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Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Fri Apr 06, 2018 1:45 pm
by LeftieBiker
If they can charge it to 100% before he leaves with it, and reset the trip meter and energy economy display, that should give you most of what you need.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Fri Apr 06, 2018 1:47 pm
by SageBrush
briscobully wrote:
SageBrush wrote:
briscobully wrote:I'm dying to get to that 2013 SL with the Feb 2013 build date and LeafSpy it! Is it possible that a Feb build with 26k miles realistically showing 12 bars still?
Possible ? Sure
Likely ? I think not

LeafSpy will not clue you in to a reset. Only a decent range test drive* (say, of at least 30 miles) would let you sort out the real battery health.


*
Reset the trip meter for the test drive. This will also show you the consumption rate (in miles/kWh) for the test drive.
kWh = 1/consumption rate * distance traveled
Compare the SoC drop of the test drive to the kWh consumed. A battery in good shape drops less than 5% SoC per kWh
So I may have convinced the sales rep to bring the car to me (long story) is there anything I can have them do that will help me with testing the battery as explained above? He's got about a 20 mile trip to me and don't know if I will have time to do another 30 miles to check it out. Thx
Note the SoC and reset the trip meter at the start of the trip (leaving the dealership)

Do you understand the rationale of the test ? I can try to explain it differently.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Fri Apr 06, 2018 7:14 pm
by briscobully
Sagebrush

I do understand the test but can I rely on the car's SOC value as i won't be leaving the dealership with the car. I'll have to rely on the rep/dealership to fully charge and reset the values on the car before he brings it to me.

Should I do or work a different calculation in this case? Thx

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Fri Apr 06, 2018 11:53 pm
by LeftieBiker
You can use any SOC, as long as you know for sure what it is, and realize it will be within a full percentage either way. I figured having them charge it until it shuts off at 100% was the best way to guarantee a known starting charge.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Sat Apr 07, 2018 12:26 am
by alozzy
You can estimate the health of the battery fairly well by doing a short-ish range test:
  • Note the current state of charge (SOC) BEFORE you start driving
  • Reset the energy economy gauge and trip counter BEFORE you start driving
  • Drive on a highway, in good weather, maintaining 50 mph until the state of charge has dropped by 25% from the SOC you noted earlier
  • Get off the highway ASAP and note how many miles you drove and the energy economy reading on the dash
With the above information, you can estimate the kWh capacity of the battery:

Step 1 - Calculate kWh consumed by trip:

distance (miles)/efficiency (miles/kWh) = usage (kWH)

Step 2 - Calculate approximate pack capacity:

Since the above is the kWh usage for 25% SOC drop, 100% estimate would be just 4 times that #

For example, if you drove 20 miles over a 25% SOC drop and average 4.5 miles/kWh, then:

20 miles / 4.5 miles/kWh = 4.44 kWh consumed for trip

Then, multiply that number by 4 (i.e. 17.7 kWh) to get the estimated pack capacity in kWh.


Note that none of the above relies on LeafSpy data, which is why it's useful...

A brand new pack is around 21 kWh useable, so LeafSpy SOH should be about 84% in the example. If instead it was >90% then a BMS reset would be a strong possibility.

Having stated all of the above, a BMS reset on a 2013 would be pretty obvious anyways because virtually no 2013s are likely to have an SOH >90% at this point.

However, a used 2015 that was driven in a hot climate and had its BMS unscrupulously reset then exported across states, would be more likely to fool a potential buyer. That's because most 2015s in moderate climates would still have >93% SOH.

That's the purpose of a range test - to weed out BMS reset LEAFs.

FYI, before you buy any LEAF, make sure you know its history and where it was first sold. I personally would never buy a LEAF that lived out most of its existence in a hot climate - unless it was dirt cheap and very likely to qualify for a free replacement pack.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Sat Apr 07, 2018 3:55 am
by briscobully
Very thorough, thanks so much! Ill let everyone know the results.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Sat Apr 07, 2018 3:57 am
by LeftieBiker
FYI, before you buy any LEAF, make sure you know its history and where it was first sold. I personally would never buy a LEAF that lived out most of its existence in a hot climate - unless it was dirt cheap and very likely to qualify for a free replacement pack.
Or, better still, already had that new pack installed recently.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Sat Apr 07, 2018 4:12 am
by SageBrush
I appreciate the detailed instructions for the OP, but two comments:

The starting SoC can be anything really; you just have to know the value.
It does not matter how you drive, the car speed, etc. That is the point of knowing the consumption rate during the test.

