Low battery warning and LeafSpy kWh question

[Ihavealeafnow]

2020 SL+ with now ~13000 miles, nearly 3000 by me. Pretty new still to the leaf world, but I enjoy the car a lot. I have LeafSpy pro and I like the extra data. I’m trying to figure which SoC to trust between the dash and LeafSpy.

The car will get down to LBW at single digit percents on the dash in a pretty normal way. I have only done this twice. Both times have been on trips where I didn’t want to push it further and I had planned a charging stop in the right spot. It does drop range faster than expected on highway trips, but I also average 4.5+ m/kwh in my normal trips (which I assume the dash uses to predict things like 246 miles from 100% charge) and only 3.5 mi/kwh or worse on 70 mph highway driving, so I expect the range of maybe 180-190 comfortably (say 55 kWh at 3.5 mi/kwh)

Most recently I got 3.2 miles/kwh in hilly high (70 mph) driving, and a range of 158 miles from start to when I stopped, meaning I used 49+ kWh from the battery for the drive. At stop, car was showing 3%. LeafSpy still showed 18% for SoC and showed 10.5 kWh remaining. So which is correct? 10.5 kWh seems like a lot for a 3% dashboard reading.

I know I have one module that’s a little odd. At this low state it was still down ~70 my from max module and 60mV from avg. At full SoC it is down about 100mV, and gets as close as 30 mV when the pack is around 50%. At around 50% SoC LeafSpy agrees with the dashboard as well.

So, what can I expect if I keep driving on a LBW when LeafSpy suggests >10 kWh in the pack? Is the dashboard more accurate? Is the LeafSpy number based more on average modules than the weak one?

When I have better opportunity I’ll just test it, but I’m curious what people here think should happen.

Thanks!

 

[Chad E. Mo]

FWIW, I typically get 3.5mi/kWh at 65 mph at 50F (flatlander). It gets up to 4 in warmer weather, down to 3 in colder. I now have 40k miles on the odometer, SoH is 91% ish.

Do you L2 charge overnight? My position is that the pack balancing takes place at the end of the 100% L2 charges.

My opinion is that LeafSpy is more accurate for SoC, but the dash is more pessimistic at the low end, similar to the fuel gauge in a Uhaul (nanny-ish).

 

[nlspace]

one module that’s a little odd. At this low state it was still down ~70 my from max module and 60mV from avg. At full SoC it is down about 100mV,

This weak module is throwing off the data. The battery pack has only the capacity of its weakest cell. For safety and protection the cell voltages would be used for cut-off and turtle, but the average or total pack voltage may be used for the "fuel" gauge.

 

[sjpeters79]

I've got a 2019 Leaf SL 40KW with about 60k miles and I'm encountering some similar issues, it's reporting that I'm at 12% SOC on the dash but on Leaf Spy Pro, it's saying I'm at 52% SOC. I don't quite understand the discrepancy. It does say there is a bad cell (#65).

It seems to discharge fine up until 60% and then the range just evaporates until hit 20%. I'm charging it overnight using 120v plug, so it's trickle charging and gets to 80% in about 8-11 hours which is nowhere near 80% of the pack.

 

[Stanton]

It does say there is a bad cell (#65).

Once you confirm/observe this, all bets are off. Range estimates (and turtle) are unreliable until you replace the bad cell/module. I suspect the OP is experiencing something similar.
Been there, done that.

 

[Ihavealeafnow]

So I returned from my trip and had 26 miles on the dash with 12.8 kWh on LeafSpy. Drove my usual commute (only 15 miles round trip) and did some range testing this evening. I reached low battery at a bit under 9 kWh this time, I’d guess because of using a light foot on local roads rather than hilly highway. Reached 5 kWh before turtle mode. Bad cell was show 500 mv delta at this point. Rest of the pack is in the 3.4 v range. The next biggest delta is only 90mv while the bad one showing 500. The bad one showed around 50mv until it went below 3.3v then dropped basically like a stone.

