1 Year "Battery Check" Results

[TonyWilliams]

It has everyting to do with ambient temps. 5 minutes won't even begin to melt the ice on the windshield, 15 minutes is minimum useful duration here now. I've had to go to 20-25 minutes after the car sat for 4 days in 4 F temperatures.

I find that your thoughts earlier on my temperature corrections to range are correct.

So, I'm changing the temperature data to reflect:

Subtract 1% loss from range for each 4F/2C below 70F/20C

 

[kolmstead]

Wow, this thread took off!

First, a couple of comments. Regarding EVDRIVER's question, I am not sure whether 80% charging allows cell balancing or not. I think it does, because I see a couple of short cycles of charging on my TED after the car reaches my (usual) 80% charge. But, I have been charging to 100% once every month or two, just in case that helps. And Tony asked about priority. I have it set to favor charging over preheat. I agree with the comments that 25 minutes of preheat is too much; I was shooting for fifteen, but we got a slow start yesterday. I still don't know whether it caused any battery depletion.

Now, about today. Bad day. 45 or 50 degrees, rainy, 25 to 45 mph crosswinds. Not a good day to attempt an 85 mile drive.

Short story? 68 miles from 100% to immobile. The GOM said that I was screwed right from the start. I was down below 50 miles range before I even hit the hill below Rosamond. At the top of the hill, it said 35 miles remaining, and I still had about 65 to go.

Then it occurred to me that they probably updated the VCM firmware, although I asked them not to. That must be it! The GOM is lying to me. Total bars looked okay, and I was staying over 4 mpk.

Alas, the GOM wasn't lying. When I got in the car, I zeroed the trip meter and the mpk meter. But the display was in the 'time to charge' mode, so apparently the mpk meter didn't get zeroed, and I didn't notice that. It still reads 4.0 now...

My only consolation is that I am the first person to report watching his odometer roll over 10K miles... while driving in turtle. I have more pictures, but I think I'll split this story into two posts.

-Karl

 

[kolmstead]

I didn't make it. 66 miles to turtle, but I don't know what my real mpk was. Major crosswind. I hit LBW as I entered Red Rock Canyon and VLBW just before I got to the top of the hill exiting the canyon. Turtle just after the top of the hill. The last eight miles of range melted away in about three miles. To be fair, conditions were bad in the canyon. Moderate rain, and I hit a headwind. I actually saw the power meter hit seven bubbles once during a gust, versus three or four while climbing normally. No heat, of course; I had a blanket over my legs.

So, when I hit turtle at the top of the hill, I pulled over ASAP. Monika picked me up and we drove the remaining 20 miles home to pick up my truck and flatbed. When we got back to the LEAF, I started it and drove it two miles to where I'd parked the truck and trailer in a good spot for loading. As usual, the LEAF wasn't in turtle when I started it, and I was able to run 47 mph for most of the two (slightly downhill) miles to my truck. It was just starting to lose speed as I got to the truck. It had enough power left to turn on and off, and shift out of park into neutral. I see a power steering and 12V battery alarm on the display now. Those probably occurred while I was wrestling with the steering and winching the car onto my trailer. The PS alarm I can understand; the battery, not so much.

Not enough power left to drive on the trailer, so I winched it up. I collect antique tractors, so I am equipped to load dead vehicles:

And here it is parked under my sun shade, charging enough so I can get it off the trailer:

I probably won't try to drive to the Nissan dealer again.

I haven't checked the version of firmware installed in my car yet, so I don't know if they updated it. They did run a cell pair Voltage check, but unfortunately they waited until the car was 75% charged before they did it. And they failed to run the required battery use report. I'm covered, I think, since the work order clearly indicates that I asked them to do it. On the cell Voltages, the lowest was 4076 mV; the highest was 4116 mV. Battery Voltage was 394.3. What a shame; a check when the battery was discharged might have given them and us useful data.

My summary? I made some mistakes, and so did the dealer, so I still don't know how my battery is doing.

-Karl

 

[DaveEV]

Bummer about not making it, but I figured you didn't have a chance after yesterday with a slightly uphill drive today and worse weather today than yesterday.

68 miles seems a bit short with 4.0 mi/kWh - that's worse than yesterday in terms of available battery capacity.

Back to battery balancing - balancing at 80% is possible but more difficult to do accurately. Near 100% (or near empty) differences in charge level are more visible.

The reason the dealer wants the SOC low to do a detailed cell check is so they can see if any cells have significantly lower voltage than the rest. The check doesn't let them check overall battery capacity, only lets them identify weak cells.

 

[abasile]

I probably won't try to drive to the Nissan dealer again.

Kudos to you for trying, and I'm sorry the conditions didn't permit you to make it.

My only thought is, if you decide to try this again, could you possibly find a place to charge en route, in the town of Mojave? Granted, you'd probably want to charge at 240 V, so this would require a modified EVSE and possibly a Quick220.

 

[TonyWilliams]

68 miles seems a bit short with 4.0 mi/kWh - that's worse than yesterday in terms of available battery capacity.

Except, we don't know what his miles/kWh were, since it wasn't reset. Only that whatever he drove was averaged with previous trips to get 4.0.

