New 2009 i-MiEV Owner

[miggols99]

This is my first post, so hopefully this is the right place!

I bought a used 2009 i-MiEV here in Japan a few months ago for around 360,000 yen.
The main purpose was to use it as a second car for quick shopping trips etc.

Where I bought it, they told me I would be able to get around 100km of range w/o AC or heating, and I found the range remaining indicator showed a range close to that when driving economically.

However, after a couple of weeks of ownership, on the way to a charging station around 10km away, the car suddenly stopped less than halfway there with the RR showing around 12km - no turtle, just the exclamation mark in the car icon appeared. Had to get it towed to the closest charger!

I have come to the realisation that the last two bars are virtually unusable, as an experiment the other day I drove it down to three bars, parked up at home, then ran the heater on full until the battery gauge started flashing at two bars. I then found the exclamation mark in the car icon lit up again!

Another issue I have found is DC rapid charging to be unbelievably slow. The day I had to get it towed, I used a 50 kW rapid charger for an hour and I was still only able to get up to around 60%!

So, wanting to get to the bottom of this, I bought an OBDLink LX (took almost a month!) to see what kind of condition the battery is in.
I have only been able to get OBDZero to work properly - caniOn keeps disconnecting/reconnecting every 10 seconds or so.
I'm not really sure how to interpret the data though. If there's anyone out there that wants to take a look I can attached the various text files outputted by OBDZero.

The battery capacity shows as 28.5 Ah - that's not great right? Still trying to get my head around the technicalities!

 

[JoeS]

Hi miggols99, and welcome to the forum.

Sorry to hear about your experience.

Sad to hear about your battery - with that capacity you may be lucky to get even 60km out of it. Since both the RR and fuel gauge don't give you an accurate indication, I would first fully charge the car slowly from its depleted state and perhaps it will recalibrate the fuel gauge (and the resulting RR). As far as CHAdeMO, you may have one or more marginal cells inside your battery which are limiting your fast charging ability.

By all means please do post screenshots of your OBDZero files here. Check out this thread, as it is not as simple as attaching a photo to your posting:
http://myimiev.com/forum/viewtopic.php?f=13&t=1626&start=40#p39027

 

[miggols99]

Thanks.
And yes, I've found the actual usable range to be around 60/70km.
I do have a regular petrol car for long distance so the short range isn't too much of a problem, but I would like to see what's going on in the last few bars.

Here's some screenshots from OBDZero at around 80% SoC.

Is there anything I should be worried about?

Will post some screenshots at a lower SoC once I get the chance.

 

[miggols99]

Finally got around to running the car down to do a calibration charge.

So here's what happened:

3 bars: (!) in car mark appears
2 bar: turtle appears
1 bar: 12v battery mark + (!) in car mark. Won't go to ready. Heating disabled (SoC @ 17%)

After that, the battery cooler fan was running non-stop for about 5-10 mins or so and wouldn't accept a charge.
Once it turned off though I was able to initiate a level 1 charge.

A voltage difference between 2.72 and 3.68 isn't a good sign right??

 

[miggols99]

After about an hour on level 1, the voltages are back to looking fairly normal.
I wonder what would cause an issue like this?

 

[CZeroOwner]

If there's anyone out there that wants to take a look I can attached the various text files outputted by OBDZero.

Hi Miggols99 I'm also sorry to hear of your problems with the car. OBDZero is my app and I would very much like to look at the text files. Can you send a link to them. You can also send a zip to my email [email protected]. However your battery capacity is similar to other cars of the same age and mileage so I'm not sure I can help. It may be that one cell is bad and drops below a minimum voltage when accelerating.
FYI you can download OBDZero's user manual using this link: https://obdzero.dk/wp-content/uploads/2021/11/OBDZeroUserManual38.pdf

Cheers
David

 

[miggols99]

An update:

Just finished getting a dealer battery calibration done.
Took a little longer than expected as it seems the older models (2009~2011?) require the process to be carried out manually.

The result is very interesting though. A very poor SoH of 54.583% with cells at 26.2 Ah (OBDZero shows as even worse: SoH @ 46%, cells at 23 Ah).
My RR at 100% has dropped to a measly 62km (!!), but on the way home I noticed that both the battery gauge/RR gauge do not seem to change so unpredictably as before. Before the calibration my battery gauge behaved like so:

16 bars ~ 13 bars: Loose these bars after just 5~6 km
13 bars ~ 8 bars: RR would suddenly drop around 10 km after parking up and starting again
8 bars ~ 3 bars: Relatively stable
3 bars and less: Chance the car will stop suddenly, so I don't dare go this low!

Will have to see what happens at a lower SoC...

 

[CZeroOwner]

Hi

The result is very interesting though. A very poor SoH of 54.583% with cells at 26.2 Ah (OBDZero shows as even worse: SoH @ 46%, cells at 23 Ah).

Yes very interesting results! The most recent dealer measurement of the my battery showed 41 Ah while the car showed 38.4. The OBDZero measurement agreed with the car not the dealer. This was in January of this year. I believe the reason for some of the difference is that the dealer measurement was done indoors at 20o. While the car measures the capacity at January outdoor temperatures of less than 5o. The dealer does reset the car's measurement to the dealer measurement so you can expect the car measurement to decrease as it adjusts to the lower outside temperature.

 

[MickeyS70]

Hi there

By no means an expert when it comes to battery degradation but after troubleshooting CMU issues in my car I would say that your car’s cell reporting is working correctly.

Unfortunately that would mean what you are experiencing seems to be caused by the battery cells themselves.

Although owners have successfully replaced individual cells, performance did not really improve afterwards.

Another option is to replace the whole pack but again you may end up worse off as good, used packs are hard to find.

…

 

[miggols99]

(Slightly) good news!
Running the battery so low can be quite nerve wracking, but I was able to get the SoC to less than 15% - right around here the turtle mark appeared. Going much lower however the heater stopped working and the 12v battery light lit up like before.
Hoping this means that more of the battery capacity is actually usable. I will have to do a more thorough discharge by just leaving the car on at a lower SoC and seeing what happens from there...

 

[JoeS]

...I will have to do a more thorough discharge by just leaving the car on at a lower SoC and seeing what happens from there...

Leaving the car ON in READY at such low SoC is *interesting*, as the dc-dc is still keeping the 12v battery alive and the car's systems continue sucking down the main battery. :shock:

Do let us know what happens when the car eventually shuts down and what the results are when you charge the i-MiEV back up.

TIA for sharing your experimentation with us and hoping you get improved battery performance.