[SageBrush]

The more technically correct statement would be "If the Leaf is the 62 kWh battery and the SOC is in the 20% range, you can expect nearly full 50kW rate after the 75kW ramp-down during the entire 30 minute session which can easily get you up to 80% SOC and a range of +200 miles, not an extra 200 miles added to the battery."

I think you are saying that a 30 minute DC charge at a 'good' location will bump your 62 kWh LEAF up 55% -- from 25% to 80% SoC.
That is perhaps 55 * 0.55 = 30 kWh in 30 minutes, so about 60 kW average

Compared to my 24 kWh LEAF from 2013, that is easily twice the power, but compared to modern EVs it is about 1/2 the power. I think that the upcoming Tesla EVs will take 30 kWh in 10 minutes during their best case SoC interval.

 

[SageBrush]

Since the BLINK chargers are able to output ~ 120 Amps but do not continue to do so even though the car is able to take the current, it may be that the charger itself has a taper, perhaps temperature related.

I admit to being influenced by a bias I hold that BLINK is sub-par quality. Or it may be that maintenance at BLINK stations is inadequate, leading to cooling issues.

 

[WetEV]

Compared to my 24 kWh LEAF from 2013, that is easily twice the power, but compared to modern EVs it is about 1/2 the power. I think that the upcoming Tesla EVs will take 30 kWh in 10 minutes during their best case SoC interval.

That's just 180kW, shouldn't be a problem for any higher end upcoming EV. My old 2019 e-tron can take over 145kW for 50kWh. The Porsche Taycan can do 250kW for 28kWh. Lucid Air is even faster.

 

[SageBrush]

Compared to my 24 kWh LEAF from 2013, that is easily twice the power, but compared to modern EVs it is about 1/2 the power. I think that the upcoming Tesla EVs will take 30 kWh in 10 minutes during their best case SoC interval.

That's just 180kW, shouldn't be a problem for any higher end upcoming EV. My old 2019 e-tron can take over 145kW for 50kWh. The Porsche Taycan can do 250kW for 28kWh. Lucid Air is even faster.

I should have added that I was thinking of the 82 kWh packs put in the Tesla Model 3/Y. Larger packs do better, all else being equal.

 

[illidotane]

Since the BLINK chargers are able to output ~ 120 Amps but do not continue to do so even though the car is able to take the current, it may be that the charger itself has a taper, perhaps temperature related.

This is making me realize that this could very well be an issue whenever we get unexpected slow charging current. The DC fast charger's power electronics have to stay cool, too and it could well be that one of its power module is faulty or has bad cooling, but still works. I know that some chargers have multiple power modules and perhaps one has faulty cooling. Instead of taking the whole unit offline, perhaps it still functions with limited capability (and the network places a non urgent work order to replace the unit).

That would explain some of the curves I am getting with Electric Circuit. The curve matches an overtemperature throttling, but perhaps it wasn't the car.

 

[illidotane]

I have now confirmed the car is exhibiting the same behavior using Electrify Canada chargers this time, the last charging network in my area that I had not tried yet.

Out of the available chargers:
- Electric Circuit (AddÉnergie 125A or 200A CHAdeMO) (and chargers also operated by sister company FLO)
- Electric Circuit (ABB 175kW CHAdeMO)
- ChargePoint 125kW
- Electrify Canada (50kW) (today's session)
... all sessions exhibited the same behavior, therefore I am ruling the chargers out.

Today was with Electrify Canada and throttling started at 43% and was down at 30kW in no time and decreasing, showing the same exponential decay. Pack temperature was 17°C / 60°F when I stopped the session and left (51% SOC).

 

[GerryAZ]

A few comments:
1. The term "Gid" refers to an integer number available from the CAN Bus that comes directly from the LBC. Early technical information indicated that 1 "Gid" represents 80 Wh of energy. Leaf Spy uses this integer value to calculate the kWh number it displays. The name came from forum users, but the number behind it comes directly from the LBC. Leaf Spy has a setting for Wh/Gid that the user can configure so the kWh displayed will depend upon that setting. Early LEAF's would typically have a maximum of 281 or 282 at full charge when new. The highest number I recorded for my 2019 SL Plus was 737 (reached twice during the first three months), but it has more variation between charges than my earlier cars.
2. I have seen throttling from DCFC stations and from the car, depending upon conditions. EVgo stations here charge by the minute and the power companies in the Phoenix area have steep demand charges that kick in at 15 minutes. Coincidentally, the EVgo stations (which have their own service meter) often slow down at 15 minutes. Blink stations are flat rate (connection charge that will let you charge for up to an hour) and some slow down after 15 minutes while others go longer before tapering. I suspect the difference depends upon the host (store or other business location) power contract or differences in internal DCFC electronics.
3. DCFC will be slower when battery is cold and also when battery is hot. Battery temperatures do not need to be really cold to cause slow charging (40 F ambient is low enough to cause slower charging in my climate even with highway driving immediately before charging).

 

[SageBrush]

... all sessions exhibited the same behavior, therefore I am ruling the chargers out.

Today was with Electrify Canada and throttling started at 43% and was down at 30kW in no time and decreasing, showing the same exponential decay. Pack temperature was 17°C / 60°F when I stopped the session and left (51% SOC).

There are multiple variables in play. You have to control for pack temp and pack SoC to have any hope of making sense of it.

 

[illidotane]

There are multiple variables in play. You have to control for pack temp and pack SoC to have any hope of making sense of it.

That's what I'm trying to figure out. I've been trying to narrow it down and eliminating factors. In previous charges (in previous posts) I've tackled SoC and demonstrated the issue happens usually from 35% SoC onwards. Then, I tackled the pack temperature parameter by driving the car enough beforehand so that pack temperature would be above 5°C / 40°F. My last charge was at 17°C / 63°F and it was still throttling down under 26kW (43% SoC). Clearly no overtemperature here.

When those were adressed, I then thought about the chargers themselves, which was my previous post.

I've been testing different conditions one at a time in a methodical fashion i.e. when testing for another parameter, the previous parameter is kept "optimal". I believe I've truly been methodical so far in narrowing parameters, hence why I'm pulling my hair now.

 

[SageBrush]

I've been testing different conditions one at a time in a methodical fashion i.e. when testing for another parameter, the previous parameter is kept "optimal". I believe I've truly been methodical so far in narrowing parameters, hence why I'm pulling my hair now.

One variable, **all others** kept constant

 

[illidotane]

One variable, **all others** kept constant

This is what I tried to convey, yes.