2018 Leaf SL - DCFC seems slow (rarely above 40kW)

I am trying to determine whether or not to ask my dealer to pursue investigating my Leaf for slower than expected DCFC.

I have the appropriate software update installed (NTB19-056) and confirmed the firmware through LeafSpy (5SA3B). However the highest speed I have ever seen at a 50+ kW DCFC has been 42 kW and only for a minute before it dropped under 40. That was on a cold Canadian winter day with the battery at 55% SOC and temp of 28C (83F).

A few days ago I was using a brand new DCFC and got 38kW at under 50% SOC (this was my first charge of the day). Shortly after a 2013 Leaf tried it and was at 47kW.

And even though I have the rapidgate fix, if I do more than two DCFCs in a day the rate drops to around 20kW by the third station. I should note that I've only done that twice in 2 years, once in the winter and once in the summer (in the summer I got a battery heat warning after the third charge).

Does this sound normal at all? I've struggled to find much info on long range travel experiences post rapidgate fix. Thanks in advance for any info!

Have a Plugshare link to or the address of the DC FCs in question? A label might help, as often the amperage is the bottleneck.

Some DC FCs are rated via some crazy voltage (e.g. volts), so a "50 kW" charger might really be 50 kW at 500 volts (500 volts * 100 amps = 50,000 watts = 50 kW). On the flip side, I've used some EVgo 100 amp (e.g. BTC "Fatboy") chargers that seem to have been upgraded (but labels not changed) where my Bolt will get almost 50 kW despite the labels saying 100 amps.

cwerdna said:

Have a Plugshare link to or the address of the DC FCs in question? A label might help, as often the amperage is the bottleneck.

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This is not a DCFC limitation, it's been with numerous stations over the last couple of years. I see others on PlugShare reporting higher rates than I get for the station I am using. And as per my one example, another Leaf got 47kW at the same station where I maxed out at 38kW. I've used 100 kW capable stations (e.g. https://www.plugshare.com/location/73039) and been under 40 kW the whole time.

No problem with your car.

The majority of CHAdeMO chargers in the US are limited to either 100 or 125 Amps. The LEAF pack voltage at a SoC of ~ 50% is about 355 Volts so a 100 Amp charger would provide 0.355*100 = 35 kW and a 125 Amp charger would provide 0.355*125 = 44 kW

Should you ever have an opportunity to use a charger that is not the Amps bottleneck, the highest kW you will ever see is the amperage the car allows at that moment multiplied by the pack voltage. The amperage will never be higher than 200 Amps in the newer LEAF 40 and 62 kWh pack models but in the interests of pack health and safety the LEAF derates to lower Amps if the pack is too cool or too warm or the SoC is too low or too high.

These different factors that cap the Amps below the maximum are not specific to the LEAF, it is just Li battery chemistry. The LEAF problem is that due to absence of a TMS to regulate battery temperature the factors come into play sooner and are more obvious to the consumer.

If you are curious and would like to verify what I write above, buy an OBD2 adapter and put LeafSpy on your phone. You will be able to monitor Amps, pack temperature, and pack voltage during each charging session.

SageBrush said:

If you are curious and would like to verify what I write above, buy an OBD2 adapter and put LeafSpy on your phone. You will be able to monitor Amps and pack voltage during each charging session.

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Thanks for taking the time to reply. I am familiar with that and also have LeafSpy as mentioned in the original post, but again compared to a 24kW Leaf I seem to be consistently slower even at the same charger. I’m going to try and do a specific test this week at low SOC and cool battery, with another Leaf to compare against.

windsorsean said:

SageBrush said:

If you are curious and would like to verify what I write above, buy an OBD2 adapter and put LeafSpy on your phone. You will be able to monitor Amps and pack voltage during each charging session.

Click to expand...

Thanks for taking the time to reply. I am familiar with that and also have LeafSpy as mentioned in the original post, but again compared to a 24kW Leaf I seem to be consistently slower even at the same charger. I’m going to try and do a specific test this week at low SOC and cool battery, with another Leaf to compare against.

Click to expand...

