Battery degradation: official test?

Renault Twizy
#1

I recently bought a second hand 2012 Twizy, with around 9.000 kms on the clock. It is quite the funkiest little car to drive.

But I have got the impression its range is less than the new Twizy I tested prior to buying my unit.
For the test, I drove the brand new test-unit from the dealer to my house and back. The Renault dealer is on the same road as my job, just 8 km further. It was a total of 60,5 km and I had 4 km left of expected range.
My commute is just 45 km on that same road so I was expecting to get back home with at least 10km of expected range left, if not more. That is not always the case.

Since I lease the battery from Overlease, I demanded a free test to check its status. I got an appointment at an official Renault Z.E. dealer nearby. They told me the test to check the degradation of the battery would take almost a full day. But after I left the car, they called me in 30 minutes to pick it up. They told me the test was done and it was at 100% capacity. I tried to explain to them that is hardly possible, since the car was from 2012. I found out they just plugged the car to a computer and the item regarding the battery only showed two values, total capacity=100% and current capacity=46% (meaning the battery was currently half charged).

I called Renault customer support and they were not certainly of any help. They seemed not to have a clue about how to perform such check to the battery. I called Overlease and explained the issue. I’m pretty sure the test performed to my car was not the proper one to determine the degradation of the battery.

They just took note and told me they would forward my question to tech support, and let me know whether I should take the Twizy back to the dealer or take it somewhere else for the test I want to perform.

It just seems to me weird not even Overlease is sure about the degradation test. Hasn’t anybody done it yet in Spain? What is the test like? Do they upgrade the firmware or anything like that i should be concerned about during this procedure?

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#2

There are so many variables like external temp and sticky brakes, never mind driving style. SO range is hard to judge.

I too would like to know how to check the traction battery. Some one suggested that you fully chrage it until the fan cut out. Then plug it back in and see the reading on the dash. After 15,000 miles (5 years) it reads 98% charged. However my range feels less. I do the same journey everyday and so have a good idea of variance. but even in all this heat the range is lower than I expected.

#3

Surely those two variables are just max / current value, but not related to the actual charge available. I would think for that they would have to hook the battery directly up to something, expel all charge and then charge again to do some measurements

#4

After 5 years and 10500 miles the battery still seems pretty good. Ok it is the summer and we had a heatwave last week so I was getting a charge of 42 miles which went up a bit to 47 on my commute to work. However, last winter I was lucky to get 33 miles after a full charge. It showed 100% but the range dropped dramatically in the cold and I was charging it every other day (after driving about 20 miles). I asked Renault then about when they would replace batteries. They said when they fall below a 75% charge. Is this winter or summer charging? You can bet they will test the battery in a nice warm inside garage!

I asked if they would consider reducing the rental to reflect the loss of charge. You can imagine the response. We all know that Renault finance are not nice people to deal with!

#5

Almost 2 weeks and still haven’t received a proper answer from Overlease. It just seem really weird to me that they include the 75% dagradation limit on the contract, but they aren’t willing to give any information about how to carry the test that would determine the obligation for them to replace the battery.

The fact that it seems no users around the forum have done such battery test might indicate the high quality of the battery, or the reluctancy of Overlease to carry out such test…

#6

On Leafs the battery bars disappear so they don’t appear filled. I had assumed that the Twizy would show 9 bars out of 10 then it lost between 10% and 20%. ie. 2 bars missing 20% - 30% loss and time to ask Renault for a battery fix.

The guarantee only returns the battery to be over 75% capacity not back to 100%. Which is a little unfair when there is no reduction in lease.

#7

I would have thought for the Twizy to be similar to a laptop: always showing the 10 bars, only draining faster as the properties of the battery degrade.

#8

Agreed I was just showing what the Leaf and presumably the Zoe do.

#9

True, in that case it is much easier for the owner to determine the state of the battery pack…unlike the Twizy.

#10

Just to keep you updated, I have written a couple of times to Overlease about the battery diagnostics. It is really frustrating, but I’m not giving up just yet. They argue the test Renault did on my vehicle is enough to determine the battery status. I told them I highly doubt a 20 min check on all of the car systems is the right test.
I’m bringing into the debate the fact that they are not honouring the contract, preventing me to know if they have to replace the battery, in case it’s capacity has been reduced to 75%
They have assured me they’ll contact Renault tech support to find out about the type of diagnostic that should be carried out.

#11

Overlease has finally shut the door to further dealing with this subject. The reply was:

Renault Technical services agree the procedure carried out by the Renault dealer workshop is the right one to evaluate the current state of the battery. The tested battery charging capacity is within the correct limits.

I then asked them to provide to me the exact charging capacity figure.

They had the guts to reply they cannot provide that information to the owner of the vehicle. They only confirm that I took the car to an official dealer and that the battery is within the correct limits.

