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Hi

We have had our brand new Zoe ZE40 R90 for 6 months and have been very pleased with it, but about 3 weeks ago we had the dreaded "Stop - Electric Failure - Danger" notice in red. The car was charged to 100% two days prior and driven about 60miles the day before. On the morning of the failure the car was driven about a mile, then parked. On return the notice came up. The car still drove home OK, but there was no regenerative braking at all, although the brakes worked OK, they felt different. When home I tried to charge and it wouldn't start to charge at all.
I called Renault Assist who were very good and got the car picked up and delivered to the local Renault Dealer here on the Isle of Wight, they arranged for an automatic hire car from Enterprise, which we still have.

The dealer called back 3 days later saying, they suspected the Traction Battery as one cell in bank 6 was very low. They were at this stage waiting for a reply from Renault, who said they would have the Traction Battery collected and returned to them to investigate. So we are currently waiting for the battery to come back from France.

What concerns me the most is, if one cell failing stops the whole car in its tracks, how many others have had or will have Traction Battery problems. I was under the impression that the Pack had some sort of built in redundancy, to cope with this situation and the Battery Management System, could map out a failed cell, but I am now extremely worried about the long term battery health. So a steady decline in range will probably not occur, it will just one day stop working completely when one cell fails, no matter what the SOH says. Our range at the time of failure was 121 miles [80%] having done about 60ish since fully charging, so there was prior no indication of a problem. Incidentally the range on the App gradually dropped from 121 miles and 80% [Normal] to 68 miles and 77% by the time the battery was removed and we lost contact, which seems very odd.

Alan
 

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Co-author of CanZE. Q210 nov 2013
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Let's assume for the moment the diagnostic is right and it is indeed one bad cell (pair) that causes the problem. We have nothing else to go on.

First: the BMS cannot "disengage" one cell pair. All these batteries are constructed in a way that the current flows through each and every cell (like old fashioned Christmas tree lights). The BMS only measures each cell and can incur a tiny current for balancing and that is it. A design doing what you suggest would be wildly complex and full of power electronics, making the entire thing expensive and probably LESS reliable overall.

Second: Cells do fail, but not often. I own this car now for 5 years and follow two forums permanently. It has been reported, but it's really rare. Caveat: I can't prove that with numbers of course.

Third: Battery health, contrary to my own, and many others expectations, has more or less "proven" (same caveat, though many publish their SOH number here regularly) to be the least of their worries. Quite a few have had a mega-expensive PEC replacement (4K), I myself had the motor replaced (3K). All were payed by Renault BTW. What I am trying to say is this, without claiming to be "right": ride it out. It will be fixed. After that there is more than a fair chance that you will never look back and enjoy ZOE tremendously without ever having more than a burned out bulb.

Having said that: good luck. An event like this sucks big time.
 

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This could very well be the first documented case of a battery going full stop, let alone a 6 month old one. Battery lease or not you are covered by warranty :)

Please do keep us updated!

We are coming to the IOW soon - Will read this thread again on the ferry :)
 

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Hi

We have had our brand new Zoe ZE40 R90 for 6 months and have been very pleased with it, but about 3 weeks ago we had the dreaded "Stop - Electric Failure - Danger" notice in red. The car was charged to 100% two days prior and driven about 60miles the day before. On the morning of the failure the car was driven about a mile, then parked. On return the notice came up. The car still drove home OK, but there was no regenerative braking at all, although the brakes worked OK, they felt different. When home I tried to charge and it wouldn't start to charge at all.
I called Renault Assist who were very good and got the car picked up and delivered to the local Renault Dealer here on the Isle of Wight, they arranged for an automatic hire car from Enterprise, which we still have.

The dealer called back 3 days later saying, they suspected the Traction Battery as one cell in bank 6 was very low. They were at this stage waiting for a reply from Renault, who said they would have the Traction Battery collected and returned to them to investigate. So we are currently waiting for the battery to come back from France.

What concerns me the most is, if one cell failing stops the whole car in its tracks, how many others have had or will have Traction Battery problems. I was under the impression that the Pack had some sort of built in redundancy, to cope with this situation and the Battery Management System, could map out a failed cell, but I am now extremely worried about the long term battery health. So a steady decline in range will probably not occur, it will just one day stop working completely when one cell fails, no matter what the SOH says. Our range at the time of failure was 121 miles [80%] having done about 60ish since fully charging, so there was prior no indication of a problem. Incidentally the range on the App gradually dropped from 121 miles and 80% [Normal] to 68 miles and 77% by the time the battery was removed and we lost contact, which seems very odd.

