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I am beside myself with frustration. Yesterday I noodled the car down to 0%. Mind you, it was still driving ... it did not quit on me, so yes there was some battery capacity left. It was not at true zero. Nor does JLR tell you to Not Do That. I simply used what the car told me I had.

I will spare you the gory details but the bottom line is that during the following charging on my ChargePoint L2, the OBD-reported state of health dropped from 97%, where it had been consistently for the last 2000 miles, to 92%. My maximum charge is now 4.5kWh lower than it had been, and linear regression of the charging data also shows the same loss of capacity.

There was some cell balancing going on, so to double-check, I went for a drive to discharge some, and then charged again to full. Not much more cell balancing, same result: >5% less capacity now. This is freaking insane. A single discharge to zero damages the battery pack!
 

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What a painful lesson and thanks for letting us know about this issue. I'm sure that many other owners have unknowingly damaged their batteries and have read accounts of owners deliberately taking their car to 0% to test range. I hope that you can slowly bring back the capacity and health.

I haven't allowed my car to go below 20% due to a gnawing suspicion that it wouldn't be good.
 

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Not good. Hopefully this is not permanent. There are probably others on this forum who have gone down to zero. Has anyone else noticed this?
 

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Not good. Hopefully this is not permanent. There are probably others on this forum who have gone down to zero. Has anyone else noticed this?
I think it's very difficult to diagnose without an OBDII tool or asking the dealer to check battery health. I wish the API would report accurate health to WattCat again.
 

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I took mine down to something like 2 or 4% (whatever GOM 7 miles was at the time) last year. I charged it at a level 3 50kW charger to 100%. WattCat did show similar drop in the battery capacity (like down to 80kWh from 84-85kWh at 100%). Back then WattCat display a more accurate SOH too and it had dropped. Over time, with several charging periods at level 3 away from home and level 2 at home, the capacity "recovered." Right now, as it sits at 100% (post H280 install) it says 87kWh. I also found that (as you know) the ambient temperature, battery temperature, and even shutting it off in ECO mode instead of comfort mode makes a big difference in the charging results.

So don't get angry or panic just yet. Make your observations over the next month or so (assuming you drive and charge enough).
 

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What does the API gives for the 'EV_RANGE_VSC_REVISED_HV_BATT_ENERGYx100' and 'EV_RANGE_VSC_INITIAL_HV_BATT_ENERGYx100'. Is it different from what the OBDII gives ?
 

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I took mine down to something like 2 or 4% (whatever GOM 7 miles was at the time) last year. I charged it at a level 3 50kW charger to 100%. WattCat did show similar drop in the battery capacity (like down to 80kWh from 84-85kWh at 100%). Back then WattCat display a more accurate SOH too and it had dropped. Over time, with several charging periods at level 3 away from home and level 2 at home, the capacity "recovered." Right now, as it sits at 100% (post H280 install) it says 87kWh. I also found that (as you know) the ambient temperature, battery temperature, and even shutting it off in ECO mode instead of comfort mode makes a big difference in the charging results.

So don't get angry or panic just yet. Make your observations over the next month or so (assuming you drive and charge enough).
That's really good news!
 

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I've driven mine down to 1%-2% SOC a couple of times, and absent the reported (potential?) damage to battery state of health, would recommend new owners do so (near home) to develop a sense of how the car performs and behaves as you near 'empty'. It will help you NOT get freaked out at the 10% warning if you know how to initiate low battery mode and take range from ~22 miles to 30 or more when needed in a pinch. You also won't freak out when flooring it barely gets you up to 35mph when power is limited for that reason (slightly scary - and dangerous - phenomenon, until you know why its doing that). That said, now I'm very curious about the state of health of my battery. How do you see that?? Is it owner-viewable or do you need some 3rd party tool?
 

