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Bad battery. Finding out required detective work

34K views 131 replies 34 participants last post by  Meldev##44 
#1 ·
Yesterday I figured out that my battery is bad. I don’t know when it happened but it was sometime between March and August. In March we did a trip to the desert and the battery behaved as expected in both discharge (range) and charging at fast chargers.

Then over the summer I noticed that the range went to shits. 140 miles on a full charge; not the GoM though .. the GoM still thinks I have 230 miles even though I have been proving it wrong every day.

I started keeping track of all trips in August.

I thought that it was my driving. I kept track of kWh SoC as provided by WattCat. Indeed, I was churning through tremendous kWh, and the SoC *percentage* as reported by the car matched the kWh. [I calculated the correlation, WattCat’s kWh SoC correlates with car-reported SoC %age at R-squared of >0.99. There's a plot in another post.]

My consumption, even on totally benign, not-pushing-it, trips has been insanely high, by both reported SoC %age and kWh.

Yesterday I used a fast charger for the first time since March because I went up to the mountains and had to charge. I used it twice, once on the way up and once on the way down.

Here are the kWh added as reported by the charger (first number); the difference in kWh pre- and post-charging as reported by WattCat (second number); and the difference in percentage SoC pre- and post-charging as reported by the car (third number).

31.9 58.1 69%
38.7 63.7 74%

So: assuming no loss from the fast charger, my total battery capacity is:
31.9 kWh / 0.69 = 46.2 kWh
or
38.7 kWh / 0.74 = 52.3 kWh

(If you consider ~3% or so loss it's even worse)

And last night I did the same with my L2 charging cable, same story.

So: in contrast to @ThinAir (see the WattCat thread, page 4), in my case both the reported SoC %age *and* the reported kWh SoC is erroneous. (Not WattCat's fault, obviously, but the car's because it reports an incorrect value).

How is it possible that the car doesn’t report an error when the issue is this extreme?!?
 
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#4 ·
****. How many total miles do you have on the battery? I hope you can talk some sense into someone at your JLR dealership service department and get a new battery. It might be complicated if the car reports everything is fine which seems to be the case.



If you're able to see past the crappiness of the situation, it's very interesting data. This probably explains the wild consumption numbers you were calculating. I wonder how the car was coming up with the consumption numbers it was presenting. It may have somehow been compensating for the battery problem or it may measure the power it actually pulls from the battery instead of trusting the battery reported SoC. Not much seems straightforward about the I-Pace's software.



There seems to be a recent spate of reports of bad I-Pace high voltage batteries on forums. We're all warrantied for a long while yet, but I'm going to keep a closer eye on mine than I have been.


May your mitigation be swift, painless, and effective.
 
#5 ·
****. How many total miles do you have on the battery?
Just under 6000

This probably explains the wild consumption numbers you were calculating.
Yup, exactly.

I wonder how the car was coming up with the consumption numbers it was presenting.
Yup, exactly. Whatever the reason, the measurements it takes (or considers) are somehow incomplete, so under a certain failure regime that my battery has, it is blind to it. I'm hoping that a real battery diagnostic will reveal the issue, as it is quite pronounced.

May your mitigation be swift, painless, and effective.
Thank you!
 
#6 ·
I took my car into Jaguar and asked them to test the battery. Long story short I am getting a new battery. Great experience at the service desk at my dealership.

My experience underscores the need for EV owners to track battery performance so that they can detect problems early.
 
#9 ·
I used a different method to calculate my battery capacity which you may want to try.
I take the reported charge after charging and divide that by SoC after charging and get a good estimate of battery capacity.
That works for you because in your case the reported charge is correct. In my case the reported charge is incorrect (the second column), which is why it took me a while to figure out what's wrong.
 
#10 ·
Update:

Dropped off the iPace at JLR Livermore today. Got a Velar for a loaner (I'll post another thread for entertainment). Service guys think it may have to be escalated to JLRNA. Glad I did so much documentation, it's a bit of a hill climb to get people to not be skeptical. Overall good experience, everyone was professional and personable and spent quality time for discussion. I'm attaching the summary documentation I provided them with.
 

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#12 ·
Update:

Remote monitoring is a great thing. After the dealer installed all the software updates, the car now correctly reports the SoC in kWh. It is currently 30.8kWh at 69%, meaning that total battery capacity is about 45kWh. Almost exactly as I predicted with my analyses.

They are now talking to JLR daily. It's their first bad battery so they're learning. I've been asked for patience, which I do have as long as they keep pushing on it with JLR.
 
#13 · (Edited)
Update:


They are now talking to JLR daily. It's their first bad battery so they're learning. I've been asked for patience, which I do have as long as they keep pushing on it with JLR.
Hello everyone,

Yesterday Jag installed my new battery and thanks to remote monitoring I can see that I now have 85.1Kwh at 100% charge.

This is the second replacement the dealer has done and there finished ahead of schedule. You have to wait for the things, diagnosis, shipping of the new battery, installation and testing.

Once the battery arrives is a day to remove it, a day to install and charge it and another day to test it. So I'll have my car back in the next 24 soon.

I get the impression that this was taken seriously so keep your records to watch for battery degredation.

One last thing I believe that they can test for and replace individual cells but in my case of was a completely new battery.
 
#19 ·
there was a thread on the uk forum by some people who wanted to charge for it ... but i haven't seen anything about it lately, so i don't know if it actually exists (and i don't keep track of iOS things, being an android droid)
 
#24 ·
$60,000 for the battery??? That makes no sense and really kills the financial insentive of getting an EV. I calculated I'd save $30-40k going EV (with cheap Quebec hydro), but if that gets offset by $60k for a new battery (so $20k in the hole), it really hurts. I assume there will be other options (refurbished, 3rd parties etc...) but still, that is ridiculous.
 
#29 ·
Update:

Car has been at dealer since 9/23. Instead of replacing the battery pack they were instructed to perform surgery: take apart battery, replace individual cells. This is a nonstarter as far as I'm concerned. JRLNA got a nice letter from me today. Arg.
 
#30 ·
With that large of capacity loss, it is unlikely replacing certain cells is going to bring back the battery to a healthy condition. Other cells are probably weak but within limits. The problem becomes one of balancing for 100% available capacity, and reaching 10% across the array when discharging. Balancing will take far longer, and the range will be hit because the lowest cell is what determines discharge limit. You don't want to discharge any cell below spec for desired life.

That really bites that JLR is not controlling the quality of battery production adequately. Looks like we may be repeating what Nissan owners discovered.
 
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#32 ·
@McRat: it all depends on which cells and how they failed. In a bank, depending on configuration used on the I Pace (anyone know the layout?) one or two bad cells can essentially "bring down" the entire group. I wonder if depending on diagnostics and number of cells JLR decides to replace the battery or if its one or two bad ones do an onsite repair. Once the bad cells are replaced there should be no difference in performance or longevity.
 
#33 ·
Most of the 'pouch cell' style batteries have several modules, which are like individual batteries.
IIRC, our batteries are 36 modules, each hold 12 cells in a 3s4p configuration for pack of 108s4p = 432 cells.
 
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#43 ·
Since Nov.1 when we received the car back from the dealer with one cell replaced in the main battery and the software updated, the maximum charge available has been 94% even when our home charger indicates "fully charged". I have been told by the dealer that this is "normal" and will be corrected when we get the next software update. Anyone else have this with the latest software update?
 
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