If you can get both battery packs to test at similar temperatures you will have a basis for comparison. The practical problem you will run into is that the packs will heat up and change SoC at different rates so you can take a snapshot at the beginning of the charging session but after that you are comparing apples to oranges

Addendum:
I just remembered that I have a pile of LeafSpy voltage readings on my '24 kWh' pack over the years at different SoC at
https://goo.gl/photos/Evciakr2rA7AMQxTA
Pack voltage is 370 V at a SoC of ~ 40%, and it rises to 380 V at a SoC of 60%
Using those values,

At a 100 Amp charger (and no influence of temperature)
370 V = 37 kW
380 V = 38 kW

At a 125 Amp charger (and no influence of temperature)
370 V = 46 kW
380 V = 47.5 kW
Note that at a SoC of 60+% the LEAF battery may be curtailing the Max Amps

windsorsean said:

I've used 100 kW capable stations (e.g. https://www.plugshare.com/location/73039) and been under 40 kW the whole time.

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cwerdna is trying to tell you that the '100 kW capable' charging station does not apply to the LEAF. It might apply to a car with an 800 Volt system (because 800 V * 125 A = 100 kw.)

You have to wrap your head around a couple of things:
The charger will push a voltage ~ equal to the car pack voltage (but not more than the charger's rated maximum.)
Amperage will be the lesser of the charger's maximum or whatever the car allows moment by moment
Amps * Volts = Watts. A kW = 1000 watts

---
I get it. You bought the marketing crap that talked about 100 kW charging, and you still hold out hope that it is just a car fix away. Sorry, that is not going to happen. Ever. Physics says so. However, there are a handful of 200 Amp chargers around the country; and if EA ever fixes their CHAdeMO problems those too will be 200 Amps. Then you will see up to ~ 75 kW peak charging in ideal conditions. As for the notion that the 62 kWh pack should have charging rates *at least* as high as a 24 kWh LEAF (but hopefully much more,) you have to realize all LEAFs are 96S packs and the Gen1 LEAFs has 125 Amp electronics. Those cars are able to max out the typical CHAdeMO chargers around the country. Your new car's higher rated Amps is under utilized (for now, anyways.**) The small differences you see are due to temperature and SoC

** And perhaps forever, since Nissan has deprecated CHAdeMO in the USA.

Alright... I did a proper test this morning at a full 50kW capable station with LeafSpy logging enabled and here is what I found...

From 30% SOC the rate started at 45kW and went to a max of 47kW until 57% SOC at which point it started dropping quickly and was at 25kW by 75% SOC. I am not sure if this is due to battery temperature but based on this article I suspect it is.

I am surprised it slows down so quickly and at such a low SOC. I'll do a bit more testing at a higher initial SOC and low battery temp to see if it is purely temp related.

Here's a graph of what I found and here's a link to the source data.

Your LEAF data shows the Amps dropping from ~ 96F. I very much doubt that is temp related per se (or even at all) but I am not positive about a combined temp/SoC threshold. Mostly I think you just reached a SoC threshold. My rule of thumb is power will peak at ~ max_amps*375 volts. At this 125 Amp station that works out in kW to equal 46.8 kW. After ~ 375 pack voltage the Amps taper.

To summarize:
Your car is operating as designed
Both your 24 kWh and 40 kWh cars are 96S packs and they both max out the 125 Amps the chargers you have been using can supply
Since the battery chemistries are so similar, the Amp taper in relation to SoC will be very, very similar in the two models.

Lastly, do not be fooled by "50 kW charger" labels. They may not give your car the same peak power. E.g, one charger might be 100 Amp, 500 volt and the other might be 125 Amp, 400 Volt. Each would calculate out to 50 kW under ideal conditions but your LEAF will draw a maximum of ~ 100*380 watts at the first charger and 125*380 watts at the other one.

Kapisch ?

Good, now riddle time: Say I take my Tesla (which can take up to 250 kW at a V3 Supercharger) to the same EA station you went to and I use the CHAdeMO plug via an adapter. The adapter is not a bottleneck, and my pack is 96S. What ~ maximum power will I see ?

Extra extra credit: Say my car can use the CCS plug with an adapter that is not a bottleneck. The CCS charger is rated up to 350 kW (350 Amps, 1000 volts.) What peak power might I see under ideal conditions ? Is my car broken !?