Heck, that would only be 17kWh used total. Hills and wind are probably the culprit, with a hit for battery temp.

 

[DaveEV]

My only thought is, if you decide to try this again, could you possibly find a place to charge en route, in the town of Mojave? Granted, you'd probably want to charge at 240 V, so this would require a modified EVSE and possibly a Quick220.

Even this Chargepoint in north Lancaster would have gotten him to the dealer (nearly 10mi closer to Ridgecrest since the dealer appears to be fairly far south in Lancaster), though getting home will probably still be an issue. Mojave would be a good midway/stopping point, though 1-2 hours on L2 is a bit of a pain - but perhaps easier than towing it? If there were only a QC in Mojave...

 

[DaveEV]

68 miles seems a bit short with 4.0 mi/kWh - that's worse than yesterday in terms of available battery capacity.

Except, we don't know what his miles/kWh were, since it wasn't reset. Only that whatever he drove was averaged with previous trips to get 4.0.

Heck, that would only be 17kWh used total. Hills and wind are probably the culprit, with a hit for battery temp.

Whoops, misread that. Yeah, so his mi/kWh was well below 4, then. Absolutely no chance of making it.

 

[vegastar]

I haven't checked the version of firmware installed in my car yet, so I don't know if they updated it. They did run a cell pair Voltage check, but unfortunately they waited until the car was 75% charged before they did it. And they failed to run the required battery use report. I'm covered, I think, since the work order clearly indicates that I asked them to do it. On the cell Voltages, the lowest was 4076 mV; the highest was 4116 mV. Battery Voltage was 394.3. What a shame; a check when the battery was discharged might have given them and us useful data.

My summary? I made some mistakes, and so did the dealer, so I still don't know how my battery is doing.

-Karl

Very insteresting the cell voltage pair report. When the test was made the SOC was 75%? In my LEAF a total pack voltage of 394V is only achieved with a SOC of 100%. The difference between the highest and the lowest cell is 40mV. To give some perspective, the difference between 80% charge and 100% charge is 50mV, so that 40mV may be a large cell imbalance.

 

[kolmstead]

Yeah, I wondered about the variability seen reported. 75% is what the service guy estimated for SOC. I don't know if the test means much at that level of charge. I should have asked them to do it before they charged the battery at all, but they were more interested in getting the car charged up a bit so that they wouldn't have to push it around.

For Tony and drees, it seems to me that we can calculate my mpk for the return trip. Assuming that mpk didn't reset yesterday when I attempted to do so, the car had about 83 miles at 4.2 mpk from the day before, and then it died yesterday with an additional 68.2 miles on it, with indicated mpk of 4.0. So that's 151.2 miles at 4.0 mpk. I must have gotten 3.76 mpk yesterday for that to work out.

But that's even worse battery performance than my Friday trip. Friday was 83/4.2, or 19.8 kWh. Yesterday's was 68.2/3.76, or 18.1 kWh.

Based on the charging stopped messages I received, the dealer charged the car to 100% on Friday, and then had it on the EVSE for at least an hour Saturday morning, generating two more charging stopped at 12/12 messages. The battery should have been full.

I think it's time for me to invest in Gary's SOC meter! Too many unanswered questions.

-Karl

 

[KJD]

Very insteresting the cell voltage pair report. When the test was made the SOC was 75%? In my LEAF a total pack voltage of 394V is only achieved with a SOC of 100%. The difference between the highest and the lowest cell is 40mV. To give some perspective, the difference between 80% charge and 100% charge is 50mV, so that 40mV may be a large cell imbalance.

Really only 40mV cell imbalance. Hey I am no expert on Lithium by any means but when I did home built EV's I always considered anything less than 1/10 of a volt difference to be really good as in nothing to worry about.

On high voltage pack readings I have seen 4 different volt meters show 4 different readings with a spread of over 3 volts.

Does the Nissan service manual have any specs on cell imbalance high or low ranges ?

 

[TonyWilliams]

But that's even worse battery performance than my Friday trip. Friday was 83/4.2, or 19.8 kWh. Yesterday's was 68.2/3.76, or 18.1 kWh......The battery should have been full.

I think it's time for me to invest in Gary's SOC meter! Too many unanswered questions.

Those variations in cell voltages won't show up in the SOC meter, but you would have absolutely known that you weren't going to make it, and perhaps moved on to a plan B that might have found ANY power source to give you enough power to get home.

How many miles from LBW and VLB and then to Turtle ?

I have found that on the few times my battery has NOT delivered expected performance, it showed up at these two points. Generally speaking, you'll get about 50% of the distance from VLB to Turtle that you drove from LBW to VLB.

I have now had three occasions where there was what I believe a cell imbalance anomaly which significantly reduced the lower 15% of stored energy available in the battery.

After each anomaly, there was a 100% charge, and then 1-4 hours later, there was another short charge, presumably to top off the battery after the BMS has discharged the highest cell pairs. Then, the battery returned to expected performance below 15% SOC.

In one case, which required a tow truck, I only got 4 miles when I was expecting 8 miles between LBW and VLB. Using the 50% guideline, I knew that I'd only get about 2 additional miles when I normally would have gotten about 4. Sure enough that's when it coughed to Turtle.