Alan
Nope. One cell can bring a whole pack to a whining halt. They ALL have to work perfectly for the life of the car. Why do you think people are wary of EVs?
 

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No one is wary of ICE and a timing belt can ruin the engine..
 

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No one is wary of ICE and a timing belt can ruin the engine..
... because millions of cars have proved the technology robust. The failure rate, outside of maintenance problems, is vanishingly tiny.
 

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Well if you don't like EV's then why bother coming here? Go find a ICE forum...

Don't understand the mentality of some people
 

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I had my Traction Battery fixed last year ( Nov - Dec 2017 ) and i had only had it new from june 2017, since its been back all great so far ( touch wood ).

If i left the car for a hour or overnight the fault would disappear, but i needed the fault to show up so it could confirmed as a problem.

6th Dec 2017
New 12V Battery Charging Control Unit fitted 3 days later the fault is back.

I found the Fault at Last :
When l Pressed the Preheat button on the key fob while walking back to the car, And the car is still doing its preheat thing i then opened the Door & the Fault light appears.

Car will not charge & No Regen on slow down or braking

But Fault light never shows up while driving and only when parked up and then when you open any door the fault is there.

12v Battery was tested and result was 12.38

IMG_20171208_203824.jpg
 

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Discussion Starter #9
I found the Fault at Last :
When l Pressed the Preheat button on the key fob while walking back to the car, And the car is still doing its preheat thing i then opened the Door & the Fault light appears.

Car will not charge & No Regen on slow down or braking


View attachment 105768
When ours failed, the car bleeped when the door was opened, but no fault displayed until the door was shut. It drove home OK without any brake regen, I left it for an hour or so, but the fault was still there and would not charge so I rang Assist. Not seen it since Sept 18th, the hire Vauxhall Mokka is like a tractor in comparison to the Zoe, although it does actually drive!!
 

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This could very well be the third or forth documented case of a battery going full stop, let alone a 6 month old one. Battery lease or not you are covered by warranty :)
Had to correct myself - we all talked about never seeing a case and then like busses... lol
 

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Nope. One cell can bring a whole pack to a whining halt. They ALL have to work perfectly for the life of the car. Why do you think people are wary of EVs?
In an EV with an all series string of large format cells... which is admittedly most EV's at the moment.

But if you look at a design like Tesla's packs - they are incredibly redundant against individual cell failures due to their parallel series configuration. Each series block has about 12 cells in parallel each with individual fuse wires to the bus bar.

So if one cell goes open (or goes shorted, blowing it's individual fuse wire) you now have 11/12th of the original capacity for that series leg. Overall pack capacity will be reduced to 91% of what it originally was, but it's debatable if you would even notice that. And you could have a single cell failure in every series block without additional capacity loss. You would need two cells to fail in the same series block to cause further loss of capacity, and that is somewhat unlikely and still not catastrophic.

The single series string of large format cells in most EV's including my Ion makes me very nervous on the other hand...
 

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Co-author of CanZE. Q210 nov 2013
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ZOE has 96 pairs of 2 parallel cells in series. As they are relatively large cells that is somewhere between Tesla and iOn.
 

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In an EV with an all series string of large format cells... which is admittedly most EV's at the moment.

But if you look at a design like Tesla's packs - they are incredibly redundant against individual cell failures due to their parallel series configuration. Each series block has about 12 cells in parallel each with individual fuse wires to the bus bar.

So if one cell goes open (or goes shorted, blowing it's individual fuse wire) you now have 11/12th of the original capacity for that series leg. Overall pack capacity will be reduced to 91% of what it originally was, but it's debatable if you would even notice that. And you could have a single cell failure in every series block without additional capacity loss. You would need two cells to fail in the same series block to cause further loss of capacity, and that is somewhat unlikely and still not catastrophic.

The single series string of large format cells in most EV's including my Ion makes me very nervous on the other hand...
I agree/am aware that Tesla model is different, but having Teslas available for £100k doesn't help most people make a decision about an EV, so I avoided confusing the debate with that.

If your posit is that you accept my basic premise but would advocate a time ahead when such [Tesla-like] redundancies can be put into an EV pack, then I would not hesitate to agree with you.

The issue is that the large-format cell batteries are cost effective, so as always this is not an engineering-possibility issue, but meeting customers' target pricing with such products.

Would customers prefer the potential problems of a single cell going wrong and bricking the car, or paying as much as their house is worth for a car? ... The answer in a large number of customer cases is simple;- it is neither of those.
 

