Open Letter from Nissan, September 22, 2012

[scottf200]

The Volt's battery has as 40% reserve buffer that is never used, to extend battery life.. for all we know there may be Volts in Phoenix that have already lost some of that, yet the "usable kWh" display remains the same. My guess is that it will be a few years until that buffer is gone.

The Volt's SOC range is generally from 22% to 87% so 65% used. It can dip into the teens. (LEAF has 21kWh usage out of 24kWh so ~87.5%)

There has never been any proof or anything from GM that they ARE using any of that 35% as the battery degrades. If you have seen that then please provide the links!

I have seen one non-GM presentation from a battery company owner that indicated some of the 35% is used for "thermal management power requirements".

DrI's watching of the SOC via the PID does not show any degradation.
http://www.mynissanleaf.com/viewtopic.p ... 99#p232799" onclick="window.open(this.href);return false;

Dave an early Phoenix Volt owner watches his input to the the car and has not seen it changed. He has a solar system so watches kWs carefully.

From Rusty and DashDAQ

Here's how it maps between the gauge display and the actual battery SOC (or at least I think the VICM term is SOC).

Code: Select all

Battery Gauge  Gauge %     Battery %
10 bars        91%-100%    81.0%-86.5%
9 bars         81%-90%     74.4%-81.0%
8 bars         71%-80%     68.0%-74.4%
7 bars         61%-70%     61.5%-68.0%
6 bars         51%-60%     55.3%-61.5%
5 bars         41%-50%     48.7%-55.2%
4 bars         31%-40%     42.1%-48.7%
3 bars         21%-30%     35.6%-42.1%
2 bars         11%-20%     29.3%-35.5%
1 bar           1%-10%     22.7%-29.3%
0 bars          0%-1%      20.0%-22.7%

The ICE comes on around 20% SOC, and the CS SOC is around 22%. So the ICE runs a bit to bring the SOC back up from 20%ish to 22%ish. This somewhat confirms some of what we've heard about the battery and battery SOC.

[Herm]

There has never been any proof or anything from GM that they ARE using any of that 35% as the battery degrades. If you have seen that then please provide the links!

It was an old article by a GM exec back before the Volt was released.. that they would use the buffer to meet the 40 mile range spec as the battery aged. I have no idea if any Phoenix Volts have experienced degradation.. How could you tell by monitoring the kWh used during charging?.. the battery (unlike the Leaf) is never fully cycled.

[scottf200]

There has never been any proof or anything from GM that they ARE using any of that 35% as the battery degrades. If you have seen that then please provide the links!

It was an old article by a GM exec back before the Volt was released.. that they would use the buffer to meet the 40 mile range spec as the battery aged.

I don't think there has been any recent GM comments/presentations/etc and we are on the 3rd model year. 2013's went from 16 to 16.5kWh via chemistry tweaks and they use that 0.5 for more EV miles. Hence the 38 EPA rating vs 35. My 2011 has still gotten 45 miles + for the last 2 summers.

I have no idea if any Phoenix Volts have experienced degradation.. How could you tell by monitoring the kWh used during charging?.. the battery (unlike the Leaf) is never fully cycled.

I believe he watches his range as well as what goes in the car and both are consistent.

What about this? -->
DrI's watching of the SOC via the PID does not show any degradation.
http://www.mynissanleaf.com/viewtopic.p ... 99#p232799" onclick="window.open(this.href);return false;

What does the LEAF do with the 12.5% (100-87.5%)?

[TonyWilliams]

The Volt's battery has as 40% reserve buffer that is never used, to extend battery life.. for all we know there may be Volts in Phoenix that have already lost some of that, yet the "usable kWh" display remains the same. My guess is that it will be a few years until that buffer is gone.

The Volt's SOC range is generally from 22% to 87% so 65% used. It can dip into the teens. (LEAF has 21kWh usage out of 24kWh so ~87.5%).

Actually, LEAF stores 22.48kwh out of 24kWh advertised, and doesn't use the bottom 0.5kWh.

With losses, meter inaccuracies, etc, we typical see 21kWh useable at the wheels.

