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LeafSwe
Posts: 32
Joined: Sun Jan 01, 2012 5:14 am
Delivery Date: 01 Feb 2012
Location: Sweden

Leafspy don't reflect true battery capacity

Mon Sep 11, 2017 12:29 am

I have done some testing over the Leaf years and used leafspy pro a lot. Have found that under some circumstances the numbers leafsy reports are way off.
I live in Sweden so summer temperatures are around 20 celcius and in winter -5 celcius average.

Example1 tested under year 2016.
2014 Leaf, build late 2013.
When the car was 2,5years old and with 60000km(37500miles) Leafspy showed ~67AHr and 100% SOH, way to good to be true, so i tested the range.
When i drowe this car i could get 120km range with consumption 150Wh/km from 100% to turtle, that gives exactly 18 kWh available energy @ battery temperature 20 Celcius

Example2 tested under 2017
2016 Leaf, build early 2016.
Now when the car is 1,5years old and with 20000km(12500miles) Leafspy shows 59AHr and 89% SOH, way to low to be true.
When i drive this car i get 133,5km range with consumption 150Wh/km from 100% to turtle, which gives 20 kWh available energy, battery temperature 20 Celcius

That shows that leafspy reports ~10% more energy than i can get in example1, and ~10% less energy than i can get in example2.

I think i found out why.
The 2014 Leaf was always driven on highway with high output by me, often with an average consumption of 200Wh/km(3.1miles/kwh)
The 2016 Leaf is driven very gently over the 12500miles by my wife on small roads with very low output, she often averages around 120Wh/km(5,2miles/kwh)

I have also tested how much power these cars draws from the outlet, and it shows the same result, about 10% more power goes in to the 2016 Leaf.

WetEV
Posts: 1738
Joined: Fri May 04, 2012 8:25 am
Delivery Date: 16 Feb 2014
Location: Near Seattle, WA

Re: Leafspy don't reflect true battery capacity

Mon Sep 11, 2017 7:06 pm

Leafspy is reporting on what the car's Battery Management System is estimating, not the true capacity.

I've seen similar increase in the same car by taking a long trip at higher speeds when the normal use is commuting at lower speeds and current draws. DCQC sessions seem to boost reported capacity in a small fashion as well.

Other people have reported similar.

I can speculate on why this inaccuracy exists, but as I can't change the BMS it is mostly pointless to speculate.
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
2012 Leaf SL Red (Totaled)
2014 Leaf SL Red

cwerdna
Gold Member
Posts: 7081
Joined: Fri Jun 03, 2011 4:31 pm
Delivery Date: 28 Jul 2013
Location: SF Bay Area, CA

Re: Leafspy don't reflect true battery capacity

Mon Sep 11, 2017 11:02 pm

WetEV wrote:Leafspy is reporting on what the car's Battery Management System is estimating, not the true capacity.
...
I can speculate on why this inaccuracy exists, but as I can't change the BMS it is mostly pointless to speculate.

And, whatever is being returned may have all sorts of caveats like a known error % of +/- some amount or might only be accurate in certain conditions or after certain things have happened (e.g. depth of discharge % then charge) or not happened. Or, these values that we're looking at may be intended to represent something else.

Nissan has AFAIK released no public documentation on the traffic on the CAN bus or any values that can be queried for.

viewtopic.php?p=497564#p497564 has a pointer to some posts about SOH and the former Hlth that became Hx. You may be able to read up on how folks discovered it there.

'13 blue Leaf SV w/premium package (owned)
'13 blue Leaf SV w/QC + LED & premium packages (lease over, car returned)
'06 Prius

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