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After my battery was 'fixed' by the dealer in December I ran a bunch of measurements and things seemed fine given that I wouldn't be owning this car in a couple of months. Its maximum capacity was at about 95% of new, which was good enough for the time being.

Well, the buyback process is dragging out and so I decided to run a few more measurements this past week. Hmmm. After two months and another 1500 miles of spirited but not insane driving, at mild CA winter temperatures and battery temperatures consistently between 50 and 70 F, the battery lost another 5% of capacity and the SoH is now at 90%.

All measurements were done with an OBD tool that's in beta testing and should be available to all of us soon. Check out the graph and results if you want to know the gory details.
 

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After my battery was 'fixed' by the dealer in December I ran a bunch of measurements and things seemed fine given that I wouldn't be owning this car in a couple of months. Its maximum capacity was at about 95% of new, which was good enough for the time being.

Well, the buyback process is dragging out and so I decided to run a few more measurements this past week. Hmmm. After two months and another 1500 miles of spirited but not insane driving, at mild CA winter temperatures and battery temperatures consistently between 50 and 70 F, the battery lost another 5% of capacity and the SoH is now at 90%.

All measurements were done with an OBD tool that's in beta testing and should be available to all of us soon. Check out the graph and results if you want to know the gory details.
Hi,

Can you describe the measurements? Are they spot measurements during a charge (and/or drive), or are they individual charge values (∆ SOC vs. ∆ kWh charge) over multiple sessions? I am about to take a multi-day road trip from Montreal-Boston-Albany-Toronto-Montreal and plan to record some data. I will try to log SOC and km at the start and end of each trip, the average consumption (as reported by the car), the energy put in during a charge (if the charger reports it) and the change in SOC from that charge. I have been trying to estimate the battery capacity by looking at the ∆SOC vs. consumption but the results are quite variable (but maybe I was sloppy in the data gathering).
 

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They're spot measurements provided by the OBD port. The battery capacity from the API data that WattCat accesses is massaged somewhat, but it's close to accurate (optimistic though). And I have not tried to assess the accuracy of the trip meter consumption figures lately, but when I did a while ago they seemed off by a bit too.

Be aware that the car can't report anything to the API if you're outside of cell phone coverage and the data displayed by WattCat will be old if you are.
 

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They're spot measurements provided by the OBD port. The battery capacity from the API data that WattCat accesses is massaged somewhat, but it's close to accurate (optimistic though). And I have not tried to assess the accuracy of the trip meter consumption figures lately, but when I did a while ago they seemed off by a bit too.

Be aware that the car can't report anything to the API if you're outside of cell phone coverage and the data displayed by WattCat will be old if you are.
I’m an Apple guy so no WattCat. If I only had time, I’d write an iOS version...
 

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After my battery was 'fixed' by the dealer in December I ran a bunch of measurements and things seemed fine given that I wouldn't be owning this car in a couple of months. Its maximum capacity was at about 95% of new, which was good enough for the time being.

Well, the buyback process is dragging out and so I decided to run a few more measurements this past week. Hmmm. After two months and another 1500 miles of spirited but not insane driving, at mild CA winter temperatures and battery temperatures consistently between 50 and 70 F, the battery lost another 5% of capacity and the SoH is now at 90%.

All measurements were done with an OBD tool that's in beta testing and should be available to all of us soon. Check out the graph and results if you want to know the gory details.
A couple of questions.
1. These numbers for charging are energy delivered compared to the reported increase in the SoC?

2. What were the average temps in Dec vs Feb. Here on the east coast we had colder weather in Dec than Feb. Does ambient temp effect the energy actually added to the battery vs the energy transferred thru the charger?

Have you had H264 performed on the car? I have only kept track of energy added vs SoC since my update and for me 1kWh added equates to 0.96% SoC vs your numbers of 0.85% (Dec) and 0.80% (Feb).
Just to throw out so ideas. Rather than battery health could these numbers represent inefficient charging due to factors such as heat generated, cooling systems running excessively, or other background energy use while charging?
 

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A couple of questions.
1. These numbers for charging are energy delivered compared to the reported increase in the SoC?
If you mean that they were supplied by the charger, no ... they're read from the car's computer via the OBD port with a dongle and represent the SoC of the battery in % and kWh (at different time points, which are not shown).

2. What were the average temps in Dec vs Feb. Here on the east coast we had colder weather in Dec than Feb. Does ambient temp effect the energy actually added to the battery vs the energy transferred thru the charger?
No issue with the temperatures .. battery was always between 50 and 70, no difference between Dec and Feb

Have you had H264 performed on the car?
No and I'm very glad you mention it. It will be interesting to see how the SoC behaves under H264. The OBD app will soon be available for all of us and it'll be great to have readings from multiple cars.

