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Discussion Starter #1 (Edited)
Hi friends,

I took my Zoe to London this weekend. Plugged into a few posts that were 7kW as found no free (well paid for via the Polar-Plus subscription) 22kWs (I realised I've been spoilt with Polar 22kW / free Sainsbury's Pod Point posts elsewhere!). London public charging is surprisingly awful (almost all 7kW or less) compared to the rest of the UK!
  • Plugged Zoe (R90) in on 52% and was getting charge estimates of FIVE hours. Had the posts knackered and flipped to 3kW? or does winter do weird things with charging (it's around 5oC in the UK right now)?
  • Also when away from London, I plugged into my usual favourite 22kW charger when it got to 99% I started preconditioning by pressing the remote button (while sat inside) and I noticed that the charge dropped out a few times over the 5 minutes (no errors, just acted like it was not plugged in and then continued charging, no notifications or alerts). Should I not pre-condition while charging (only while fully charged but plugged in?) I know the heater will refuse to work while charging without pretending you're pre-conditioning it (as discussed on Heating ZOE while charging). Maybe the pre-condition button is a hack and there's some technical reason we shouldn't mess with the heating while charging (as it inhibits battery cooling?)
  • I've noticed a few posts now start off with a ZE Services notification of "Slow" but then turn to "Accelerated" about half hour into the charge. Is this saying the Zoe is cold?
  • Also I have found a few Pod Point Open Charge where the LED is blue but then intermittently flashes Red on the post. I rang Pod Point and they said it shouldn't be doing that and said they'd send someone to fix the one I reported (but haven't yet).. but it does appear to be all the ones I've now seen. Has anyone ever seen a Pod Point that doesn't flash red intermittently? The 22kW post seemed to charge at 7kW for a while in this "Red" state.. but also possible car was just cold.
  • And finally (sorry this is a long one), say I could choose to weekly hammer the Zoe with a full 70mph before plugging into 22kW charge or a nice graceful 60mph would this help warm up the batteries at all? Is there anything I can do to keep the batteries warm to ensure a faster charge (warm the cabin beforehand to fire up the HVAC? Keep eco mode off and drive like I stole it and keep as close the speed limit as possible?)
I've also read some of the info on batteries and temperatures at Cooling the Zoe battery which hints that the BMS could be limiting charge speeds in cold weather (although it's talking specifically about very cold and 43kW charging) and there's also reference to weather affecting charge rates here and here.

Thanks :)
 

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Don't know much about the Zoe but the Pod Point chargers I've used for my i3 do flash red & I think blue or green once it's finished charging if that helps.. This is normal as far as I know :)
 

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Discussion Starter #3
Don't know much about the Zoe but the Pod Point chargers I've used for my i3 do flash red & I think blue or green once it's finished charging if that helps.. This is normal as far as I know :)
Thank you :). That saves me me wasting Pod Point's time reporting all these posts then :). They do it constantly whether something is plugged in or not and irrespective of the state of the charge. I hadn't noticed it before the evenings got darker and I was trying to work out why my charges were taking longer.
 

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Your welcome :) also it's the car that decides how fast to charge the battery, the post can supply as much charge as the car asks for up to its rated output.. That of corse presumes the post has no issues.. My i3 seems to vary whilst it's charging, sometimes the % goes up fairly quickly then it slows down but generally over an hour or 2 the total charge is the same.. My i3 doesn't show what power it's drawing just % it's going up by.. :)
 

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Co-author of CanZE. Q210 nov 2013
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Battery temp (which can easily differ 10C from ambient after a long drive) has a MASSIVE influence on max power intake the battery can take. For the ZE40 batteries the optimum lies roughly at 20C is the info I have. The 22 kW models like 25C all the way up to almost 40C for fast charging.

Also, the SOC is a big factor: for the Q90, don't expect 43kWh ever above 60% SOC.

In winter and when fast charging, my strong advise would therefor always be to charge immediately after a long drive, when it's still both cozy as well as as empty as possible from usage. Quit at 80%. Don't ever "top up" using rapids.
 

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42k miles on public charging. Am I an expert yet?
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Also I have found a few Pod Point Open Charge where the LED is blue but then intermittently flashes Red on the post. I rang Pod Point and they said it shouldn't be doing that and said they'd send someone to fix the one I reported (but haven't yet).. but it does appear to be all the ones I've now seen. Has anyone ever seen a Pod Point that doesn't flash red intermittently? The 22kW post seemed to charge at 7kW for a while in this "Red" state.. but also possible car was just cold.
Thank you :). That saves me me wasting Pod Point's time reporting all these posts then :). They do it constantly whether something is plugged in or not and irrespective of the state of the charge. I hadn't noticed it before the evenings got darker and I was trying to work out why my charges were taking longer.
Not quite... there's a wide range of Pod Point Open Charge status lights (it'd be a lot easier if they bothered to fit a screen to it!

