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Discussion Starter #1
Hi all
My 2018 leaf is in the dealers in the morning for the earth strap recall and the rapid gate update.
My car although it says will charge at 50KW only ever at best has done 45KW for a short time before dropping as the % goes up.
Will this update cure that does anyone know?

On another point I set off to a charge station 7 miles away from me with 13 miles on the dash. I got to 0% 3.5 miles before the charger yet still made it!!! On my previous 24kw leaf 0% ment limp mode and recovery truck? Anyone else with similar experiences?
Thanks mike
 

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A Rapid charger will be 50kW at very best, at the charger itself. Between the charger unit and your battery there will be some loss. This is perfectly normal. Also remember that a number of chargers are limited. The likes of DBT units can't provide any more than 42kW.

You could try plugging into one of the HPCs which can do greater speeds than 50kW. You may see a little more from that. I know some cars will hit the exact limit with these chargers and give you the full 50, but others will not. It depends on the voltage of your battery, thermals, software etc. I definitely wouldn't be concerned about this charging speed though.

The update will fix the charge speed from dropping so much after a couple of rapid charge sessions mainly. On a first charge, with a warm but not hot battery, the best I've seen is 46kW I think, and then it would drop as the percentage rises. The 40kWh model seems to have a similar charging rate to the original 24kWh, where it starts to slow down fairly early. Why they didn't stick with their later 30kWh where you can rapid charge your way to the low 90's SOC before any significant slow downs, I do not know.

You're comparing two different cars. The 24kWh model had a smaller battery, was programmed to handle '0%' differently, and also its pretty well known that the original LEAFs were very inaccurate once you get below 20% charge. While your charge would go down in a very steady fashion to that point, after that you could end up either seeing 1% lasting you 5 miles, or 5 yards with the charge indicator dropping erratically.

The new models have a small buffer at zero more like ICE cars do. So you do always have a little more range than claimed, but I'm not sure how much I'd trust it.
 

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Discussion Starter #3
Thanks for the reply. Yes that would seem exactly as to what is happening but I am almost sure from 85% now seems slower to charge to 100%.
I am now sitting on a rapid charger and from 90% seems I'm wasting my time being here.
 

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Your "problems" seem fairly normal.

I have never seen more than 45 kW charging speed on my 40 kWh Leaf. YMMV with quality of charging points, I've seen as low as 30 kW on a "50 kW" point even at fairly low SOC and normal temperatures.

As far as charging above 90%, yes, PLEASE don't sit at a rapid charger over 80% if there's someone else waiting and over 90% in any case, as you see it can literally take hours to get to 100%. There is no difference between using 300 kW rapid charger or a granny charger for the last couple of percent. It will be painfully slow.
 

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I have a 40 KWh - 2 Zero - I did achieve a 46 Kw charge rate once, on Instavolt - but it was only for a very short time and then dropped back to the usual 43-44 Kws. The charge rate depends on many variables - out side temperature - battery temperature - SOC of the battery on commencing charging, What you described sound absolutely normal,

When the GOM runs down to the 2 dashes, there is about 10 miles left, if you take it gingerly (less with hills)

Since I had the rapid gate software fix, if I am 20% or above SOC on commencing charging, then I can always get to 92% SOC in 45 minutes allotted on EH chargers. (80% SOC in 35 Minutes)
 

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Thanks for the reply. Yes that would seem exactly as to what is happening but I am almost sure from 85% now seems slower to charge to 100%.
I am now sitting on a rapid charger and from 90% seems I'm wasting my time being here.
And anyone elses waiting for a charge as well. So dont, unless you absolutely need that last 10-15% to get to your destination.
 

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Why does everyone think that the purpose of a rapid charger is to fully charge their car? The idea of a rapid charge is to provide enough juice (typically 80ish%) so that you can move onto either your final destination or, if you are doing a road trip, to the next charge point. Exactly as @AnotherJoe stated in the post above.

With regard to the charging speeds this is down to three core issues - this has been discussed umpteen times and has been summarised by a number of members above as well.

  • Firstly, each rapid charger provides an optimum charge rate and you would very rarely get the 50 / 100kWh charge rate that the manufacturers claim their cars will handle (even the new IONIQ doesn't reach the charging speeds Hyundai claim - see various youtube videos). Also the older style rapid chargers are not as efficient as the newer charge points (the Ecotricity points are the old style - the ones found at Polar (or most other charge points) are much more efficient).
  • The charge rate will also vary on a number of external conditions (e.g. SOH of battery, ambient temperature and battery temperature (exactly as @GOSPORT DAVE advised above.
  • Laws of physics. The higher the SOH of a battery, the slower the charge rate. In addition to losing some efficiency between the charger and the car (via the connection cable), when the battery gets "fuller", the slower the charge - this occurs in both when rapid and charging via the conventional cables (granny or 3/6kW).
Also, do note that a Chadamo charger has a different efficiency to a CCS charge point.

With regards to the difference in LEAF models. The software on all three LEAF variants are not the same. The throttle rate of the 24kW LEAF was higher (i.e. you can reach a higher battery SOH before the charge rate falls). Likewise, with the 30kW, you could reach a fairly high charge on the battery before the charge rate tapers off. With the original 40kW LEAF, the charge rate did taper off around 65-75%, which Nissan advised was to self protect the battery, but since the software upgrade, this "protection" has been removed to a certain extent so you can now charge to a higher %age.