I have only kept track of energy added vs SoC since my update and for me 1kWh added equates to 0.96% SoC vs your numbers of 0.85% (Dec) and 0.80% (Feb).
Just to throw out so ideas. Rather than battery health could these numbers represent inefficient charging due to factors such as heat generated, cooling systems running excessively, or other background energy use while charging?
Nope. No other systems running, same charger, same result for charging and discharging (driving).
 

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Thanks for the detailed response. I wasn't trying to challenge your conclusions, rather just to understand the data, its source and any variability. Your battery does seem to be "bad". The question or direction I would be interested in going is "why?" If this were a design flaw in the battery, perhaps we would all be seeing something similar - in which case JLR has a massive warranty issue on their hands. Something tells me this is not the case.
Conversely, if this were a quality control issue with the battery wouldn't we expect to see bad cells rather than uniform degradation of the battery?
Have the service techs addressed any problems with the battery management system? I could imagine your issues being specific to your car if for example the cell balancing was not being performed correctly, or the temperature balance was faulty.
It is a shame to see some of the earlier forum members - especially those who were so enthusiastic about the car when it was introduced - having long term terminal problems.
 

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Oh, no worries! Asking critical questions is key in my business :)

And you're absolutely right that we have no idea why it behaves this way. I'm hoping that once I have a new car with H264 (or H280 ...) these issues will go away.

That said, it's basically impossible for most owners to conduct these types of analyses and I would not be surprised if some of us had slightly degraded batteries where it's not yet noticeable in daily use.
 

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Reading back thru a thread "Slow charging on a 7kW ...." I noticed you stated intermittant charging issues where your L2 charger would drop to approximately 1/2 power while the battery was nowhere near fully charged. Does this suggest that your software/hardware were not dealing with the heat generated during charging?
Just trying to be helpful, however your battery issues are intriguing. (Frustrating may be your word)
 

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Reading back thru a thread "Slow charging on a 7kW ...." I noticed you stated intermittant charging issues where your L2 charger would drop to approximately 1/2 power while the battery was nowhere near fully charged. Does this suggest that your software/hardware were not dealing with the heat generated during charging?
Just trying to be helpful, however your battery issues are intriguing. (Frustrating may be your word)
NB: That post was when I still didn't know that my battery was bad. In retrospect, this probably was the BCM "noticing" that something was wrong and going into some balancing or whatever regimen.

Funny you should mention it though, because yesterday I plugged in my ChargePoint L2 at ~50% SoC, and it reported the standard charging rate. However, the car (recorded via the OBD port) wasn't accepting the full charge rate and slowly crept up from about half the rate over the course of hours to the full rate. Clearly the car does some stuff that we don't understand. Furthermore, at the end of all that, my final capacity was increased compared to the last time I charged.

I'm not on H264 yet and I suspect I'm still chasing the bugs that they worked out in H264. I can't wait to get that new car so I can see whether this behavior has changed!
 

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FWIW, I have H264. I've looked at WattCat's API retrieval of battery capacity when I've fully charged it. The numbers have been up and down like a yo-you between 80 and 85.7kWh.
The very first time, after H264 it showed only 81% and once at the high end after charging at a 50kW charger. It only went to 84.3kWh after driving home from the 50kWh charger and charging at home, allowing the balancing act to be performed.

H264 may have some creative math in it for reporting numbers. Around here the temperatures have been like a yo-yo too so I'm pretty sure it is taking into account battery temperature and possibly a predictive environmental temperature factor.

Even charging with my Juicebox Pro 40 to 100% does not produce a nearly consistent capacity. The car is in a garage during this charging and the environmental temperature doesn't fluctuate as much as the external temps.

I don't know that we can ever figure out battery degrading until it gets to the point of being obvious (e.g. not going at least 150 miles on a charge in any condition).
 

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Have you already ordered the replacement car? Did you change any specs?
Nope, dealer wants to wait until I have a check in hand and that makes sense because we'll go with inventory. Not changing any specs, which probably puts me into HSE territory because I had loaded up my first one with performance seats and drive assist features ... you can bet I'll be checking the battery of any candidate car ...

FWIW, I have H264. I've looked at WattCat's API retrieval of battery capacity when I've fully charged it. The numbers have been up and down like a yo-you between 80 and 85.7kWh. The very first time, after H264 it showed only 81% and once at the high end after charging at a 50kW charger. It only went to 84.3kWh after driving home from the 50kWh charger and charging at home, allowing the balancing act to be performed.

H264 may have some creative math in it for reporting numbers. Around here the temperatures have been like a yo-yo too so I'm pretty sure it is taking into account battery temperature and possibly a predictive environmental temperature factor.
Yes, the API numbers are massaged. I'm not sure exactly how, but there is some "creativity" going on ...

I don't know that we can ever figure out battery degrading until it gets to the point of being obvious (e.g. not going at least 150 miles on a charge in any condition).
There will be an OBD app soon ... it will be worth every penny.
 
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