Battery Design and Engineering Issues

[gasmiser1]

No room for 2 more modules on either side wilhout RISING the rear-passenger foot-space floor level.

I'm not so sure. Look at the photo below. Also, what if the actual production model appears with a flat rear floor?

This photo also shows why there isn't any storage space under the front passenger seat and driver's seats. I checked the Leaf out yesterday at Boardwalk Nissan.

 

[garygid]

The "chin-on-knees" riding position is not very comfortable for many.

I cannot even sit upright in the back seat as it is, due to lack of headroom.

I am only 6' 2" and I have about 1" clear headroom in the front, but
minus at least a half-inch in the back. So, my head has to tilt over
toward the middle of the car, thus quite uncomfortable for me.

 

[garygid]

In this picture, I expect that the floor and battery are
a bit "exploded" so that you can see the battery better.
I expect that there is essentially no "room to spare".

Over the modules would be the top of the battery pack, and then
maybe some airflow space between the top of the pack and the floor,
or perhaps some sound dampening material?

 

[indyflick]

The "chin-on-knees" riding position is not very comfortable for many.

The rear seat is called Stadium Seating because they have you sitting above the height of the front seats. I doubt raising the rear pan would put your chin to your knees.

 

[garygid]

Raise your feet about 3 inches and see where your legs end up.

Sure, the seat is "thick" and the carpet is "thin", but there is not
a lot of difference in elevation in there ... but more than I expected, ...
due to a "thicker" seat than I expected.

But, there is now insufficient headroom for me to sit there, ...
something like 2 inckes less headroom in the back than
in the front with the front seat all the way back.

One person mentioned that the front seat is Up/Down adjustable.
Not really, it is just on a fore/aft track that slopes up toward the front,
but no independent Up/Down adjustment like the 2010 Prius has.

 

[indyflick]

Maybe they could put in a couple viper-like roof blisters. :lol:

 

[AndyH]

But, there is now insufficient headroom for me to sit there, ...
something like 2 inckes less headroom in the back than
in the front with the front seat all the way back.

The good news is that Nissan has conveniently placed the steering wheel and pedals for use from the front seat. So unless you have another reason to be in the back... :lol:

 

[Jimmydreams]

But, there is now insufficient headroom for me to sit there, ...
something like 2 inckes less headroom in the back than
in the front with the front seat all the way back.

The good news is that Nissan has conveniently placed the steering wheel and pedals for use from the front seat. So unless you have another reason to be in the back... :lol:

My thoughts exactly. I rarely have anyone in the back seat, and if I do, it's for a short period of time and I apologize for the discomfort. No one has asked yet to get out and walk!!! :lol:

 

[AndyH]

Do we have ANY info yet on how, when, or how often Battery Cell balancing will be done?

We assume, if it exists at all, that it must be some form of "top" balancing, right? ... Because many (most) will "never" drive until their LEAF's battery is "empty".

"We" consumers don't need to know about balancing, think about balancing, or care about balancing.

Top balancing as used by the DIY management systems is not an option because the car won't let us touch the top or bottom 10%.*** LiMn has a more sloped charge/discharge curve - closer to lead acid than LiFePO4 - so it'll be easier for a computer to track general state of charge for individual parallel cell groups. Cells can be monitored for balance anywhere in the charge/discharge process and off the shelf hardware exists to do that.

edit... ***
This is a bit too general. It is very possible to balance lithium at any point in the curve, and they can be 'top balanced' at the 80% SOC mark easily. But I stand by the message that no Leaf owner needs to think about balancing in any way as the car does that.

 

[indyflick]

I can't wait for the day when the LEAF pack looks as odd to us as the Motorola DynaTAC cell phone batteries do today. That big battery allowed for about 60 minute talk time before a 10 hour recharge.

 

[LEAFfan]

Raise your feet about 3 inches and see where your legs end up.

Sure, the seat is "thick" and the carpet is "thin", but there is not
a lot of difference in elevation in there ... but more than I expected, ...
due to a "thicker" seat than I expected.

But, there is now insufficient headroom for me to sit there, ...
something like 2 inckes less headroom in the back than
in the front with the front seat all the way back.

One person mentioned that the front seat is Up/Down adjustable.
Not really, it is just on a fore/aft track that slopes up toward the front,
but no independent Up/Down adjustment like the 2010 Prius has.

Are you sure that is no 'up/down' dial? Did you see it in person? The specs say 6-way seat adj., and I've never seen a car without an up/down dial. Even my cheap Honda has a dial for height.

 

[garygid]

I sat in it (they said Production-Line made, about #24) in San Diego and asked (because I remembered the 6-way adjust), and was told that there was no U/D seat adjust.

When I fit with about 1" headroom, I did not look more closely. Maybe they did not know. However, it "appeared" to be a simple sloped rail.

 

[DeaneG]

There was definitely an up/down adjuster knob on the driver's seat, in addition to the fore/aft. I ran it all the way up and down on the prototype at Boardwalk Nissan. I specifically went there to try out the up/down adjustment (5'10" me, with 5'2" wife used to driving Lexuses with power memory seats).

The up/down adjustment ran the seat fore and aft over some portion of an inch as it went up and down, as if it was using a parallelogram linkage. The total up/down travel may have been roughly an inch. It was not difficult to turn the knob, as long as you were not sitting on the seat. Fore and aft travel was on a separate mechanism and moved the typical three or four inches.

 

[garygid]

Thanks, I will look for the U/D knob when I drive on 8 Oct.

 

[walterbays]

Amprius batteries - R&D suggests 40% more capacity

http://gigaom.com/cleantech/amprius-building-a-better-battery-from-the-anode-up/

http://www.technologyreview.com/energy/26294/?p1=A2

 

[mrxxmas]

The next-generation battery, like next-generation TV, may be 3-D, scientists reported here today at the 241st National Meeting and Exposition of the American Chemical Society (ACS). They described a new lithium-ion (Li-ion) battery, already available in a prototype version, with a three-dimensional interior architecture that could be perfect for the electric cars now appearing in auto dealer showrooms.


http://www.physorg.com/news/2011-03-fast-recharge-3d-lithium-ion-battery-prototype.html

 

[Synergetic]

The Answer to how the Nissan Leaf Battery is structured is on this page ...

http://www.eco-aesc-lb.com/en/product.html" onclick="window.open(this.href);return false;

High energy module (for BEV)
General specifications
Number of cells 4
Construction 2 parallel 2 series

High energy cell (for Battery Electric Vehicle)
Rated capacity (0.3C) 33.1 Ah Average voltage 3.8 V

So at 2P 2S Cells each module is 7.6 Volts @ 66.2 A/hr

48 Modules * 7.6 Volts = 364.8 Volts Pack Voltage * 66.2 A/hr = 24,149.76 W/Hr

Nominal Total Pack Capacity is 24kW/hr * 80 % = 19.3 kW/hr at 80 % charge

Case rests

 

[mwalsh]

A few pretty cool pics of a LEAF battery pack getting torn down on the Nissan LEAF FB page, posted by Norwegian owner Bent Mikkelstrup:

http://www.facebook.com/media/set/?set=o.141137487795&type=1" onclick="window.open(this.href);return false;