Future LEAFs Needs Battery Thermal Mangement

[Nubo]

I was on a long trip recently with multiple quick charges, my battery temp was 9 bars, and it was only 65 degrees outside. Just for fun I felt under the car to see if any heat was radiating... and I found... plastic. You know it would be so simple just to thermally connect each battery module to a metal plate that is exposed to the air (or water that splashes) under the car. Just let the heat radiate off naturally. Nissan doesn't even do that.

Andy Palmer alluded to such things in the Tempe meeting. Any number of ways to get heat out of the pack; not all involve active cooling.

 

[Nubo]

Somewhere along the line, Nissan's battery testing failed. Whether that was due to flawed asumptions, inadequate methods, or "selective reporting" by engineers afflicted with "Go Fever", we'll probably never know.

I think its quite clear from that professor's video how Nissan's battery testing was flawed. Someone else just linked it, but I'll link it again for emphasis:
http://www.mynissanleaf.com/viewtopic.php?f=9&t=15796" onclick="window.open(this.href);return false;
Most manufacturer's battery testing does not accurately predict the capacity OVER TIME. By rapidly discharging and charging the battery, even at elevated temperatures, they are just trying to "beat the clock". That university's new testing procedures give me high hopes that the next generation of batteries will have both increased cycling ability and heat tolerance. Unfortunately, those testing methodologies weren't available when Nissan did their evaluation. I have no desire for the added complexity and energy consumption of a thermal management system, and after seeing that video I am convinced that it will not be necessary if they can get the right chemistry recipe.

Thanks for reminding me; I'd forgotten the implications of Dahn's techniques regarding Nissan's pre-production testing.

 

[mwalsh]

Well I for one, hope they don't. Read the Volt thread where one talks about the loss of EV range during some particularly hot weather. 25%? that is a LOT especially when you have no gas to rely on.

That was me. On the plus side, now we're back to "normal" in this part of the world the Volt is performing as we've expected all along. I've also been reminded that you can leave the Volt plugged in on really hot days, even when not charging, and the car will decide when to run thermal management off-the-grid. That's what we're going to try moving forward - I'd rather start out with a cooled battery than have the car trying to cool down an already hot battery while it's in use.

That said, I think my ultimate preference is for a robust battery chemistry/architecture that holds up well without active thermal management (in hot climes). That's what I would hold out hope for in the LEAF going forward, and obviously we're not there yet (at least not without knowing more about the "Lizard" pack).

The downside of actively cooling a limited range BEV:

http://gm-volt.com/forum/showthread.php?113538-Sudden-Catastrophic-Loss-of-Range" onclick="window.open(this.href);return false;

 

[DaveinOlyWA]

Exactly my point. ATesla has 10 kwh (and ten grand!) to blow on TMS. Well to be frank. I dont

 

[BrockWI]

Would it be that difficult or expensive to add a simple temp controlled fan that runs when the vehicle is on or plugged in? I know cooling could get more "fancy" using actual coolant and a radiator like what is done with the motor? But wouldn't a simple fan help a bunch with a sealed pack?

 

[Weatherman]

Exactly my point. ATesla has 10 kwh (and ten grand!) to blow on TMS. Well to be frank. I dont

It all depends on where you are.

When I was living in Seattle, I lived in a house without AC. With the exception of a couple of days a year, it was just fine. Spending a lot of money on an AC system would have been a waste. Living in Florida, I can go nearly an entire year without turning on heat. There are houses down here without centralized heating systems and they seem to do ok.

Could anyone imagine living in Minnesota without a heating system for their house, or living in Florida without AC? Sure it costs extra, but you pay money to buy what works best in your environment. Any current generation of BEV, without a TMS, doesn't work in warm climates.

 

[johnrhansen]

In warm climates, would it pay to build yourself an air conditioned garage to store the electric car in? Keep it at say 40 degrees... insulate it very well.... This way at least the car gets nice and cold soaked overnight when it's not in use, reducing the average temperature and increasing the life of the battery? Would the cost savings in not having to replace the car in 2 years pay for the cost of building and cooling the garage over that time?

 

[smkettner]

In warm climates, would it pay to build yourself an air conditioned garage to store the electric car in? Keep it at say 40 degrees... insulate it very well.... This way at least the car gets nice and cold soaked overnight when it's not in use, reducing the average temperature and increasing the life of the battery? Would the cost savings in not having to replace the car in 2 years pay for the cost of building and cooling the garage over that time?

Cost should be lower to just buy a Tesla.