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Thanks guys for all the input and condolences ;) 🍺

Ayepace: yeah perhaps over a few charge/discharge cycles the SoH and capacity will creep up again. But that's why I drove to 82% and then charged again ... if it was short on balancing, it could have done that in the ensuing charge back to 100%, but it didn't. But I agree, it's conceivable that a few deeper discharge/charge cycles will being SoH back up some.

dtgsrq: yeah I too wanted to learn something, but it came at a price! Your post reminds me to make this point: if you never noodle it down to zero or close to it, you just don't know the range. I suspect that there is a mild memory effect even in Li batteries .. if you never deeply discharge, the batteries eventually don't have capacity at the bottom. Reminds me of the longest-mile Tesla Model X that had its battery pack replaced because after 200,000(?) miles it went from 40% SoC to empty in a jiffy. Furthermore ... it's not a single battery ... it's a pack. So when you noodle the whole pack down to 0%, perhaps a few cells take a bigger hit than others. (Which is why balancing is a thing.) So I would not be surprised if I have a couple of bad cells now that impair the function of a whole multicell module, decreasing overall capacity substantially.

dernotte: the numbers reported by the API are massaged. I can show by some basic statistics that the OBD values get tweaked by some nefarious software (dieselgate anyone? ;)) to always show you 100% (unless something is seriously wrong); and they even scale the kWh capacity, which I can show by correlating the OBD kWh with the WattCat kWh. It really smacks of deliberate obfuscation.

curt: haha, I challenge you to take it down to 0%! If you're chicken, take it down to 5%, which is probably ok. See how many miles you get from 20% to 5%, that would be useful to know!

🍺
 

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My battery capacity varies by more than a few% (as estimated using consumption and ∆SOC right after until right before charging). I get from ~75 to 85 kWh. Not sure how much is the variability in measuring consumption or how the battery efficiency changes with conditions. I think an n=1 or 2 is too soon make any conclusions.
 

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curt: haha, I challenge you to take it down to 0%! If you're chicken, take it down to 5%, which is probably ok. See how many miles you get from 20% to 5%, that would be useful to know!
Bawk, bawk, bawk... 🐔. Nobody here except us chickens... Lol. Maybe 10%?
 

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Sciencegeek, sorry to hear about this. I do agree with Ayepace and think you will recover some, if not all, of your lost capacity.

Coming from an MS, I never discharged close to 0%. That was always considered a 'no no'. I never understood the Tesla owners that were always trying to push the limits. Let Bjorg do that.

I've made it a habit of going down to only about 50 miles of range (roughly 20%) before charging. I don't trust doing deep discharges with these batteries, Jaguar, Tesla or any of them.

BTW, did you try recalibrating the GoM with the accelerator/brake procedure?
 

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@sciencegeek I am not convinced there is any damage. Taking battery all the way down may have added new calibration curve data for the pack into the mix, resulting in change in reported numbers. Whether it’s a “reveal” of the real state over time or a bad data bend it doesn’t mean it was from going down to 0, rather a reveal over time.

how many miles on your car?
 

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@sciencegeek I am not convinced there is any damage. Taking battery all the way down may have added new calibration curve data for the pack into the mix, resulting in change in reported numbers. Whether it’s a “reveal” of the real state over time or a bad data bend it doesn’t mean it was from going down to 0, rather a reveal over time.

how many miles on your car?
I'm with epirali. My money is that the system better understands the capacity now and you saw a shift in the guage as a result. I've seen this with cellphones on many occassions.
 

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Yes there's indeed a new transformation of SoC [kWh] to SoC [%], because the battery now has reduced capacity. The new calibration happened at the exact time point during charging that the SoH went from 97% (where it had been for 2000 miles) to 92%. This is the SoH that the dealer sees by the way, and upon which the warranty is based, not the incorrect number from the API (WattCat). The next couple of charge/discharge cycles will reveal whether that's the new normal now. I'm pessimistic that it will somehow fix itself.

I've done linear correlations between kWh and % for every single charge and discharge cycle since I've owned the car, taking 20-minute time points on the L2 charger and at every drive, and the curve fit had been incredibly stable at 87kWh usable capacity (and precise, with R^2 at 1) until that charging session where SoH went down.
 

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I am beside myself with frustration. Yesterday I noodled the car down to 0%. Mind you, it was still driving ... it did not quit on me, so yes there was some battery capacity left. It was not at true zero. Nor does JLR tell you to Not Do That. I simply used what the car told me I had.

I will spare you the gory details but the bottom line is that during the following charging on my ChargePoint L2, the OBD-reported state of health dropped from 97%, where it had been consistently for the last 2000 miles, to 92%. My maximum charge is now 4.5kWh lower than it had been, and linear regression of the charging data also shows the same loss of capacity.

There was some cell balancing going on, so to double-check, I went for a drive to discharge some, and then charged again to full. Not much more cell balancing, same result: >5% less capacity now. This is freaking insane. A single discharge to zero damages the battery pack!
Could temperature or other factor play a role and make it look worse than it is?
 
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