You have:

Blue - Ready to charge
Solid Green - Charge Session in Progress, Charging
Flashing Green - Charge Session in Progress, Vehicle no longer taking power
Solid Red - Out of Service
Rapid Blink of Red when other colour showing - Communications Unavailable

When it's blinking red (it might be regular or irregular depending on the quality of the communications), the post isn't reporting status or receiving charge claim notifications. In my experience this tends to mean that the post will just carry on charging the car and not cut after 15 minutes, although I've never found a paid for Pod Point to know what happens if you're not on a free post.

Generally I see my charges in my account again after a while, so it tends to be temporary, but the post will still work so long as it's Blue when you start.
 

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Discussion Starter #7
Thanks both, everything I needed to know :)

I accidentally found a post on myrenaultzoe.com which talks about 2 hour long charging when it's cold (while I was looking up what the limits were on driving on flooded roads).. looks like I'll just have to ride this cold weather out.
 

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Thanks both, everything I needed to know :)

I accidentally found a post on myrenaultzoe.com which talks about 2 hour long charging when it's cold (while I was looking up what the limits were on driving on flooded roads).. looks like I'll just have to ride this cold weather out.
Pleasure - I'm pleased that posted actually as it said there was an error when I tried and it took ages to write!

Yeah....in general I find pretty much everything battery slows down a bit in the cold. I've seen a noticeable drop in speed in the DBT rapid chargers I use regularly, although the Polar Ultrachargers seem to be holding up OK.
 

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Co-author of CanZE. Q210 nov 2013
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@AndyK Not sure i you refer to Leaf or ZOE. For the 22 kW ZOE I have posted several times a sheet showing the power level the battery can take in relation to battery temperature (lowest module) and SOC. Excluding of course the max setting of the chargepoint, it doesn't regulate anything; it's really the car throttling.
 

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42k miles on public charging. Am I an expert yet?
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@AndyK Not sure i you refer to Leaf or ZOE. For the 22 kW ZOE I have posted several times a sheet showing the power level the battery can take in relation to battery temperature (lowest module) and SOC. Excluding of course the max setting of the chargepoint, it doesn't regulate anything; it's really the car throttling.
I'm driving a Leaf.

I'm not convinced it's the car - it still charges very quickly on the Ultrachargers, as I said, although I agree most of the time it's the car. I think it's just the DBT chargers that don't work as well in the very cold (they aren't known for their brilliance overall really!). That's my impression anyway - I'd do some tests, but I can't think of a possible way of making them fair :(
 

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I'm driving a Leaf.

I'm not convinced it's the car - it still charges very quickly on the Ultrachargers, as I said, although I agree most of the time it's the car. I think it's just the DBT chargers that don't work as well in the very cold (they aren't known for their brilliance overall really!). That's my impression anyway - I'd do some tests, but I can't think of a possible way of making them fair :(
I think it's very unlikely that the rapid chargers themselves will limit the charge rate when cold. Heat is the enemy of electronics, especially anything that dissipates a lot of power like a rapid charger. It will throttle (or shut off) if it gets too hot, but cold ambient conditions are actually a good thing for something like a charger, not a bad thing. (Not unless you get really cold - like -40C or more, then you can start to run into problems where some semiconductors don't work properly at very low temperatures, but -20C no problem at all)

On the other hand Lithium Ion battery charge rates most definitely must be throttled back when they are cold - otherwise plating of metallic lithium on the anode occurs, this causes irreversible damage to the battery in the form of dendrite growth which causes capacity loss and left unchecked this will eventually cause the cell to short circuit and catch fire...

So all EV battery management systems avoid this by have a "profile" programmed into them that lets them know what charge rates are acceptable at a given cell temperature. Below a certain temperature threshold (lets say 10 degrees) the charge rate will be progressively reduced with reducing temperature to stay within safe boundaries where dendrite growth will not occur, and below a second threshold (lets say -20C) you will reach a point where no charging is allowed at all.

Tesla's deal with this issue by using active heating to heat the battery before supercharging - apparently if you plug a cold Tesla into a supercharger in really cold (Canadian) winter conditions the supercharger is actually just running the battery heater to heat the battery up for quite a while before it even starts charging the battery itself. This allows a Tesla to Supercharge even in extremely cold ambient conditions.

A car like mine with no battery heater would be completely unable to charge below whatever that lower threshold temperature might be, the only option would be (if you still had range left) to blast the car along the road quickly to warm the battery up enough to get it to the point where it could charge at a moderate rate, once that happens the heating from rapid charging would become self sustaining and the charge rate will climb. (Although charging is restricted at low temperatures you can still discharge - so you can still generate battery heat by driving the car)

If you start rapid charging above the lower threshold but below the upper threshold the charge will start without problems but start quite slowly and ramp up gradually as the battery naturally warms up...
 

