How to conduct a pre-purchase inspection for used Leaf?

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maniacbug

Member
Joined
Dec 1, 2021
Messages
5
Location
Seattle, WA
Hi, folks. Our family is considering a 2015 Leaf as the first car for our 16-year-old new driver. Having bought many used cars, I've come to rely on a thorough pre-purchase inspection at a local mechanic. It's not cheap, but it sure beats buying a crappy car.

The problem is I don't expect the local shop to be able to expertly inspect the EV-specific components, especially the battery. So far, I've come up with these options. I'm curious how you folks tackle this problem generally, as well as any feedback on the specific approaches.

1. Have the local Nissan dealer conduct the pre-purchase inspection. Presumably these people will know the most about the Leaf.

2. Buy the Leaf Spy app and the recommended OBDII reader, essentially inspecting the battery myself. If I go this route, am I just looking for SOH? Perhaps looking at SOC before and after a test drive?

3. Search harder for a local shop who knows this stuff? (Bonus points if anyone here is in Seattle and knows anyone they'd recommend on the Eastside.)

Thanks!
 
Welcome to the forum.

1. Have the local Nissan dealer conduct the pre-purchase inspection. Presumably these people will know the most about the Leaf.

No! There are a few Nissan dealerships with knowledgeable staff. They are few and far between...


2. Buy the Leaf Spy app and the recommended OBDII reader, essentially inspecting the battery myself. If I go this route, am I just looking for SOH? Perhaps looking at SOC before and after a test drive?

Much better! You are looking for a high SOH (but not so high as to suggest a BMS reset to hide a degraded battery), and a voltage histogram showing no cells vastly lower than the rest This is expressed also as a difference in millivolts, or "mv." No more than 50-60 millivolts is best, but a good pack can have a higher difference if it is simply unbalanced. If it's over 100mv, the battery likely has one or more bad cells.

3. Search harder for a local shop who knows this stuff? (Bonus points if anyone here is in Seattle and knows anyone they'd recommend on the Eastside.)

Also a great option. How about it, folks? I know we have members from that area.
Here is my used Leaf buying guide: https://www.mynissanleaf.com/viewtopic.php?f=27&t=26662&p=538030
 
LeafSpy and an OBD2, you can do this yourself.

However, I have heard good things about EV Works on Bainbridge Island:

https://www.ev-works.com/nissan-leaf-battery-life-extension/

One of the shops I would consider to do a pack swap, if I can ever find a 40 kWh pack, in good condition, for a reasonable price.
 
Thanks so much for the thoughtful reply.

LeftieBiker said:
You are looking for a high SOH (but not so high as to suggest a BMS reset to hide a degraded battery), and a voltage histogram showing no cells vastly lower than the rest This is expressed also as a difference in millivolts, or "mv." No more than 50-60 millivolts is best, but a good pack can have a higher difference if it is simply unbalanced. If it's over 100mv, the battery likely has one or more bad cells.

Great, thanks. I'll put this on the checklist!

LeftieBiker said:

Your buying guide is excellent. Thanks for putting it together. I did review it thoroughly.

As an aside, I was really hoping to score a 30kWh 2016 Leaf, but they're out of my price range. That is, until I read about the problems described in your guide, and I'm thinking maybe late-cycle 24kWh are a safer choice.
 
maniacbug said:
2. Buy the Leaf Spy app and the recommended OBDII reader, essentially inspecting the battery myself. If I go this route, am I just looking for SOH? Perhaps looking at SOC before and after a test drive?
Having helped friends and family for nearly a dozen Leaf purchases over the years (4 of them for myself and wife), this is the best route. Nothing against Nissan but I have yet to encounter a dealership (except for the one that is next to the Nissan HQ itself) that has any actual Leaf tech, then that Leaf tech needs to have actual experience with the Leaf, not just book knowledge if you are going with option 1 on your list.

Otherwise, you are best to do it yourself. Sure, people look at tires, look under the hood/engine, look under the car, but for an EV, most of that means little to something that has so little moving parts or failure points. The biggest gripe for any new Leaf owner is getting burned on a BMS reset or bad battery that they had no way to look at when buying. It would be like buying an ICE with a leaky gas tank, sure it runs, but the mileage would be terrible (and dangerous for ICE anyway).

Once you get LeafSpy + OBDII reader, you can see most *everything* going on with the vehicle because not only can you check the battery health, you can check for EV codes to spot if the heater appears to be going bad or if the 12 volt battery is causing under-voltage errors, etc. So much more than a dealership will tell you and the salesperson won't know what the heck you are doing anyway, so they won't mind if you check out the Leaf under the steering wheel. :D
 
Thanks for the great info, folks.

alozzy said:
However, I have heard good things about EV Works on Bainbridge Island:
https://www.ev-works.com/nissan-leaf-battery-life-extension/
One of the shops I would consider to do a pack swap, if I can ever find a 40 kWh pack, in good condition, for a reasonable price.

This place looks amazing. I'll have to check them out.

knightmb said:
Having helped friends and family for nearly a dozen Leaf purchases over the years (4 of them for myself and wife), this is the best route. Nothing against Nissan but I have yet to encounter a dealership (except for the one that is next to the Nissan HQ itself) that has any actual Leaf tech, then that Leaf tech needs to have actual experience with the Leaf, not just book knowledge if you are going with option 1 on your list.

...you can check for EV codes to spot if the heater appears to be going bad or if the 12 volt battery is causing under-voltage errors, etc. So much more than a dealership will tell you and the salesperson won't know what the heck you are doing anyway, so they won't mind if you check out the Leaf under the steering wheel. :D

Super helpful, thanks. Good to know what I'm looking for. My plan is to be up-front with them that I'm going to run OBDII diagnostics on the car to check the battery, while still going to a shop for an inspection of the mechanical components.
 