I’m totally disappointed with this load of crap. But I guess it is the end of this discussion for now. Let contract renewal come in 10 months…

#12

Thanks very much for this thread. As the owner of a 2012 model Twizy I have an interest in knowing that this test will be done properly when the time comes, as, I guess, do we all.

I would certainly be interested, if others were too, in taking this further, perhaps by finding someone who could do an independent test of the battery capacity. Certainly, I can take mine to a low state of charge and then use an in-line energy monitor to gauge the energy drawn from the mains during charging. In order to know the capacity of the battery, then, one would have to know or estimate the efficiency of the charger, but that might not be too difficult within bounds. Certainly one could chart over time the energy needed to charge, and note if it dropped markedly.

Finally, I wonder if it might be worth getting the UK Consumer Association (Which?). I am a member, of that helps.

I certainly don’t think that things should be left as they are - totally unsatisfactory.

Best wishes, Mike.

#13

Outside of battery damage and a breakdown the dealerships are not being honest when dealing with warranty based items, the battery included. I was at the dealership yesterday getting the charge plug port replaced since the cover flap broke off on the Zoe, and it was under warranty where the plug costs apparently £600. My prior visits had the R-link update and the BMS update. I managed to check that the R-link was the current and updated version. It took a while to research if I had the latest BMS version (old version symptom: 99% charge ticks on at 90% of actual charge, leaving you with over 2.xKWh to charge to get to 100% on the 22KWh battery). This issue is resolved in the latest BMS. Sure enough I took the time to test it on an Electrocity charge point that gives you the KW’s as you charge. I confronted the service desk with my request to prove the BMS was updated. They do not share any paperwork on warranty items. They did say it was done. I then brought my facts to the table… they brought in the mechanic, and then they admitted that the BMS was not current. Both knew I was not going to let that go, and immediately scheduled an apt and offered a free rental vehicle since it takes 1.5 days to do this. The reason it takes so long is that there is a battery calibration to be done with a BMS update. The battery must charge up to 100% overnight. The free ride was an appeasement tactic given I called them out on a lie. Of course at that point I will be asking to give me the battery degradation percentage, but I need to research the technical procedure on how that is measured to ensure they don’t BS me again. Having the latest BMS is crucial for both warranty and management of the battery, yet, the dealerships don’t seem to care much for EV’s as a category… like the customer ChargeMaster on location that has been out of service for about 6-months (the dealership owns it, and upon my several escalations to the GM is finally getting fixed). My advice, get your BMS updated first, since that will have to calibrate the battery, and it should also give you the capacity charged. My version of verification is going to be Electrocity charge point on an empty battery to see how many KW’s it takes to charge. Hope that helps :wink:

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#14

The key point here is this is NOT a Twizy. DO NOT get the BMS updated on a Twizy if you run or want to run the Power Box.

Interesting problem though trying to get the dealer to actually do what they say they have done. Is there no were in the menu’s that show you the software version? Unless yo know what the update fixes (like you did) there is no way of knowing if it has been done. At least Tesla show the version numbers.

If the updates don’t change anything you are likely to use or can reasonably easily check then you will never know (or need to know).

How do we get the battery SOH checked on a Twizy?

#15

@osbrook definitely NOT on a Twizy. And to be honest, after my new battery from Renault, with all updated SW from my battery melting incident, the PowerBox logically came after and I am not changing a thing - the situation is as ideal as it gets (2012 Twizy, new battery in 2015 and PowerBox = FUN). Having both now I get to look at both sides of the situation… However it goes to show the traps the dealerships set up for you.

There is nothing in the vehicle that I know of that can give you the BMS version.

I am looking for the procedure used to measure the capacity of a Renault battery. The only method is what I stated with Electrocity - calibration could be questioned however. And you can’t put a fast charge on a Twizy in that scenario that I know of. For the Zoe, you have the BMS showing % charge vs the incoming measured KW being uploaded into the car’s battery - that seems a good way to get an indication of capacity. Range which varies on driving style and temperature is not a good method of determining capacity either, even though it would be an indicator as it would naturally be lower. Thus seeking a scientific method is key for a claim.

Additionally, unlike a Twizy where you only have bars of remaining charge, the Zoe has % battery left. It has been shown that the car still can drive and has power at 0%. This means that “true” calibration of charge to capacity is not a real measure of what you really have in the battery.

On the contractual side. The 75% of usable capacity guarantee from Renault maybe hard to claim given it is their tools and methods that would determine it. This is obviously a conflict of interest, unless there is full transparency with an independent audit of the methodology/code. For now, collecting the procedures and understanding the BMS capabilities and logic is needed to determine how to have a true measure of your battery’s status, and how it will stack up to a claim at 75%.