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Discussion Starter #12 (Edited)
I have posted several times a sheet showing the power level the battery can take in relation to battery temperature (lowest module) and SOC.
Sorry, could you link us to it again? I've searched your posts, is it this one? Typical charging times table I'm using a 41kWh battery but they should be loosely comparable.

Another thing I've learnt today about cold Zoe is wasn't sure it if it was my imagination but the acceleration felt a bit off..

So I Googled and found this too:
  1. Capacity: a very cold battery doesn’t fully charge. It can be compared to a fuel tank that contracts in the cold. The result is, of course, reduced range.
  2. Power: a cold battery cannot provide all the power required by the motor, reflected in weaker acceleration.
  3. Charge: an overly cold battery cannot be charged too fast, making for longer "quick" charging times. Cold, however, has no impact on standard charging, via a Wall-Box.
Renault ZOE confidential #3: cold weather tests

Looks like effectively what happens in the cold is a charger can become a 3kWh or 7kWh (the Renault wall-box at the time the post was written would have probably been a 16A; 3kWh). Which would explain what I was seeing over the weekend..

I saw :
  • a 22kWh charger and a moderately cold car act like a 7kWh charger.
  • and a 7kWh charger and a very cold car act like a 3kWh charger.
 

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@Matthew Yes, that one. The ZE40 battery does not have the same behavior though. As I don't own one it's much harder to compile data but in very broad terms, it won't do 43 kW anywhere above 60% SOC and lower when not in the optimum temperature spot (from memory around 20C).

What you say about charger is basically semantics. The chargepoint just tells the car what it is able to supply; the car takes what it can. In your analogy a very cold car on a 43 kW rapid still only takes 3 kW.

I personally never noticed reduced power. "Very cold" is pretty hard to achieve in moderate climate if the car is used every day: it's so much mass that it's almost impossible to have it as cold as ambient in the early morning; at least it averages out ambient and if you "step on it", it can go up substantially; I have seen it hotter than ambient by over 10C after long and stiff drives/charge sessions. This is by no means invalidating what you quoted; if the thing gets really cold, well, there you are.
 

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Another thing I've learnt today about cold Zoe is wasn't sure it if it was my imagination but the acceleration felt a bit off..
I definitely notice a reduction in acceleration with a cold battery in my Ion - I start to notice it when it is below about 6 degrees. So a cold start in the morning at 0-3 degrees I'd say I'm losing about 20% of my acceleration subjectively although it does increase somewhat after I've driven a while.

I've also noticed in cold conditions near freezing that the acceleration immediately following a rapid charge jumps back up to its summer performance level, for a while anyway, presumably due to the battery temperature increasing.

So yes, cold batteries will reduce maximum acceleration on most EV's unless the EV has active heating of the battery or the battery has had time to warm up through use or rapid charging.

I haven't been through a full winter with my Ion yet so it will be interesting to see how it manages at -6C compared to 6C....
 

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-6C?!! That's Arctic conditions to us Southerners - we sometimes get a sharp frost though...:D
According to graphs I record we hit -6 in the mornings several times last November. Not this November, yet! Lowest I've seen this winter is -1 so far but there is still plenty of time. :D
 

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According to graphs I record we hit -6 in the mornings several times last November. Not this November, yet! Lowest I've seen this winter is -1 so far but there is still plenty of time. :D

I've seen minus 3 a couple of times now (east Coast of Scotland). Another fellow Zoe owner has seen minus 4 a few miles further east/north of me.
 

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I've seen minus 3 a couple of times now (east Coast of Scotland). Another fellow Zoe owner has seen minus 4 a few miles further east/north of me.
I had to put my wooly socks on last night...the South Coast was almost in single figures! :D
 

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According to graphs I record we hit -6 in the mornings several times last November. Not this November, yet! Lowest I've seen this winter is -1 so far but there is still plenty of time. :D
I've seen -1 down in Sussex....only once, but we're only 9 days into November and haven't even got to winter yet ;)
 

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Discussion Starter #20
Apologies for the source but this is what the UK is going through at the moment : Britain to be colder than Iceland this weekend

@Matthew Yes, that one. The ZE40 battery does not have the same behavior though.
Your chart seems pretty accurate from my anecdotal experiences (of course if it's 1-5kWh out I'm not really going to know)

As I don't own one it's much harder to compile data
Short of buying you one (sorry) is there any way I can help gather the data for you?

at 0-3 degrees I'd say I'm losing about 20% of my acceleration
That's what it has been in the UK past week and set to continue.

I've seen posts saying in certain regions Zoe's battery heater is more powerful.. which implies regular Zoe at least has one (albeit not as strong), did we ever reach a verdict as to whether regular Zoe has any ability to use the HVAC as the heater (rather than just cooling)? I'm surprised Renault disable the heater during a charge session, surely if the battery is cold shoving the heater on might only help it?
 
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