In the worst case that I've recorded, I drove 2.9 miles from LBW to VLB.

I think the trigger to these events were numerous partial charges, without allowing a 100% charge followed by the required 1-4 hours to complete its cell balance routine. I would not now push the battery to its full calculated capacity without a 100% charge and either a 4 hour wait, or a text message that the battery has completed its second and final charge 1-4 hours later.

 

[edatoakrun]

...For Tony and drees, it seems to me that we can calculate my mpk for the return trip...

-Karl

Carwings does this for you, as well as reporting kWh Consumption and

Regeneration (correctly, only if you have CW updates) if you "accept" the on-screen prompt, when you start the car.

Go to CW "driving history", then "Electric Rate Simulation", to get m/kWh for any start/stop cycle(s).

My own LEAF has about a 2.5% constant CW "mileage driven" under-reporting discrepancy, so check the distance against your odometer and another source, for greatest accuracy.

 

[vegastar]

Very insteresting the cell voltage pair report. When the test was made the SOC was 75%? In my LEAF a total pack voltage of 394V is only achieved with a SOC of 100%. The difference between the highest and the lowest cell is 40mV. To give some perspective, the difference between 80% charge and 100% charge is 50mV, so that 40mV may be a large cell imbalance.

Really only 40mV cell imbalance. Hey I am no expert on Lithium by any means but when I did home built EV's I always considered anything less than 1/10 of a volt difference to be really good as in nothing to worry about.

On high voltage pack readings I have seen 4 different volt meters show 4 different readings with a spread of over 3 volts.

Does the Nissan service manual have any specs on cell imbalance high or low ranges ?

From 100% SOC to 17% SOC (LBW) the cell voltage varies from 4100mV to 3710mV or 390mV. So 40mV are more than 10% of that variation. Assuming a linear SOC/voltage relationship in this SOC range we can assume that 40mV represents 8.5% of SOC ((100-17)*40/390). So this really small difference can mean that the pack will give 8.5% less energy/range than a perfectly balanced one.

 

[kolmstead]

I haven't checked CarWings yet to see if it offers any insight. Haven't been there for months...

From Google Earth, it looks like about 8 miles from LBW to turtle. Roughly 1000 foot climb. I'm used to seeing LBW at about 18 miles of range remaining, but it was down in the single digits as soon as I glanced at the GOM.

I checked my firmware revisions today. Per my request, they didn't update my LEAF. So I'm still running "old bars" and the original, less pessimistic range estimator. I like it; it shows pretty much what I actually get.

I figured out why the PS and 12V battery warnings were on; I had turned on the car w/o pressing brake pedal when I took the picture of the display yesterday. They went out when I did a normal start.

-Karl

 

[TonyWilliams]

From Google Earth, it looks like about 8 miles from LBW to turtle. Roughly 1000 foot climb.

Was the 1000 foot climb during that 8 miles? If so, that's pretty good.

 

[edatoakrun]

I haven't checked CarWings yet to see if it offers any insight. Haven't been there for months...
Karl

You might find the large amount of additional energy consumption information available there, helpful in more precisely determining the effects of battery and ambient temperature, energy expended and regenerated in ascent/descent, etc.

Too bad the LEAF does not (yet) deliver the same info to the driver in real-time.

 

[Jimmydreams]

Service advisor mentioned he had seen one LEAF with only 11 boxes after 12k miles; no other details on that tho.

85% pack capacity after 12k miles is scary... What is the most miles driven by a LEAF with still 12 capacity bars? I have 9500 miles after 6 months, and I hope in my first annual battery check with 19k miles that I still have the full 12 capacity bars.

I've got over 18K miles on my Leaf and still all 12 battery bars. I have charged to 100% 100% of the time since I got the car.

YMMV.

 

[PDXLeafer]

I've got over 18K miles on my Leaf and still all 12 battery bars. I have charged to 100% 100% of the time since I got the car.
YMMV.

- I have been 'stress testing' the system also doing 100% charges 100% of the time, and plugging in right when I get home. I figure most people are basically lazy and will drive/charge this way unless there is a HUGE difference in performance. I have seen enough people doing the '80% charge, off-peak timer after batteries cool' so I went the other way.

I am only at 8400 miles though. My 1-year anniversary was Jan 18th, and had the service done that day. Nothing to report - '12 bars'

 

[Stoaty]

- I have been 'stress testing' the system also doing 100% charges 100% of the time, and plugging in right when I get home. I figure most people are basically lazy and will drive/charge this way unless there is a HUGE difference in performance. I have seen enough people doing the '80% charge, off-peak timer after batteries cool' so I went the other way.

I am only at 8400 miles though. My 1-year anniversary was Jan 18th, and had the service done that day. Nothing to report - '12 bars'

You are a braver man than I.

The problem with this approach is that you could have a 14% reduction in battery capacity, and the Leaf will still show 12 bars. I don't find 12 bars comforting at all (but of course 11 bars this early in the game would be very bad news). Nissan is hiding the early battery degradation from us so we really don't know where we stand.