Best and Worst Case

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eyemgh

Active member
Joined
Oct 26, 2017
Messages
33
Location
Ashland, OR
I there a way to know best and worst case scenarios based on a good history and number of bars without Leaf Spy data?

Specifically, I found a '14 SL, original owner, mild climate, daily commuter, with 40,000 miles, but under 10 QCs and still with 12, I believe legitimate, bars. The guess-o-meter says 87 miles on full charge. I trust the seller. The car has a perfect record and was just given a clean bill of health, but of course with limited hard data, by Nissan today. It's 6 hours from me so I can't Leaf Spy it.

Given the miles, assuming no hanky panky with resetting the computer, is it possible to extrapolate best and worst case SoH, AHr and Hx from the history?
 
eyemgh said:
...Given the miles, assuming no hanky panky with resetting the computer...

I wouldn't grant that assumption. But if you do... The GOM is not useful for the kind of estimate you're looking for. If it truly is a 12-bar with 40K miles, then we could reasonably speculate that it is likely on the cusp of losing the first bar. Use the range chart(s) and plan for 11-bar performance. If you want better estimate you'll need LeafSpy readings, imho.
 
You should also verify what LeafSpy is telling you, as unscrupulous dealers can reset the BMS. An SOH of 95% or higher on an 2013/2014 is highly unlikely to be legit.

To do that, you need to do an extended driving test, using at least 25% pack charge, to verify the expected range. Lots of existing posts on how to do that...
 
Is anyone other than a Nissan dealer able to do a BMS reset? Remind me what the "legitimate" reasons for doing the reset are.

I would have thought that with a private seller who is the original owner, that would be pretty low on the list of concerns.

OP, has the seller described their use of the car in detail to you? I.e., do they mostly charge at home or at work? What town do they live in?
 
BuckMkII said:
Is anyone other than a Nissan dealer able to do a BMS reset?
Yes. See posts by AntronX in this thread, besides these posts:
http://www.mynissanleaf.com/viewtopic.php?p=489739#p489739
http://www.mynissanleaf.com/viewtopic.php?f=30&t=23714&p=489818&hilit=reset#p489818
http://www.mynissanleaf.com/viewtopic.php?p=489868#p489868

http://www.mynissanleaf.com/viewtopic.php?p=489807#p489807 before and after BMS reset.
BuckMkII said:
Remind me what the "legitimate" reasons for doing the reset are.
The only one is when the battery pack is changed.

I wonder who did the reset of the car mentioned at http://daveinolywa.blogspot.com/2014/11/buyers-beware-this-is-must-read.html and with what.
 
It’s been charged almost exclusively at home on L2. It has had less than 10 DCQCs. It has 43,000 miles and is still at 12 bars. I’m vetting it as though it’s full 11 bars. Given where it lives, its ownership history, how it has been used and communicating with the owner, I believe it’s very possible to still have 12 bars, very likely just though.
 
cwerdna said:
BuckMkII said:
Is anyone other than a Nissan dealer able to do a BMS reset?
Yes. See posts by AntronX in this thread, besides these posts:
http://www.mynissanleaf.com/viewtopic.php?p=489739#p489739
http://www.mynissanleaf.com/viewtopic.php?f=30&t=23714&p=489818&hilit=reset#p489818
http://www.mynissanleaf.com/viewtopic.php?p=489868#p489868

http://www.mynissanleaf.com/viewtopic.php?p=489807#p489807 before and after BMS reset.
BuckMkII said:
Remind me what the "legitimate" reasons for doing the reset are.
The only one is when the battery pack is changed.

I wonder who did the reset of the car mentioned at http://daveinolywa.blogspot.com/2014/11/buyers-beware-this-is-must-read.html and with what.

Thanks, I hadn't run across that before. So even LeafSpy can't catch the shenanigans.
 
Yup, which is why I always tell people the only real peace of mind comes from doing an extended driving test - reset trip counter, drive until SOC drops 25%, multiply trip miles by 4 to estimate full range. If the LeafSpy data doesn't jive with the estimated range (based on the empirical data), then walk away from the deal.
 
Not with the info you have. The GOM without miles per kwh is all but useless. and the MPK has to be reset every time the car is recharged. If its an SV, I think it has a history accessible from the center console (my 2011 SL had it anyway...) that would give you a somewhat better pix

but keep in mind a new pack can display 125 miles on the GOM at full charge quite easily so 87 is not very good.
 
