Posts: 69
Joined: Wed Oct 11, 2017 11:21 am
Delivery Date: 28 Apr 2018
Leaf Number: 310136
Location: Seattle, WA

BMS reset proof for dealership

Sun Mar 17, 2019 11:04 am

Yesterday I was helping an older friend shop for a new (to him) car, and so I wanted to show him a Leaf to compare with the Kia Soul and Honda Fit he was looking at. He was skeptical, but as soon as he drove it he was sold. Despite everything I had said about the Leaf in the past, he was still expecting a sluggish golf cart.

So, that was all fine, and after downgrading from an 2017 SV to an 2017 S we were able to get well within his budget, but I also was concerned about the battery. I hooked up LeafSpy, and read 79.16 aHr, 99.6% SOH, 92.04 Hx with 24,000 miles, 80 L3 and 363 L1/L2s. The nearly 100% SOH made me concerned that the BMS had been reset, so I insisted on talking with the service manager. Here things got frustrating, because she adamantly claimed that it was absolutely impossible to reset the BMS without replacing the battery, and anything I had heard to the contrary was false.

In the end, I decided that this Leaf was fine for my friend, since the 5% degradation shown by the aHr was probably realistic. But, does anyone have suggestions for good evidence I can point stubborn Nissan people to in the future? For those in Washington, this was at Tacoma Nissan.
2019 Deep Blue SL Plus

Posts: 3855
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: BMS reset proof for dealership

Sun Mar 17, 2019 11:36 am

The dealership is wrong.

Sorry to say, I suspect you gave your friend poor advice.
The way to handle these suspect cases is to either match miles driven to SoC fall over a longish test drive, or to head to a ChargePoint EVSE and match kWh delivered to SoC gained. Figure that ~ 12% of kWh delivered are losses that do not make it to the battery. If using a ChargePoint try to charge for at least an hour, preferably two.

These calcs are not exact but they are more than good enough to identify a battery reset.
2013 LEAF 'S' Model with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Car is now enjoying an easy life in Colorado
03/2018: 58 Ahr, 28k miles
11/2018: 56.16 Ahr, 30k miles
2018 Tesla Model 3 LR, Delivered 6/2018

Gold Member
Posts: 2087
Joined: Mon Nov 22, 2010 6:47 pm
Delivery Date: 12 Jun 2011
Location: Phoenix, AZ

Re: BMS reset proof for dealership

Sun Mar 17, 2019 7:30 pm

The AHr and SOH numbers are probably correct if the car has lived in the cool Pacific Northwest for its entire life.
Silver LEAF 2011 SL rear ended (totaled) by in-attentive driver 1/4/2015 at 50,422 miles
Silver LEAF 2015 SL purchased 2/7/2015

Posts: 5
Joined: Thu Jan 03, 2019 10:36 pm
Delivery Date: 05 Oct 2017
Location: VK3

Re: BMS reset proof for dealership

Mon Mar 18, 2019 8:04 pm

Extract from Nissan Service Bulletin

DO NOT “READ & WRITE” any Li-ion Battery Controller (LBC) data to the new HV
Battery Pack assembly.
Writing the old HV Batt ery Pack LBC data to the new HV Battery Pack assembly will
cause the vehicle to read only 8 bars of capacity and will require the LBC to be

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