Since I can only get a bit about 56.5 kWh at 100% charge, and turtle mode kicked on at 5kwh, I’d guess I just have 50kwh of useful range. Sucks. But now I know the number.

This really seems like a crappy way to hide battery problems. The SOH still shows 96%. Ha! Useful capacity is 80%. I’ll at least try complaining about range to the dealer.

 

[knightmb]

So I returned from my trip and had 26 miles on the dash with 12.8 kWh on LeafSpy. Drove my usual commute (only 15 miles round trip) and did some range testing this evening. I reached low battery at a bit under 9 kWh this time, I’d guess because of using a light foot on local roads rather than hilly highway. Reached 5 kWh before turtle mode. Bad cell was show 500 mv delta at this point. Rest of the pack is in the 3.4 v range. The next biggest delta is only 90mv while the bad one showing 500. The bad one showed around 50mv until it went below 3.3v then dropped basically like a stone.

Since I can only get a bit about 56.5 kWh at 100% charge, and turtle mode kicked on at 5kwh, I’d guess I just have 50kwh of useful range. Sucks. But now I know the number.

This really seems like a crappy way to hide battery problems. The SOH still shows 96%. Ha! Useful capacity is 80%. I’ll at least try complaining about range to the dealer.

My guess would be the battery already had damage and the BMS was reset to hide the damage (by previous owner or dealership). The SOH takes months to tick down, depending on how what many bad cells you have. As already mentioned by others, your range is only going to be as good as the weakest cells, so at-least you can find what the limits are to help you. The downside is the SOH is going to keep ticking down over time and it will speed up as the BMS learns how the bad cell is hurting the overall pack health. Given the age of the battery and it still has a ton of warranty left, your best best is to purposely cause a battery failure code and take it in to Nissan to get it documented and some warranty work done to either replace the bad cell block or get a new battery.

 

[Ihavealeafnow]

My guess would be the battery already had damage and the BMS was reset to hide the damage (by previous owner or dealership). The SOH takes months to tick down, depending on how what many bad cells you have. As already mentioned by others, your range is only going to be as good as the weakest cells, so at-least you can find what the limits are to help you. The downside is the SOH is going to keep ticking down over time and it will speed up as the BMS learns how the bad cell is hurting the overall pack health. Given the age of the battery and it still has a ton of warranty left, your best best is to purposely cause a battery failure code and take it in to Nissan to get it documented and some warranty work done to either replace the bad cell block or get a new battery.

I sorta agree, except the dealer I got this from was fantastic. Literally the best car buying experience I’ve ever had. I know anyone can hide anything, but that seems implausible. And other than the one cell, the battery seems great.

I’ve driven the car 3000 miles now looking at LeafSpy data a lot. I’ve only dropped 1/2% in that time. Over three months too, I see some data suggesting periodic “big drops” which I haven’t experienced.

The other cells are all well behaved. When I get around 20-25 % I can mash the throttle and never get more than 100mv. Not until in LBW on the car does it start to get bigger.

I’m going to complain to the dealer /Nissan purely about capacity. Something like- From full charge to turtle, averaging X kWh/mile I can drive Y miles, which represents 50kwh. From turtle to 100% I charge at ABC rate for XYZ hours, and the car reports to have gains 50 kWh.

Just need to look up the efficiency at 6.6 kw charging to back up that second part. I want the evidence to be as close to miles driven over kWh charged as possible.

Wish me luck!

Good news, this doesn’t change what I love about the car and I have enough range to reach Chademo stations on the trips I want to do a few times a year. I’d certainly be happier with an extra 30-40 miles, but such is life.

 

[FrancoVecchi]

Try to charge at low power at 100% some times, if the cell is only unbalanced and not so degradate, maybe it it will helps.

 

[nlspace]

I’m going to complain to the dealer /Nissan purely about capacity. Something like- From full charge to turtle, averaging X kWh/mile I can drive Y miles, which represents 50kwh. From turtle to 100% I charge at ABC rate for XYZ hours, and the car reports to have gains 50 kWh.