Finally, do remember that you do not have the full capacity of battery charge on any EV as there is always a certain %age that is not available for use. This probably explains why you were able to get to 0% and still have enough juice.

So to answer your questions: No, the rapid gate software update will not increase the rate of charge and yes, the SOC reached before you grind to a halt differs between the different models.

Hope this helps...
 

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Finally, do remember that you do not have the full capacity of battery charge on any EV as there is always a certain %age that is not available for use. This probably explains why you were able to get to 0% and still have enough juice.
The part of the battery that is not available for use is just that - you can't use it. It will be down to how the charge level is mapped to the percentages - in this case 0% still has some miles. Most likely they thought that since its a bigger battery they can afford to drop it to 0% sooner and give you some miles on 0% rather than it stopping when it hits 0, and that way they are encouraging people to charge sooner and not run out (saves them paying for so many trucks I guess!!).
 

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Why does everyone think that the purpose of a rapid charger is to fully charge their car?
But surely it is the intention of any charger. Doesn't the 80% come from a purely technical limitation? If not, the 80% is just a random figure plucked out the air.

I sometimes sit on rapids to get above 80% in situations where I know I'm driving into a desert for chargers.
 

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But surely it is the intention of any charger. Doesn't the 80% come from a purely technical limitation? If not, the 80% is just a random figure plucked out the air.

I sometimes sit on rapids to get above 80% in situations where I know I'm driving into a desert for chargers.
It is a lot slower to charge above 80%, some rapids actually stop at 80% and many have time limits (plus some have overstay fees).

By sitting on a rapid above 80% you are blocking the charger for a long time, so its generally accepted practice to charge to 80% and then roll on to the next charger and do the same - its faster for you and the charger is free for someone else. Of course as you say if there are no chargers within 80% range of your battery and you need 100% then you need it, and i've done it myself when there are no rapids on that route but I can get home on about 95%.

If I have to do so I either stay with the car or leave a note on the dash with my phone number if someone needs to charge. If there were slower chargers (e.g. some 7kw posts and some rapids, or a 7kw further along the route) then you might as well go to one of those as you'll most likely get the same charge rate on a rapid at 90% as you will on a 7kw post.

Cheers.
 

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If I have to do so I either stay with the car or leave a note on the dash with my phone number if someone needs to charge. If there were slower chargers (e.g. some 7kw posts and some rapids, or a 7kw further along the route) then you might as well go to one of those as you'll most likely get the same charge rate on a rapid at 90% as you will on a 7kw post.
This sort of etiquette is something to be encouraged! 👏
How can we get this out to a larger audience as more people move to EVs and PHEVs?
Around my way there is some free parking for up to 4 hours if charging at a 7kW post. This often results in (mainly PHEV) owners leaving their vehicle connected to the post long after they finish charging to get free parking, and there is no enforcement of the "whilst charging" caveat on the rule despite the posts changing colour when the charge is complete.
 

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Discussion Starter #12
Thank you all for the reply. I have had the update now and seen I can get 46kwh for a very short time as I always use the same charger so know it well.
I dont think most people charge to 100% on a rapid but I am sat here just now with my 2 kids asleep in the back and if they sleep for ages I'll charge to 100% if no one else needs the charger and here in scotland it's free to charge off a rapid so saves my electric bill. No doubt that will change soon.
I know this charger will do 46kwh and my battery is cool as I just drove here from my house but it started off fast and went up to 46kwh all the way from 20% but got to 40% and went down to 30kwh now at 65% @ 21kwh? Battery is still cool just seem to have a mind of it's own.
 

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Once the battery starts to fill up, the voltage in the pack rises. Eg suppose your EV had 100 cells in series, these may be at 3.6V each when "empty", and 4.1V when "full". So if the charger has a max of say 440V, then when battery is empty, it has 80V in hand to pump high current into your battery. The BMS will make sure the current is limited so as not to damage yr battery. But when nearly full, the charger has only say 30V in hand, and that may not be enough to keep charging at 46 kW, so charging rate goes down. The power going in = this voltage margin times the current, so reduces as both these values reduce. Figures here are v approx for illustration, am not sure precisely what actual V the Rapids operate at.
 

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Once the battery starts to fill up, the voltage in the pack rises.
For my 13 Reg Sunderland built 24 kWh Leaf, on the DBT chargers (the only ones which display the DC current and voltage), it appears the DBT charger pushes out 106A until the voltage reaches around 396V, when the voltage leaving the charger is held steady and the current drops. This will all be under the control of the BMS.

From the occasional observation of a voltage at 0A before charging actually starts, and that it is followed by a jump of about 10 V as the current rises to 106A, I have concluded that the pack (and possibly wiring) has an impedance of about 0.1 Ohms (more on a cold battery and less on a warm one) which means that the current will remain at 106A until the pack internal voltage reaches around 385V, then the current reduces as the pack internal voltage rises (ie. 50A with a pack internal voltage of 391V) and consequently the speed that the %SOC rises similarly slows.
 
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