I don’t see an easy answer here unless Renault spills the beans on how it is done. Just getting a BMS update is a push in some cases (seen videos in Spain that show frustrated owners not getting their BMS updates due to lack of tech knowledge and incompetent dealerships). The warranty holds up for full failure, but can you measure capacity is the real problem… @kennethnilsen69 - do you know or have any insights on this for the Twizy?? Given you know much about the programming of its ECU :slight_smile:

#16

From Powerbox firmware version 1.78, you can check the capacity of your battery inside the Battery info menu. On the last page it has a value called A-Energy (Available Enargy) A Twizy Battery should be able to save 6.1kWh to be at 100% capasity (correction. It means 100% Available Energy capasity). 100% capacity is more than 6.1 but Renault promises 6.1 and that’s what BMS is configured to give you permission to use. 100% energy can be as high as 7kWh but this means nothing regarding the 75% guarantee. When A-Energy shows only 4.57kWh, you’re down to 75% of promisest capacity. Only then can you request a new battery.

The A-Energy value is 100% accurate and this is what your BMS measures via the shunt that is in the battery box (a shunt is an accurate current meter that all lithium BMS has)

To do a test yourself do the following.
Drive your battery completely empty (until the car stops)
Charge the car to 100% SOC and read from A-Energy (it should display 6.1 kWh to be “100%”)
now run the battery empty while on the Battery Info page and make sure everyone uses all 6.1kWh (charge it now again)

Now you should have a good overview of the battery’s real capacitance :slight_smile:

My English is not so good so hope someone understands what I mean :slight_smile:

#17

It will be wrong to just check the SOH. A worn/degraded battery can hold up to 100% SOH.
I will try to explain.
In a way you can compare a little with the health of a human being.
One can have a 60 year old who has 100% health and a 20 year old who also has 100% health.
But the capacity of them is not the same. A 20 year old has much more capacity than a 60 year old.(in most cases
)

Batteries are a bit of the same. SOH is calculated on the basis of several criteria such as the unevenness the battery cells are discharged on. For example, a battery that has 20 cells and if all of them are emitted equally from full to empty, they get a high and good SOH. If any cells are getting faster emty then others, you gets a bad SOH. In other words, this does not need to have anything about the capacity of the battery as long as all cells are wearing the same amount, the BMS will report high SOH. A battery that only has 50% capacity can still have 100% SOH

A low SOH indicates that something is wrong with the battery and should receive a service from qualified professionals. but not because of the capacity, although this obviously affects the capacity

it’s not so bad to get your BMS updated. Your Powerbox will not be affected by this and it will work just as well afterwards. It is the Firmware in your Sevcon Motor controller that must not be updated. But if updating your BMS will help something on a bad battery I strongly doubt. (but it can not hurt) But they can fool you. Keep in mind that they can configure a BMS to show what they want so it just seems that the battery has improved. Check A-Energy before and after a BMS update :slight_smile:

and again sorry for bad english. It is difficult to translate this in a sensible manner

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#18

@kennethnilsen69 you are awesome! I knew you were the man to ask to get to the bottom of it on the Twizy. And never worry about your English, it is more than adequate in giving us the insights we ask about. I am going to have to check out my PowerBox, and see where my version is at. I have not updated it since I got it from you, it maybe time to do the upgrade and check out the SOH of the Twizy. The real challenge is how do you get to tell Renault that your battery is below 75% without revealing that the PowerBox told you :grin: haha… but I do feel like that old man having a 20year old SOH at times, it must be the energy drinks :tropical_drink: :grinning: Thank you so much for the explanation!

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#19

Urgent!! :fearful:

Finally I found a 2015 traction battery!!! :cupid: I need help to find out how to test if the battery it’s good! :confused:
ps. I don’t have a Twizy yet so…(LOL! buying the battery before the car…this is quite impressive!) :joy: …I can afford it…but not a Twizy without battery… :cry:

He’ll probably accept a 1000euro deal…but I’ve no way clue how to check if the cells are dead or still alive and rechargable. I’ve asked him if the battery is complete with the BMS (even though I don’t even know if it’s inside the battery pack…anyway… :disappointed_relieved: he said it’s complete of all it’s parts…I guess he just unplugged it)

Any help is really welcomed! :heart_eyes:

#20

I have just had my battery tested and they tell me it’s perfect, charging 100%. I may be a bit dim but surely if I was getting a 45 miles range readout when fully charged in 2013 but now only 33 miles range fully charged in 2018 - surely the batteries are not delivering enough power? I run my car down to about 5 or 6 miles range before plugging in again and leave it until it has charged 100% and the fan stops. Rarely I need to plug in at about 18/20 miles if I am doing a long commute the next day but it sill only gives a maximum range of 33 miles. If the weather is warmer, I can sometimes get 37 miles!! Wow!!

The bottom line is, no matter whether the battery says it is 100% charged, it is the amount of miles that count. I used to charge once a week, now I charge up 3 times a week. Doesn’t this mean my batteries are not performing as well as they used to?

I am about to sign up for another 5 year battery lease and wonder whether they will ever replace them if they do not accept Twizy’s over 5 years old are not giving the promised range of 50 miles.