[davewill]

BUT I don't accept the inequality. Take a regular ICE car (like a Nissan Versa). Lets say the average life of the engine is 100,000 miles. If I drive 20,000 miles a year the engine only last 5 years, but that is my fault for driving so much. If someone else drives 10,000 a year it last 10 years. It doesn't matter if that person lives in Seattle, Phoenix, Dallas, New York, or Tampa Bay. If I drive 10,000 a year it will have about equal wear where ever I live.

But the leaf is different. 20,000 miles in Seattle does NOT equal 20,000 miles in Phoenix. ...!

I don't think that's true even for the ICE car. I'd expect the local climate to factor into the life of the car. Maybe not to the extent we're seeing, but it would definitely be a factor.

...His logic is flawed though since the length of the lease does not cover the life of the vehicle so while Nissan takes the initial burden once the lease is over either the original owner who buys the car or the next owner take on the rest of the risk. For Nissan to actually take on the risk of battery capacity they need to offer a real capacity warranty. ...

If the car is turned back in, the market should take battery health into consideration. I certainly wouldn't pay top dollar for an off-lease LEAF that has two battery bars missing.

[Herm]

]I believe he watches his range as well as what goes in the car and both are consistent.
What about this? -->
DrI's watching of the SOC via the PID does not show any degradation.
http://www.mynissanleaf.com/viewtopic.p ... 99#p232799" onclick="window.open(this.href);return false;

Ahh, I stand corrected.. the Volt does have a GID meter.

[leafkabob]

Here is a question that I would like for Hawk/Jeff Kuhlman to answer:
Is Nissan planning on releasing (or has it released) the Leaf in Dubai? If so, when? If so, will it have a liquid cooled BMS?
Thank you.

[TonyWilliams]

Here is a question that I would like for Hawk/Jeff Kuhlman to answer:
Is Nissan planning on releasing (or has it released) the Leaf in Dubai? If so, when? If so, will it have a liquid cooled BMS?
Thank you.

Here are some average temperatures:

....................Dubai.....................................Phoenix........

May: avg high 100F avg low 76F......ave high: 95F, average low: 69F
Jun: avg high 103F avg low 81F..... ave high: 104F, average low: 78F
July: avg high 105F avg low 86F.....ave high: 106F, average low: 83F
Aug: avg high 106F avg low 86F.....ave high: 104F, average low: 83F
Sept: avg high 102F avg low 81F.....ave high: 100F, average low: 77F

[scottf200]

Here are some average temperatures:

Code: Select all

...............Dubai...........|...............Phoenix............| Dubai-Phoenix 
May: avg high 100F avg low 76F | avg high:  95F, average low: 69F | avg diff +5
Jun: avg high 103F avg low 81F | avg high: 104F, average low: 78F | avg diff -1
Jul: avg high 105F avg low 86F | avg high: 106F, average low: 83F | avg diff -1
Aug: avg high 106F avg low 86F | avg high: 104F, average low: 83F | avg diff +2
Sep: avg high 102F avg low 81F | avg high: 100F, average low: 77F | avg diff +2

Those are ridiculously close. [use code to force monospace font and added avg diff col]

[TonyWilliams]

Here are some average temperatures:

Code: Select all

...............Dubai...........|...............Phoenix............| Dubai-Phoenix 
May: avg high 100F avg low 76F | avg high:  95F, average low: 69F | avg diff +5
Jun: avg high 103F avg low 81F | avg high: 104F, average low: 78F | avg diff -1
Jul: avg high 105F avg low 86F | avg high: 106F, average low: 83F | avg diff -1
Aug: avg high 106F avg low 86F | avg high: 104F, average low: 83F | avg diff +2
Sep: avg high 102F avg low 81F | avg high: 100F, average low: 77F | avg diff +2

Those are ridiculously close. [use code to force monospace font and added avg diff col]

It makes some of these statements seem odd:

Mark Perry, Director of Product Planning for Nissan North America. On August 3, 2012, he was reported to have said, "We've also been very transparent in making sure people know that battery capacity will degrade in very high heat – for instance, if the cars sit out in 110-degree heat for five hours a day." He was also quoted as saying sometime before January 25, 2010, "We don't need thermal management for the U.S., but we are looking at the technology for Dubai and other locations like that.... We've gone on the record saying that the pack has a 70 to 80 percent capacity after 10 years."