Battery degradation

[alohart]

Parking lots in apartment houses usually have a outlet pole shared by two spaces, with one outlet for one car. In most cases they have a built-in 2 hour timer. It also has a shared 16A fuse for two cars, so I'll have to make sure I won't charge while the neighbors car is being warmed.

For what it's worth, I performed the simple, reversible modification to bypass the timer in my Swedish carport's electrical outlet so that it provides power for as long as its power switch is on. I need to be able to balance-charge the battery pack in my Honda Insight hybrid which can take 15 hours at 0.35 amps. At such a low current, I obviously don't have to worry about burning out the fuse, and I'm not using so much power that my apartment association might complain

Engine block heaters can consume as much as 7 amps, so to avoid potential fuse problems, you would need to limit your charging to 8 amps or maybe a bit less to be safe. A Swedish company offers this very compact EVSE with charging currents that are adjustable to as low as 6 amps. This low charging rate would help keep your battery pack warm while it over many hours.

I hope that your housing association is more reasonable than many U.S. associations that make it difficult for apartment owners to charge their EV's. It took me more than a year to get approvals from my U.S. housing association, the local building department, etc., so that I could charge my i-MiEV in my apartment parking space.

 

[jsantala]

In my experience the engine block heaters are only 300-500W. It's the cabin heaters that can use 1000-2000W.

Anyway, that UM-EVSE v2 is really nice and I've looked at it before. It would do the job splendidly. It is a tad expensive though, so I'll have to sit on a bit.

One of these Mennekes adapters I may have to purchase rather soon, just to make sure I can use a Mennekes plug to charge at L2 speeds, if there's nothing else available:

https://evconnectors.com/Type-1-Electric-Vehicle-Charging-Cables-and-Sockets/Type-1-Connectors-16-amp/j1772-to-62196-2-16-amp-plugs-and-cable-dsi-dsiec-ev16p

They also have an adjustable J1772 cable, but it's with the stupid block and isn't any cheaper than the Swedish version:

https://evconnectors.com/Type-1-Electric-Vehicle-Charging-Cables-and-Sockets/Portable-16a-J1772-EVSE-Schuko-Euro-Domestic-Plug

 

[DaveMiller]

Isn't CC constant current, not contact current?
Dave

Correct Dave, but I think that jsantala is doing very well posting in a foreign language! ...

I agree. In no way did I intend anything offensive. My question was asking if there was a new term used today that I was unfamiliar with since I took an AC/DC fundamentals course way back in 1970.

I love this forum and my I-Miev, and don't want to discourage anyone from sharing good information. Jsantala wrote a very good post.

Dave

 

[JoeS]

... In no way did I intend anything offensive...

No worries at all, Dave, as we've all had our posts misconstrued and have misconstrued others' posts. I love the civility of this forum, and the astuteness of i-MiEV owners!

 

[martinwinlow]

Hi All,

Firstly to the OP, you can buy 2011, ex-lease Peugeot iOn's from dealers in the UK currently for around £7k. They typically have less than 5k miles (some have been as low as 1k) and are in very good condition. The iOn and C-Zero are identical except for the badges. You may care to quote this at your seller if it is not too late. Of course these cars are all right hand drive.

Secondly, for those who have had noticeable range reduction I am interested to learn if it has been reflected in any loss of 'fuel gauge' bars - like the aging LEAFs are showing. If all the initial loss is happening below turtle mode capacity level then I guess it will not show up in the bars. Obviously, it would be very useful for the buyer of a used i-MiEV to know that if all the bars are showing that the pack capacity is still pretty good... ie about 90% at least. Anyone got any thoughts/knowledge/experience on this?

Regards, Martin.

 

[Zelenec]

Secondly, for those who have had noticeable range reduction I am interested to learn if it has been reflected in any loss of 'fuel gauge' bars - like the aging LEAFs are showing. If all the initial loss is happening below turtle mode capacity level then I guess it will not show up in the bars. Obviously, it would be very useful for the buyer of a used i-MiEV to know that if all the bars are showing that the pack capacity is still pretty good... ie about 90% at least. Anyone got any thoughts/knowledge/experience on this?

Regards, Martin.