 

[Weatherman]

In warm climates, would it pay to build yourself an air conditioned garage to store the electric car in? Keep it at say 40 degrees... insulate it very well.... This way at least the car gets nice and cold soaked overnight when it's not in use, reducing the average temperature and increasing the life of the battery? Would the cost savings in not having to replace the car in 2 years pay for the cost of building and cooling the garage over that time?

It's far more cost effective to just lease the car for a couple of years (if you really want to lease a LEAF, that is), or not bother with it at all.

My Volt does use extra energy to keep its battery cool, but the overhead is quite small at about 10% to 15% for about half the year. This represents only an extra 50 kWh per month to keep the battery cool. At 11.5c/kWH, that's an extra $6/month. Trivial cost, considering the benefit.

 

[myleaf]

Would it be that difficult or expensive to add a simple temp controlled fan that runs when the vehicle is on or plugged in? I know cooling could get more "fancy" using actual coolant and a radiator like what is done with the motor? But wouldn't a simple fan help a bunch with a sealed pack?

The electric A/C compressor seems very efficient and should be durable because it is a hermetically sealed unit similar to home A/C units.

I believe it was previously mentioned the possibility of venting cooled cabin air to the battery or possibly just use the A/C unit with a cool water loop?

Does anyone know what Tesla does?

 

[smkettner]

Exactly my point. ATesla has 10 kwh (and ten grand!) to blow on TMS. Well to be frank. I dont

Maybe it could be optional by region or part of a longer battery capacity warranty.
LEAF cooling should not cost as much as Tesla due to smaller battery and no supercharger heat.

 

[TonyWilliams]

Would it be that difficult or expensive to add a simple temp controlled fan that runs when the vehicle is on or plugged in? I know cooling could get more "fancy" using actual coolant and a radiator like what is done with the motor? But wouldn't a simple fan help a bunch with a sealed pack?

The electric A/C compressor seems very efficient and should be durable because it is a hermetically sealed unit similar to home A/C units.

I believe it was previously mentioned the possibility of venting cooled cabin air to the battery or possibly just use the A/C unit with a cool water loop?

Does anyone know what Tesla does?

Tesla uses liquid cooling to EVERY one of the thousands of 18650 cells. The liquid is cooled by the cabin air conditioner / heat pump. It is active, meaning the battery is cooled whether you are driving, charging, or parked.

Mitsubishi uses cabin cool air that is blown into the battery container. Crude, but maybe better than nothing.

 

[ydnas7]

Mitsubishi uses cabin cool air that is blown into the battery container. Crude, but maybe better than nothing.

only on the CHademo models, the cold country package only blew hot air (could be hill billy rigged to provide cold air though), the basic non Chademo model didn't even have any battery ventilation, was equivalent to the LEAF, its Manganese spinel batteries held up well.

It appears the Mitsubishi outlander PHEV battery seems sealed like the LEAF, and its a 12kWh unit with Chademo.

 

[JasonA]

It appears the Mitsubishi outlander PHEV battery seems sealed like the LEAF, and its a 12kWh unit with Chademo.

Why even have a 12kWh PHEV with DQCQ??

That's like a total...

It's either pure BEV with a CHAdeMO.. or not.. :roll:

 

[pkulak]

Because Japan is littered with quick chargers. And they probably aren't expensive to install. It's pretty much just a direct connection to the pack with a bunch of signaling. Why not have it? Why are we complaining about this?

 

[cwerdna]

Because Japan is littered with quick chargers. And they probably aren't expensive to install. It's pretty much just a direct connection to the pack with a bunch of signaling.

Yes, per http://www.chademo.com/" onclick="window.open(this.href);return false; there are 1967 in Japan.

As for the latter, nope. Take a look at http://www.americas.fujielectric.co... Comparison Study (25kW vs 50kW) 7-3-12.pdf.

And per http://www.mynissanleaf.com/viewtopic.php?p=332063&sid=337bbdf0241a8863446fcf48ab047029#p332063" onclick="window.open(this.href);return false;

Information provided by Nissan at Plugin 2013 indicates average cost for hardware and installation at dealers for the DC FC is $49K.

Best strategy for now on demand charges is to detune units to 20 or 25kW....

http://nissanqc.com/" onclick="window.open(this.href);return false; hardware alone is $15.5K. Nissan long ago bragged about getting the cost of the DC FC hardware down to $10K. It was there at http://web.archive.org/web/20120716030656/http://nissanqc.com/" onclick="window.open(this.href);return false;, but mysteriously vanished, leaving the $15.5K unit.

 

[pkulak]

As for the latter, nope.

I was talking about the QC port in the car.