For the test, if we know the distance driven, the SoC drop during the test, and the consumption rate during the test, we can calculate the capacity (in kWh) of a full battery. Nothing else is needed and no other variables matter.

Note though that this is not a perfect test for many reasons, the most important being that the LEAF gauges are not the best and SoC drop is not entirely linear. So the longer the test, the better. I view it as a good screening test to find battery resets.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Sat Apr 07, 2018 4:51 am
by GerryAZ
alozzy wrote:You can estimate the health of the battery fairly well by doing a short-ish range test:
  • Note the current state of charge (SOC) BEFORE you start driving
  • Reset the energy economy gauge and trip counter BEFORE you start driving
  • Drive on a highway, in good weather, maintaining 50 mph until the state of charge has dropped by 25% from the SOC you noted earlier
  • Get off the highway ASAP and note how many miles you drove and the energy economy reading on the dash
With the above information, you can estimate the kWh capacity of the battery:

Step 1 - Calculate kWh consumed by trip:

distance (miles)/efficiency (miles/kWh) = usage (kWH)

Step 2 - Calculate approximate pack capacity:

Since the above is the kWh usage for 25% SOC drop, 100% estimate would be just 4 times that #

For example, if you drove 20 miles over a 25% SOC drop and average 4.5 miles/kWh, then:

20 miles / 4.5 miles/kWh = 4.44 kWh consumed for trip

Then, multiply that number by 4 (i.e. 17.7 kWh) to get the estimated pack capacity in kWh.


Note that none of the above relies on LeafSpy data, which is why it's useful...

A brand new pack is around 21 kWh useable, so LeafSpy SOH should be about 84% in the example. If instead it was >90% then a BMS reset would be a strong possibility.

Having stated all of the above, a BMS reset on a 2013 would be pretty obvious anyways because virtually no 2013s are likely to have an SOH >90% at this point.

However, a used 2015 that was driven in a hot climate and had its BMS unscrupulously reset then exported across states, would be more likely to fool a potential buyer. That's because most 2015s in moderate climates would still have >93% SOH.

That's the purpose of a range test - to weed out BMS reset LEAFs.

FYI, before you buy any LEAF, make sure you know its history and where it was first sold. I personally would never buy a LEAF that lived out most of its existence in a hot climate - unless it was dirt cheap and very likely to qualify for a free replacement pack.
Based upon my experience with both 2011 and 2015, the dashboard instrumentation is not accurate enough to make these calculations definitive. The calculations will give information to compare with data obtained through other means.

I suggest you have the dealer charge the car fully and reset all of the trip displays on the dash (both trip odometers, mi/kWh, average speed, and distance/time). Ask the sales representative to step through and write down all of the display information along with SOC bars (should be 12), battery temperature bars, ambient temperature (from eyebrow display), time (from eyebrow display), and odometer immediately prior to departure. Write down all of these same readings when the car arrives (do not reset any of them) and take Leaf Spy readings. Let Leaf Spy log data while you drive (if you have the Pro version), take as long of test drive as you can, write down all readings from the dash, and take Leaf Spy readings. Then post the data here for help with interpretation. This method will give three data points to compare (two trip segments and the overall trip).

Edited to add: As Sagebrush noted, the dashboard instrumentation is not necessarily linear. That is why I recommend not resetting the displays so that you have data from one long trip and two shorter segments.

Re: 2013 Leaf SV losing battery capacity checked with LeafSpy lite

Posted: Sat Apr 07, 2018 9:13 am
by briscobully
LeftieBiker wrote:
FYI, before you buy any LEAF, make sure you know its history and where it was first sold. I personally would never buy a LEAF that lived out most of its existence in a hot climate - unless it was dirt cheap and very likely to qualify for a free replacement pack.
Or, better still, already had that new pack installed recently.

Question. Will a new battery pack 'always' show up on a carfax report or only in a service history? I've see lots of carfax reports show recall work on many occasions...