Loss of capacity (2Y, 50k km, -8%) in my case so far does not show in the disappearance of bars, but each bar lasts less kilometers. For example, when new, C-Zero was able to reach 16 km before first bar disappeared, now it's just impossible on flat terrain.

 

[Zelenec]

So the question is, what kind of battery degradation have you observed in your own iMiEVs over the years and miles driven? I'm only interested in actual user reports, not hearsay or guesswork. How far can you go with your pack now compared to new?

After two years and 50.000 kms I lost 8% of battery capacity and my car's range is also about 8-10% shorter. When it was new, it managed even 170 kms (careful lightfoot driving), now only 150-160 kms. I guess the car could be useful for my needs at least 10 years, if the rate of yearly degradation remains the same.

 

[martinwinlow]

After two years and 50.000 kms I lost 8% of battery capacity and my car's range is also about 8-10% shorter. When it was new, it managed even 170 kms (careful lightfoot driving), now only 150-160 kms. I guess the car could be useful for my needs at least 10 years, if the rate of yearly degradation remains the same.

And are you missing any 'fuel gauge' bars yet? MW

 

[Don]

And are you missing any 'fuel gauge' bars yet? MW

He said no

Loss of capacity (2Y, 50k km, -8%) in my case so far does not show in the disappearance of bars, but each bar lasts less kilometers. For example, when new, C-Zero was able to reach 16 km before first bar disappeared, now it's just impossible on flat terrain.

I don't believe any of us will ever see the loss of any 'fuel gauge bars' no matter how degraded our battery pack becomes - A 'full' battery of whatever capacity will always show 16 bars, but with the degradation, each bar will just represent less capacity

Don

 

[PV1]

I don't believe any of us will ever see the loss of any 'fuel gauge bars' no matter how degraded our battery pack becomes - A 'full' battery of whatever capacity will always show 16 bars, but with the degradation, each bar will just represent less capacity

I agree. Even with degraded packs, they still reach 100% SoC, so we'd see all 16 bars since the bars represent SoC. Now, if a pack is severely out of balance or on the verge of failing, then you would see charging stop before reaching 16 bars, since the battery couldn't reach 100% SoC. Something caused it stop early (HVC on a cell or two, for example). We've seen this behavior on the few cars with failed/defective packs.

 

[Barbagris]

From our russian friends:

ENERGY LEVEL GAUGE INDICATION:

The energy level of main battery is comprehensively determined based on the main battery consumption, battery cell voltage, battery cell temperature, driving history, and others. The calculation result is indicated on the combination meter.

CALCULATION FOR ENERGY LEVEL

The BMU comprehensively judges and calculates the battery level (%) from the main battery conditions including the electric consumption of the main battery, the battery cell voltage or the module temperature, and also from the travel history. The calculated battery level is sent to the EV-ECU through the CAN.

The key is "...including capacity adjustement", so yes, the car recalculates it and show 16 bars when is full.

 

[jsantala]

I just did a longer trip which would indicate my battery is in pretty good condition. It's a 2011 C-Zero with 11000km driven now.

I started with 96.5% SOC (all data according to CaniOn). Drove 81km using 10.242 Wh and ended up with 31.5% SOC.

96.5% - 31.5% = 65% so 10.242 Wh / 65% * 100% = 15.757 Wh total capacity from 100% to 0% SOC. Probably within margin of error.

 

[Barbagris]

The Austrian Automobil Club did a long-term test to the i-MiEV battery.

In 2011, the range of the i-MiEV was first measured by the dynamometer at the TUV Vienna, and three years and 40,000 km (25,000 miles) later, the same test was repeated. The result: The usable battery is decreased by 17%.

Source (german):

http://www.focus.de/auto/elektroauto/elektroauto-mit-17-prozent-kapazitaets-verlust-zeitbombe-akku-verlieren-elektroautos-schon-nach-drei-jahren-an-reichweite_id_4305025.html

 

[jsantala]

In 2011, the range of the i-MiEV was first measured by the dynamometer at the TUV Vienna, and three years and 40,000 km (25,000 miles) later, the same test was repeated. The result: The usable battery is decreased by 17%.

Not a very good result at all. However, no information on how the vehicle was used up to that point was given. It would be the most interesting information. Also, was there a single low capacity cell that was limiting the range or were the cells degraded evenly? Brings up more questions than answers.