SageBrush said:

Your car is operating as designed

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Thanks, that is what I was looking for. But I do have a friend with the same Leaf who will test and see if he gets the same SOC level drop off. And I'm going to do one more test starting at a higher SOC (like 50%) and cool battery just to make sure.

I am familiar with the way the power works and was never expecting higher rates than I am seeing, it was really about sustaining the rates. I am just trying to get to the bottom of whether it's a SOC limit (i.e. rate drops after 55%) or a temp limit (rate drops at 40C) or some combination of those. And of course if my Leaf is behaving as designed, which it probably is.

windsorsean said:

And I'm going to do one more test starting at a higher SOC (like 50%) and cool battery just to make sure.

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Don't wait too long, or you will be astonished at how low the Amps are when the pack is cold.

Such is the life of the TMS-less LEAF and the current CHAdeMO charging infrastructure:
Hot pack: rapid-gate !
Cold pack: cold-gate !
JUST RIGHT temperature pack: rare to find greater than 125 Amps CHAdeMO locations

Certai ly now that EA throttled their 200amp chademos down to 100 amps. ..there are some stations in Oklahoma advertising 200kW Chademos. Not sure when i will be through there, but would certainly like to give them a try.

SageBrush said:

Is my car broken !?

Click to expand...

Probably, it is a Tesla after all. :lol:

DougWantsALeaf said:

..there are some stations in Oklahoma advertising 200kW Chademos.

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Does not exist

303 W Ray Fine Blvd, Roland, OK 74954, United States

https://francis.energy/how-it-works#availability

Francis energy advertises on their site 200KW chademos.

Any Leag Plus owners on this board in Oklahoma?

Another test today, this time starting at a higher initial SOC and around the same initial battery temp. Sure enough the drop happened at exactly the same SOC as before (just under 57%), even though the temp was lower today when it hit that SOC. So this at least gives one definitive answer, that the 2018 Leaf will throttle down the charge rate at a specific SOC. I have a friend who is planning to do a similar test and see if he gets the reduction happening at the same SOC as me.

I know there is also a temperature based throttling that happens so maybe another time I'll see if I can figure out when that kicks in.

windsorsean said:

I know there is also a temperature based throttling that happens so maybe another time I'll see if I can figure out when that kicks in.

Click to expand...

Reported in this forum that the LEAF sets the peak Amps based on the pack temp at the *start* of charging ... at least up till the red bars. This is for rapid (hot battery) gate. Cold battery is a different story

DougWantsALeaf said:

303 W Ray Fine Blvd, Roland, OK 74954, United States
https://francis.energy/how-it-works#availability
Francis energy advertises on their site 200KW chademos.

Click to expand...

No,

They say 200 kW CCS+CHAdeMO.
In the same way that EA advertises '150 kW CCS+CHAdeMO.'

The highest advertised rate is reserved for CCS. CHAdeMO will probably be 125 Amps, but 100 Amp chargers certainly exist, as do a handful of 200 Amp chargers. Amps and kW are different measurement units. NO charger in existence that outputs 200 Amps will output 200 kW.
Of the dozen or so 200 Amp CHAdeMO in the US today, NONE will output 200 kW to a LEAF. If you are lucky you will see ~ 75 kW.

To summarize for you:
kW != Amp
kW != kWh

Notice how the words are different ?

Addendum: I called Francis technical support and asked what the maximum power is for their CHAdeMO. I was told it varies by location. Some are 50 kW and some are 70 kW. Meaning some are 125 Amps and some are 200 Amps.

Who wudda thunk ?!??

Drop will happen as soon as maximum cell voltage is reached.
Charging rate is 49.9kW for a second or two and then it starts throttling fast.
The newer the pack the later it happens.
The warmer the pack the later it happens.
My older 24kWh with lots of mileage drops at around 50-55%, depending on temperature.
The newer the pack the lower is internal resistance, therefore voltage is lower during charging
BEFORE reaching maximum voltage.

This is why my older pack starts charging at 44+kW at 15% SOC - as soon as DC charging starts
voltage spikes. And this results in somewhat faster juice flow.

Sagbrush, I also reached out to Francis, and they told me the charger in question runs at 200amps.

Still looking for that mythical 300amp Chademo.