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ZOE has 96 pairs of 2 parallel cells in series. As they are relatively large cells that is somewhere between Tesla and iOn.
2 in parallel is simply too few to tolerate one failing. As @DBMandrake points out, looking at 12 cells in parallel there is some capacity there to tolerate a single cell failure.
 

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ZOE has 96 pairs of 2 parallel cells in series. As they are relatively large cells that is somewhere between Tesla and iOn.
Indeed, however I'd argue 2 parallel cells is not enough to ensure useful redundancy because a failure of one cell still halves your usable pack capacity and power output which is a huge and obvious change to the range, assuming the BMS would allow the car to be driven in such a state.

(Perhaps in a low power "limp mode" to get you to somewhere safe to pull over so that the remaining cell of the pair is not overloaded under peak power output that it would now be expected to deliver by itself)

This is very different to losing 1 cell out of 12 in a parallel group for an almost imperceptible 9% loss in range and power output.

I speculate that there are a lot of Tesla's driving around with one or more faulty cells that the owner is not even aware of. Statistically speaking failure of an individual cell is much higher when you have 6000-8000 cells instead of 80-160 cells, but the penalty for a cell failure is so small that it would go unnoticed without diagnostic equipment to interrogate the car.

The same applies to weak cells - a single weak cell with only 70% of the capacity of all the other cells in a series arragement would reduce the overall pack capacity to 70% as well. In the two in parallel case a single cell with a 70% capacity relative to the others would still reduce pack capacity to 85% whereas a single cell out of a group of 12 that was down to 70% the capacity of the others would only reduce pack capacity to 97.5% - an almost imperceptible change.

Large groups of small parallel cells are definitely the way to go if you want robustness and protection against individual cell failures.
 

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I agree/am aware that Tesla model is different, but having Teslas available for £100k doesn't help most people make a decision about an EV, so I avoided confusing the debate with that.
Until the fabled $35,000 Model 3 appears of course. (If it does ever come to exist. ;))

My reply was to address AlanIOW's concern about single cell failures to point out that it doesn't have to be this way, even if it currently is with most EV's. There is another way to deal with the problem, a way that Tesla have already chosen and appear to be sticking with. I don't see them going to large format cells any time soon.
The issue is that the large-format cell batteries are cost effective, so as always this is not an engineering-possibility issue, but meeting customers' target pricing with such products.

Would customers prefer the potential problems of a single cell going wrong and bricking the car, or paying as much as their house is worth for a car? ... The answer in a large number of customer cases is simple;- it is neither of those.
We keep hearing that large-format cells are more cost effective than many smaller cylindrical cells, but where is the on-the-ground mass production evidence for this ? Is there anyone producing large format cell packs for EV's of comparable size and capacity to Tesla who are undercutting their manufacturing cost per kWh at a pack level ? I don't think there is.

So at the moment I think this cost advantage of large format cells is theoretical only. Part of this may be that to match the number of cells and available space in a car and still achieve a target pack voltage large format cells need to be made to custom sizes for each model of car, whereas parallel groups of small cells can be made into any group sizes you like to fit available space and capacity requirements using identical mass produced cells - as Tesla do. There's no reason they couldn't use their 2170 cells in any pack in any vehicle they produce in future by just arranging them into different groupings. This gives great economies of scale for the actual cell manufacture.

Adequate cooling of large format cells also seems like a challenging problem since the surface area to volume ratio will be so much lower than a lot of smaller cells with a cooling loop weaving in-between the individual rows of cells. The large format cell may have a theoretical energy density advantage due to less wasted space between cells, but if that comes at the expense of difficulty cooling them I'm not sure that's a good trade off.
 

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Funny. Short version.
  • single cells in a string is a problem I think. It scares me
  • it is, the solution is a parallel series config, Tesla even does 12
  • Zoe uses that, but only with 2 (fact)
And here we go:
  • Two is not enough, presented as fact of course (for what? the usual suspects).
  • All EVs are shitty (either too expensive or too unreliable, the usual suspects).
  • Cooling big cells is a problem! (It isn't. The big cells aren't cylinders. ZOE's battery cooling system is actually real, well, cool and efective).
Meantime, in the real world, I am waiting for reliability figures from both architectures. Most of the above seems to be coming from, well, you know, a place with not that much light coming. Believing (I am using this word deliberately) that everything Tesla designs is the one and only all is severe Apple-itis. There are more roads leading to Rome.
 