 

[JoeS]

In 2011, the range of the i-MiEV was first measured by the dynamometer at the TUV Vienna, and three years and 40,000 km (25,000 miles) later, the same test was repeated. The result: The usable battery is decreased by 17%.

Not a very good result at all. However, no information on how the vehicle was used up to that point was given. It would be the most interesting information. Also, was there a single low capacity cell that was limiting the range or were the cells degraded evenly? Brings up more questions than answers.

Agree with jsantala, as battery degradation is certainly dependent on the care with which the battery pack was treated.

So, if we are considering purchasing a used i-MiEV and have convinced the seller to let us plug in CaniOn, one way of partially ascertaining the battery pack's health is to simply check to see if all the individual cells are very close and that there are no outliers. Now, the on-topic burning question remains: is there a quick way of ascertaining that used car's pack's capacity at a glance?

Is there any point for a potential buyer to insist that Mitsubishi perform a capacity test (perhaps offering to pay for that test)? Hmmm, this may be worth a phone call to the local Mitsu service department to see what they can offer.

 

[DonDakin]

I believe the most manufacturers are warranting the battery for capacity loss up to 70 %. So i guess we can expect something a little higher then that after 8 years. They must know something about capacity loss.

For the comment about if capacity loss was with one cell or multiple cells. I thinks its a moot point. Our battery is made up of 88 cells, capacity loss will no doubt come from the worst cell in the pack. Its the nature of the beast. Even if all cells in the pack deteriorate at exactly the same rate the result is the same while you are in warranty the pack would be replaced.

We still have 5.5 years remaining on battery warranty for 2012 used imievs. So excessive battery capacity loss should not be a concern for awhile.

A suppose in 2020 when you buy a used imiev with 200,000 km on it. You will want to have some idea of how many cells you will need to replace. Maybe then it will be nice to do a full charge and then turn the heater on full and watch the voltages drop looking for weak cells.

As that time you might just want to replace the entire pack with a higher capacity cell if available. But who knows even at 50 % loss the car is still good for 60 kms of range which for a lot of my driving would be fine.

As for me

I just did a full charge on my 2012. At 14 deg C my pack show 113 km range on a full charge.

Next summer I will try to see how much turtle i have left. So far i have not noticed any capacity loss. Perhaps its all coming out of the turtle. We will have to bring it to zero SOC to see.


Don.......

 

[jsantala]

It doesn't make much difference to the owner of the bad pack if there's one or twenty bad cells, but in general it would be of use to know whether in this case it's just a single bad cells killing the performance or are we to expect all cells to fall this fast. There is bound to be bad cells and having one bad show up in a test can ruin the reputation for thousands of good cells. That's why it would be interesting to know the reason behind the diminished capacity. If it's just a single bad cell they were out of luck - if it's all cells then we're all out of luck. Big difference.

 

[Kuuuurija]

There have been only few updates in Estonian media about status of more than 500 iMievs, that were bought from Mitsubishi in 2011 by Estonian Government.
Recent news told, that these cars are deteriorating much faster than expected. Now these cars can have only 60...70 kilometres maximum range per charging.
Viljandi Hospital owns 8 iMievs, 2 of them have already replaced battery.

Source (google translation): https://translate.google.ee/transla.../elektriautode-jaks-hakkab-raugema&edit-text=
Source (original): http://www.sakala.ajaleht.ee/3080789/elektriautode-jaks-hakkab-raugema

 

[jray3]

Thank you Kuuuurija
The photo of a snowbound i-MiEV on CHAdeMO makes me wonder is this capacity loss is due to the lithium plating issue in cold conditions. Any further data would be appreciated. I've always thought that one of Mitsubishi's very few technical errors was to not use the battery heating system for capacity and service life optimization, only for pack protection in extreme cold.

Hmmmmm....

 

[PV1]

The photo of a snowbound i-MiEV on CHAdeMO makes me wonder is this capacity loss is due to the lithium plating issue in cold conditions.

My thoughts exactly. Except for a couple of failures, I haven't heard of any major capacity loss from cars in warmer climates.

A more aggressive thermal management system would be quite desirable.

My battery's sitting comfortably at 40° F with 15° F ambient temps.