Phoenix Range Test Results, September 15, 2012

[turbo2ltr]

I would love to compare mfgr date of the battery modules. I just can't believe the 2012s are so low. It would also explain the fact that so many people lost a bar within a few months, somewhat regardless of the length of ownership, miles driven, and charging behavior. (all of which I believe also play a factor)

[WetEV]

I don't trust that "Gids" or capacity bars are accurate. Is there a reason to?

I agree, they are not accurate. However, the values are not random. We see good evidence that there is a systematic bias that under reports the available range. Thus it is reasonable to infer that a Leaf with 100% Gids would have at least 100% of the "New Leaf Range". I can't state it any more plainly than that. Testing a Leaf with 281 Gids is the only way to prove this inference correct.

The correlation between range and Gids in this test is ~80% (note: sample size too small). So yes, the values are probably not random, but that can't be completely excluded. There is also likely one or more other factors, the exact type of which is unknown. We see underestimated available range, but the odds that Gid count might overestimate available range are not negligible from the data in this test as the sample size isn't large enough. Testing a new Leaf that also has 280+ Gids would give a single point to determination of the "New Leaf Range", and ideally enough such tests would be run to get a sample size large enough to draw inferences that had statistical meaning. This test isn't large enough, and testing a single new Leaf also isn't large enough to be statistically meaningful.

Sorry, I'm an engineer. It is easy read too much out of too little data, and see things that don't hold up when more data arrives. It is important to get enough data, and to realize that the situation is often more complex than anyone might first think it is.

[shrink]

Sorry, I'm an engineer. It is easy read too much out of too little data, and see things that don't hold up when more data arrives. It is important to get enough data, and to realize that the situation is often more complex than anyone might first think it is.

While we all acknowledge the N is small, please keep in mind the logistical challenges of running this test. Tony cannot be thanked enough. A lot of attention was also given to safety and picking up the turtled cars as fast as possible. While far from perfect lab conditions, it was an excellent sample of real world driving.

That said, this small N was also double the N of Nissan's own Casa Grande 6.

[shrink]

Oh and for all those wondering, my car was Blue 842, the 2012 with 2500 miles on it.

I drove White530 and per the dash, I got 4.0 miles/kWh.

[WetEV]

Sorry, I'm an engineer. It is easy read too much out of too little data, and see things that don't hold up when more data arrives. It is important to get enough data, and to realize that the situation is often more complex than anyone might first think it is.

While we all acknowledge the N is small, please keep in mind the logistical challenges of running this test. Tony cannot be thanked enough. A lot of attention was also given to safety and picking up the turtled cars as fast as possible. While far from perfect lab conditions, it was an excellent sample of real world driving.

+1

That said, this small N was also double the N of Nissan's own Casa Grande 6.

Hmm... that raises all sorts of interesting questions.

[TonyWilliams]

we shouldn't expect that they will bother responding to the AZ Tempe test results at all, do we?

You can all fly up to San Francisco Crissy Field on Sept 23 (it should be gorgeous with the Golden Gate in the background) and meet the decision makers yourself. They will be there for National Plug In Day.

Andy Palmer (<<<-- probably not) and Mark Perry will be there, so you can ask them directly.

[evnow]

My suggestion is to release ALL the collected data.

As I have written in the past GID is not linear i.e. at the top & low end a GID has less energy than in the middle. That is the reason I stopped recording gids after every trip - and didn't post any definite conclusion from collected data.

The fact that 2 cars with 12 & 10 bars can have the same range points to faulty metering in the cars (even though the correlation of gid/bars to miles is high). Atleast it points to unreliable metering. That is the first thing Nissan needs to fix.

[Stoaty]

As I have written in the past GID is not linear i.e. at the top & low end a GID has less energy than in the middle.

In my two range tests, I found that Gids at the low end (15-25%) had more energy than the middle.

[edatoakrun]

Oh and for all those wondering, my car was Blue 842, the 2012 with 2500 miles on it.

I drove White530 and per the dash, I got 4.0 miles/kWh.

Thanks.

Using the reported gid count (assuming 85% was representative of the actual gid report error rate) to test for the same error rate on the nav screen (assuming you would have seen a reported 4.1 m/kWh there) I believe you would get a calculated ~22.8 kWh of available capacity for that car's battery pack, on that day.

The problem is, It was not a new battery, so you'd have to reduce that ~22.8 kWh figure by whatever was the correct % loss of capacity this battery had, from new to find the actual gid error % rate and derive the actual kWh capacity from that.

And since no one (apparently) tried to calculate the battery capacities of the test LEAFs, from any data source independent from the (erroneous) gid count, the actual gid error rate is now not calculable.

There is no real way I can see to verify this attempt at backwards analysis, other than to see how closely the unreported m/kWh report error rates from the other cars, match (or do not) the gid report error rates from the other test cars.

If consistent correlation is observed, we might be able calculate the actual available battery capacity, if we actually knew how many m/kWh these cars actually achieved, on the test.

But of course, if we actually knew the m/kWh, we would know the kWh capacity already...

Looks to me that if you want to know your LEAFs actual battery capacity, a meter or (accurate charge rate) and the charge efficiency, will be required.

If you want to know the range, be sure to charge as well as drive it in controlled range test, and you can ignore the capacity bars, and gid count.

[Volusiano]

we shouldn't expect that they will bother responding to the AZ Tempe test results at all, do we?

You can all fly up to San Francisco Crissy Field on Sept 23 (it should be gorgeous with the Golden Gate in the background) and meet the decision makers yourself. They will be there for National Plug In Day.

Andy Palmer and Mark Perry will be there, so you can ask them directly.

Any San Francisco local owner(s) volunteering to attend and question Nissan execs about what they think of the Tempe, AZ test results?

I suspect they would dismissively say they never saw it, or that they don't care to see it.

I think it'd probably be more effective if somebody can urge the media to ask them this question, in front of the cameras.