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Funny. Short version.
Oh boy, here we go...
  • single cells in a string is a problem I think. It scares me
Yes it does scare me. Because I have two cells out of 88 in my Ion that appear to be going tits up in the last 6 months, which I have been keeping a close watch on. Slowly, granted, like the longest ever Hollywood death scene, but by this time next year I think I'll be looking at two cell replacements if I want to keep the car going, possibly sooner. So I think I have a good reason to be concerned about the reliability of individual cells in a series only configuration.
  • it is, the solution is a parallel series config, Tesla even does 12
  • Zoe uses that, but only with 2 (fact)
Correction, the solution is a parallel series configuration with many cells in parallel (~10 or so) so that the loss in performance from a cell failure is negligible.
And here we go:
  • Two is not enough, presented as fact of course (for what? the usual suspects).
Two cells in parallel does not solve the issue of gracefully dealing with individual cell failures with minimal impact on the performance of the pack, at all. This is a self evident fact proven by simple calculations, not an opinion. Disconnect one cell in your Zoe and continue to drive the car as normal. Good luck with that, and please remember to report the results back here... ;)
  • All EVs are shitty (either too expensive or too unreliable, the usual suspects).
Your words not mine. I just expressed valid concerns about the long term reliability and robustness of an all series configuration of cells. Something that I have good reason to be concerned about. I didn't even mention the Zoe at all, you brought that into the conversation.
  • Cooling big cells is a problem! (It isn't. The big cells aren't cylinders. ZOE's battery cooling system is actually real, well, cool and efective).
And how much heat does a Zoe with a 90/110kW motor generate in the battery pack ? Not much... Hell, even the Leaf with a 110kW motor can get by with NO cooling of the battery pack whatsoever. Not great to be fair, but it can manage. So at those power levels it doesn't take much for the cooling to be "adequate". A Zoe is hardly a high performance EV I'm afraid. About the only thing slower is an Ion!

Lets see how well those large format cells cope with cars putting out 300+ kW. Ever wonder why there have been delays in some of the high performance European EV's announced like those from Porsche ? Having problems with battery performance I wonder ? This was hinted at in an interview not so long ago.

One other thing to keep in mind with large format cells is that you can measure the outside temperature of the cell, but that doesn't necessarily give you a good indication of the peak temperature inside the cell. The larger a cell gets the more this inside to outside temperature differential can be.
Meantime, in the real world, I am waiting for reliability figures from both architectures. Most of the above seems to be coming from, well, you know, a place with not that much light coming.
Plenty of reliability and degradation data available on Tesla's, including 3rd party collection of data and certainly on the degradation front they are streets ahead of any car using large format cells. The data is out there if you want to go looking for it.
Believing (I am using this word deliberately) that everything Tesla designs is the one and only all is severe Apple-itis. There are more roads leading to Rome.
I think it's more of the opposite - people not willing to accept that in certain key areas Tesla made the right design decisions and others made the wrong decisions, due to it being cool to knock Tesla, and trying to attribute it to some sort of fanboyism instead of simply analysing the engineering impartially on its own merits.

The most obvious is in their battery pack designs which are a generation ahead of anyone else. They pioneered the skateboard battery and drive train layout(which everyone else is now moving to copy, funny that) and also the use of thousands of regular cylindrical cells in a massively redundant and robust parallel/series configuration with individually fused cells and an extremely effective cooling and heating system. They also have firewalls between different sections of the pack and ground facing flame/pressure release ports, when many other EV's (including my Ion) just shove a huge pile of flammable cells together inside a non fire proof plastic box and stick it under the floor. If one cell catches fire on my Ion it will quickly spread to all others without impediment and then to the car itself thanks to the decidedly non fireproof plastic top cover of the pack.

If you study the engineering of a stripped down Model S battery pack in fine detail it is a marvel of engineering that no other car manufacturer has duplicated yet. I have a number of criticisms of Tesla including design mistakes like the brain dead door handles in the Model S that all fail due to water ingress and wiring fatigue, but I'm afraid the battery pack is something they got absolutely right first time.

If their approach was so inferior to large format cells they would have switched for the Model 3, but they didn't. They doubled down on the cylindrical format with the slightly larger but still small 2170 cells.
 

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Discussion Starter #20
Update 2

Battery is back and fitted and we pick Zoe up Saturday morning a few days earlier than expected. The dealer has been great, even though they were not the supplying dealer, as yet they don't know what was done to the battery.

Given that there has been very few battery problems reported I'm wondering if I have just been unlucky or have I somehow caused the failure. The final charge before the failure was done with a genuine Renault Granny Cable, is there any reason a slow rate of charge could cause a cell failure. It seems counter-intuitive but why do Renault only say granny cables are only for Occasional Use? Is it because the granny cable is not up to constant use or the car's battery or charging circuits prefer a higher rate of charge?
 
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