That's way too technical for anyone not intimately familiar with EV-speak, plus your ABC XYZ numbers won't mean didley-squat to a repair technician--he can only deal with the data, results and instructions of the Nissan Service Manual and Scan Tool.

You are trying to use common sense and intuition, but they deal in the land of written rules and procedures that must be followed--that's what they learn at EV school. They will have no clue about capacity as that is not a "thing" in the FSM, no DTC or wiring diagram, etc.

 

[knightmb]

I sorta agree, except the dealer I got this from was fantastic. Literally the best car buying experience I’ve ever had. I know anyone can hide anything, but that seems implausible. And other than the one cell, the battery seems great.

I’ve driven the car 3000 miles now looking at LeafSpy data a lot. I’ve only dropped 1/2% in that time. Over three months too, I see some data suggesting periodic “big drops” which I haven’t experienced.

The other cells are all well behaved. When I get around 20-25 % I can mash the throttle and never get more than 100mv. Not until in LBW on the car does it start to get bigger.

I’m going to complain to the dealer /Nissan purely about capacity. Something like- From full charge to turtle, averaging X kWh/mile I can drive Y miles, which represents 50kwh. From turtle to 100% I charge at ABC rate for XYZ hours, and the car reports to have gains 50 kWh.

Just need to look up the efficiency at 6.6 kw charging to back up that second part. I want the evidence to be as close to miles driven over kWh charged as possible.

Wish me luck!

Good news, this doesn’t change what I love about the car and I have enough range to reach Chademo stations on the trips I want to do a few times a year. I’d certainly be happier with an extra 30-40 miles, but such is life.

Having a good dealership relationship is a good first step. I would still take advantage of the warranty though. It's one thing to have a weak cell on the "depleted" end of the battery, but a bigger problem to have a weak cell on the "fully charged" end as this cell is going to cause you some future problems. As it weakens, the calculated range will be even more unreliable over time and cold weather will more than likely trigger your first turtle mode during normal driving, followed by more issues like the dreaded "EV can not start" dash error because the cell is so weak as to trigger the safety system that keeps you from starting one morning or might even happen during charging where you can no longer charge the Leaf.

I'm glad that you enjoy the Leaf and to keep your great experience going at least keep this in mind for the future. I'm not trying to throw any shade at your Leaf ownership, but I've read enough similar cases here from other Leaf others that had a good reason to rant here.

 

[Ihavealeafnow]

That's way too technical for anyone not intimately familiar with EV-speak, plus your ABC XYZ numbers won't mean didley-squat to a repair technician--he can only deal with the data, results and instructions of the Nissan Service Manual and Scan Tool.

You are trying to use common sense and intuition, but they deal in the land of written rules and procedures that must be followed--that's what they learn at EV school. They will have no clue about capacity as that is not a "thing" in the FSM, no DTC or wiring diagram, etc.

That’s unfortunate because it seems like a basic metric. But good tips. Has anyone had a successful strategy to deal with a weak module? Just need to get an error code?

 

[Ihavealeafnow]

Having a good dealership relationship is a good first step. I would still take advantage of the warranty though. It's one thing to have a weak cell on the "depleted" end of the battery, but a bigger problem to have a weak cell on the "fully charged" end as this cell is going to cause you some future problems. As it weakens, the calculated range will be even more unreliable over time and cold weather will more than likely trigger your first turtle mode during normal driving, followed by more issues like the dreaded "EV can not start" dash error because the cell is so weak as to trigger the safety system that keeps you from starting one morning or might even happen during charging where you can no longer charge the Leaf.

I'm glad that you enjoy the Leaf and to keep your great experience going at least keep this in mind for the future. I'm not trying to throw any shade at your Leaf ownership, but I've read enough similar cases here from other Leaf others that had a good reason to rant here.

All good. Leaves are prone to throwing shade anyway.

The future degradation is all I’m worried about. At the top of the charge it still seems ok. One module down 90mv. I’ll just keep taking care of it I guess.