Is the above a safe assumption? Maybe, more importantly, a drive to 75% SOC from full and multiplying by 4 should give a pretty accurate estimate of true range shouldn't it?
 
eyemgh said:
Maybe, more importantly, a drive to 75% SOC from full and multiplying by 4 should give a pretty accurate estimate of true range shouldn't it?
Range in a test drive is not the way to compare cars, since the driving conditions will not be standardized. What you really want to know is the pack's energy capacity, which is analogous to the fuel tank size in an ICE car. "Range" is simply the capacity (typically in kWh) times the specific "fuel" mileage you are seeing (in miles per kWh).

If you drove at a constant 90 MPH, your car's range would be MUCH less than if you drove at a constant 40 MPH because aero drag goes up with the square of speed. Similarly, if you were going up and down hills, with stops every block (think driving in Pacific Heights, San Francisco), your range would be less than driving in a flat region with few stops, because regeneration is not very close to 100% efficient. So, range in a test drive alone isn't going to tell you anything of much use for assessing the car's health. If the test driving conditions mimic your intended use very closely, I guess you would see how far you could go, but you would not know how "good" that car's battery is relative to others.

In principle, you can measure the pack capacity by the following method: reset all trip computers and energy histories on the dashboard and the center nav screen system. Shut off car and turn it back on to zero LeafSpy readings. Note the SOC % shown on the dashboard and in LeafSpy (which probably won't be the same, so record both). Start driving for as long as possible. You want to knock the SOC % down plenty. Fifteen to twenty miles of steady highway speed would be good; out and back along the same road so the vertical averages out but flatter is better so you don't have regeneration throwing off things. Stop and note the ending SOC % on the dashboard and in LeafSpy. Also read the mileage in miles per kWh from the dashboard or nav screen, and from LeafSpy (it's on the Summary screen, and you have to poke the little block of text above the colored bar graph several times to cycle through to it...take the Trip one with only one number, not the Charge reading with two numbers, one in parentheses.) Subtract the ending SOC from the starting SOC. Say they were 78% and 53%, so the difference is 25%. Divide that number by 100%, so the fraction of the battery you used was 0.25. Now, how much power did you use? Say you drove 19 miles at 3.9 miles per kWh. 19 miles / 3.9 miles/kWh = 4.87 kWh (energy consumed.) Divide that number by 0.25 and you get 19.5 kWh as the total capacity of the pack, which would be pretty good for a several-year-old car. I think my car holds abut 18.5 kWh, and it just lost its first bar.

I should say that, while this sounds good on paper, I'm not totally convinced it's foolproof to do this on one test drive and say you "know" the capacity of the pack. Mine actually got a better score on my first try!
 
The car is too far from me to Leaf Spy. I trust the owner. He has another EV, a solar array, and is enjoying the back and forth conversations about pack health. He in no way impresses me as a scammer. He's the original owner. The car has been driven on an ideal route and charged properly at home. It still has 12 bars, but we both suspect just, since it has 43,000 miles. We are trying to figure out how he can best verify the pack health, but I think he's just going to go get an OBD scanner and Leaf Spy it tomorrow now that he's familiar.
 
original poster is presenting an impossible question. You live 6 hours away and trust the seller.... YOU get the leafspy, drive the 6 hours and go test it...
 
It's a 2014 SL with Premium package, original owner, 12 bars, 43000 miles, 30 mile or so daily commuter, from a moderate climate, 15 DCQCs. We agreed to $10k and he's including an unopened Juicebox 40 Pro. So, effectively, I'm paying $9400. For that configuration, assuming of course no reset, it seems like a good deal. I missed the screamin' deal window that we had about 9 months ago.
 
Yeah, if the battery is really as described, buy it! That's a way better deal than I got. OTOH, I only had to drive 15 minutes to get to the dealer.

One dealer here is showing 3 x 2014 SLs for $12,995 asking. All from Bay Area and two of them with 11 bars. If the battery checks out, you're crushing it.
 
Agreed. Sounds like a really nice car for a good price. You could pay less for a lesser car, but I doubt you'll find an SL with premium package for less in that condition. Did you ever get the CarFax? Probably less of an issue if you're buying from the original owner.
 
eyemgh said:
Is the above a safe assumption? Maybe, more importantly, a drive to 75% SOC from full and multiplying by 4 should give a pretty accurate estimate of true range shouldn't it?

no because you can't use the bottom of the pack. Also the actual SOC measurements from the car is not super accurate.

Based on probabilities, you ;likely have a car that is within 83% to 90% of original capacity. You could be marginally less than that or as much as 5% more than that. How far that will take you is highly subjective. Some can go 85 miles during decent Summer weather, some would struggle to go 65 miles.

Keep in mind; depending on your cold tolerance, that range will be 15-30% less in Winter. Cold isn't as much of a factor (if you leave heat off) as rain on the roads so very hard to avoid in your area.
 
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