Good. Do the battery check first, as there is no reason to have a car with a degraded battery inspected.

One other thing: when you read the State Of Health (SOH), be very suspicious if the battery seems like new, as that almost always indicates a BMS reset done to make the battery seem falsely good.
 
What's the best SOH anyone has seen on a 2015, original battery, not replacement I mean?
I have a family member with a 2015 SV that took good care of it and it's only down to 82% SOH last I checked. :)
 
maniacbug said:
Super helpful, thanks. Good to know what I'm looking for. My plan is to be up-front with them that I'm going to run OBDII diagnostics on the car to check the battery, while still going to a shop for an inspection of the mechanical components.

That knowledge alone will make the salesperson know you mean business :x , might make them sweat a little. It did when I was helping my wife buy her 2018 Leaf, I was all over that thing and looking through every stat possible in LeafSpy right in front of them. :lol:
 
knightmb said:
What's the best SOH anyone has seen on a 2015, original battery, not replacement I mean?
I have a family member with a 2015 SV that took good care of it and it's only down to 82% SOH last I checked. :)

There might still be a few PNW cars, where the OP is located, that legitimately have 12 capacity bars. But, like with your friend, those 2015s will be on the verge of dropping the first bar. Almost zero chance of a legitimate 90% or more SOH at this point.
 
Ok, here's the results. Really interested to hear what anyone thinks.

This is a 2015 SV with 51000 miles. VIN research shows that it was originally sold and registered in the same city where this dealer is, and where I live too.

I drove 36 miles, a mix of city, suburbs, freeways (60 and 70) and 1000ft hills which together well represents our daily life. I stayed at the speed limit at all times, but otherwise didn't drive very special. It was 38F outside. I ran the heater to 65F on the lowest fan setting.

LeafSpy reported SOH 93.41, SOC 95.5 at start of drive. SOH 95.77, SOC 42.2 at end of drive.
Battery histograms look pretty level to my very un-expert eye.

So yeah, 36 miles took off 53.3 SOC, meaning a theoretical maximum range of 68 miles in these conditions. <Sigh>

Does that SOH seem suspiciously high for an older car?

Battery Histogram Before


Battery Histogram After


Dash Before


Dash After


Detailed View After
 
I've never seen the SOH vary that much in one day, much less an hour. Something seems fishy unless you made a typo somewhere. I wouldn't be surprised if the capacity increased due to the battery warming up during the drive but I doubt that would cause a significant change in the SOH.

That said, the range seems reasonable for that SOH.
 
Thanks for looking at it.

It's possible that there's an algorithm difference between the lite version and pro version? The first screen was taken with lite. I hadn't yet
bought pro because I didn't know if LeafSpy would recognize the OBDII device. Once I realized that it did, I bought the pro version. (Wife was driving!) No typos in the numbers. You can click into the thumbnails and see the full screens.
 
I suppose it's possible but LeafSpy only reports what the car sends to the OBDII port. I don't know how much (if any) calculation is required to convert the raw OBDII output to SOH but I always assumed the SOH was just a number sent to the OBDII port. But I really don't know. Dala would probably know or Turbo3 (LeafSpy author).
 
The car is a 2015, only has 2 quick charge sessions (first would have been in the factory), and has lived in the cool climate of Seattle so the battery statistics do not surprise me. I have seen improvements in Leaf Spy parameters from driving if the car has not been driven for a while (but not as much improvement as shown in this post). As others have already noted, the estimated range from your test drive seems appropriate for the SOH.
 
It seems the battery has about +18 kWh of capacity going by the screenshots, but the rapid SOH changes tells me a BMS reset was done recently and the computer is quickly re-learning the capacity. Not a bad thing if the dealership did a firmware upgrade before selling it, that acts like a BMS reset also. If you want to speed up the learning process for capacity, run the battery completely out as far as you feel safe, then run the rest out by using the heater on high, windows down, etc. next to your L1/L2 EVSE. Get the battery as low as you can safely (shutdown even if you have the time to sit and wait in the Leaf), then charge it all the way back up to 100% and see what the maximum capacity LeafSpy will show you on the screen that has the tire pressure / battery temperature (4th screen I think). You will be able to use that to get a good mental estimate on range. I have a feeling the SOH readings are going to be all over the place until the computer has more time for you to drive it and learn the average battery capacity.
On the plus side, doesn't seem the battery is way out alignment for cell voltages, as it was only showing a 10mv to 11mv spread, pretty good actually. It doesn't seem to be killing the GOM with crazy high/low range estimates either (yet? :lol: )
Don't fret over LeafSpy SOH readings until it seems to stabilize somewhere. If you see the SOH decreasing or increasing 0.01% everyday, don't try to plot out a future graph, it is just unnecessary worry. It will stabilize at some point, especially with the cold weather, it will stop eventually somewhere along the way.
 
maniacbug said:
Does that SOH seem suspiciously high for an older car?
It does to me, but only because I have friends and family driving the 2015 model line and none of them are above 84% SOH, but we also live in a much warmer climate. From what I gather, this Leaf lives in a much cooler climate, so I would expect that with a little TLC, the battery would easily be +90% SOH, just wasn't expecting one as high at +95%. The rapid drop to 93.41% makes me think of a BMS reset, but that's only a bad thing when it's used to cover up a failing battery. It's completely possible that this battery will settle in and still be in the +90% range with decent capacity and usage as an EV.

As a more technical example, if you drive the Leaf all the way to battery shutdown and then charge it all the way back up to 100% but the computer only records 10 kWh of power going into the battery before it's full, you and the computer will know real quick about the battery capacity. :?
 
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