johnlocke
Posts: 118
Joined: Fri Jan 08, 2016 3:47 pm
Delivery Date: 14 Dec 2015
Leaf Number: 300582

Re: Battery temp management for new leaf

Tue Sep 12, 2017 10:45 am

lorenfb wrote:
johnlocke wrote:
edatoakrun wrote:It would have been an odd decision, IMO to add either liquid cooling or pack insulation to the 2018 LEAF.

Even more bizarre, would be to add it to only some of (the likely lower production volume, higher capacity pack versions) the 2019 LEAFs.

Adding either feature is relatively trivial from an engineering standpoint, though very expensive in terms of production cost and efficiency.

If Nissan saw any benefit, why did it not add either or both features to the 2018 MY?

So, while anything is possible, until a high integrity source reports otherwise, I think we should expect Nissan to retain passive thermal management, primarily utilizing conductive cooling, in all 2019 MY LEAFs.

Either or both pack designs could use suppplementary active air cooling, much as some other BEV manufactures have, which is very low cost, but provides minimal benefits in terms of reducing battery temperature.

I'd regard blowing air from the standard AC system over the cell cases as mainly a placebo for those suffering from capacity loss anxiety, but it would allow Nissan to tout this benefit, to those misinformed buyers for which it could be appealing.

Air cooling via internal fans would be relatively cheap to do and have a minimal drain on the battery. Even a small airflow will remove a surprising amount of heat. MIght not help much while driving but could certainly help during charging. Could also cool down the battery while parked particularly overnight. It would have to be better than sitting in stagnant air trying to cool. I suppose that you could even vent into the rear passenger compartment for a little extra heat in the winter and dump it outside in the summer.


It depends how the battery is mounted/attached to the vehicle's chassis and the thermal resistance between
the battery and the chassis. If the thermal resistance is effectively zero, then the fans must also cool the
vehicle's chassis to cool the battery.

The battery is bolted onto the chassis. There aren't any thermal transfer pads and the battery is a sealed unit. The chassis is probably cooler than the battery anyway. The only reason that Nissan didn't implement cooling for the battery is cost. They are using the same battery casing and chassis to save money. Probably short-sighted on their part since it looks like the failure rate on the 16-17 30KWH batteries is going to be higher than the old 24KWH batteries. The 40KWH batteries are likely to have even more heat problems just because they will charged for longer periods and are capable of higher current draw(150 HP motor). There are rumors that the 60 KWH battery will require a TMS just for that reason.

My point was that regardless of the details, fan cooling would still be better than just leaving the battery sitting in still air and trying to cool itself by convection. If you could implement an air tunnel through the center with heatpipes to transfer heat from the battery stacks to the tunnel that would be even better.
Jamul, CA
San Diego East County

lorenfb
Posts: 1236
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Battery temp management for new leaf

Tue Sep 12, 2017 5:03 pm

johnlocke wrote:
lorenfb wrote:
johnlocke wrote:Air cooling via internal fans would be relatively cheap to do and have a minimal drain on the battery. Even a small airflow will remove a surprising amount of heat. MIght not help much while driving but could certainly help during charging. Could also cool down the battery while parked particularly overnight. It would have to be better than sitting in stagnant air trying to cool. I suppose that you could even vent into the rear passenger compartment for a little extra heat in the winter and dump it outside in the summer.


It depends how the battery is mounted/attached to the vehicle's chassis and the thermal resistance between
the battery and the chassis. If the thermal resistance is effectively zero, then the fans must also cool the
vehicle's chassis to cool the battery.

The battery is bolted onto the chassis. There aren't any thermal transfer pads and the battery is a sealed unit. The chassis is probably cooler than the battery anyway. The only reason that Nissan didn't implement cooling for the battery is cost. They are using the same battery casing and chassis to save money. Probably short-sighted on their part since it looks like the failure rate on the 16-17 30KWH batteries is going to be higher than the old 24KWH batteries. The 40KWH batteries are likely to have even more heat problems just because they will charged for longer periods and are capable of higher current draw(150 HP motor). There are rumors that the 60 KWH battery will require a TMS just for that reason.

My point was that regardless of the details, fan cooling would still be better than just leaving the battery sitting in still air and trying to cool itself by convection. If you could implement an air tunnel through the center with heatpipes to transfer heat from the battery stacks to the tunnel that would be even better.


"The battery is bolted onto the chassis. There aren't any thermal transfer pads and the battery is a sealed unit."

So the thermal resistance to the chassis is zero, right? Then using fans will have minimal effect cooling the battery,
since they will also attempt to cool the chassis (the chassis and the battery will always be at the same temp).

Please explain your rational.

SageBrush
Posts: 1067
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: Battery temp management for new leaf

Tue Sep 12, 2017 5:26 pm

lorenfb wrote:
johnlocke wrote:
lorenfb wrote:
It depends how the battery is mounted/attached to the vehicle's chassis and the thermal resistance between
the battery and the chassis. If the thermal resistance is effectively zero, then the fans must also cool the
vehicle's chassis to cool the battery.

The battery is bolted onto the chassis. There aren't any thermal transfer pads and the battery is a sealed unit. The chassis is probably cooler than the battery anyway. The only reason that Nissan didn't implement cooling for the battery is cost. They are using the same battery casing and chassis to save money. Probably short-sighted on their part since it looks like the failure rate on the 16-17 30KWH batteries is going to be higher than the old 24KWH batteries. The 40KWH batteries are likely to have even more heat problems just because they will charged for longer periods and are capable of higher current draw(150 HP motor). There are rumors that the 60 KWH battery will require a TMS just for that reason.

My point was that regardless of the details, fan cooling would still be better than just leaving the battery sitting in still air and trying to cool itself by convection. If you could implement an air tunnel through the center with heatpipes to transfer heat from the battery stacks to the tunnel that would be even better.


"The battery is bolted onto the chassis. There aren't any thermal transfer pads and the battery is a sealed unit."

So the thermal resistance to the chassis is zero, right? Then using fans will have minimal effect cooling the battery,
since they will also attempt to cool the chassis (the chassis and the battery will always be at the same temp).

Please explain your rational.

Tell that to Toyota and to Renault, since they both use active air cooling and both have MUCH better battery stories than Nissan.
True though, that I don't know if the air cooling is around the battery case or inside. I have always presumed the latter but I don't know that for sure.
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

WetEV
Posts: 1727
Joined: Fri May 04, 2012 8:25 am
Delivery Date: 16 Feb 2014
Location: Near Seattle, WA

Re: Battery temp management for new leaf

Tue Sep 12, 2017 9:08 pm

SageBrush wrote:Tell that to Toyota and to Renault, since they both use active air cooling and both have MUCH better battery stories than Nissan.


Which Toyota? The original RAV4EV had a NiMH battery, with no forced cooling, which had very good life. The second had a Tesla pack with liquid active cooling.

What Renault? Not sold in the USA.

The Ford Focus Electric has active liquid cooling, and does not seem to do better than the Leaf.

Battery life is a messy, complex subject. Amazing how many "experts" there are out there.
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
2012 Leaf SL Red (Totaled)
2014 Leaf SL Red

SageBrush
Posts: 1067
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: Battery temp management for new leaf

Wed Sep 13, 2017 2:14 am

WetEV wrote:
SageBrush wrote:Tell that to Toyota and to Renault, since they both use active air cooling and both have MUCH better battery stories than Nissan.


Which Toyota?

What Renault? Not sold in the USA..

Prius, Prius Prime
Zoe
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

powersurge
Posts: 677
Joined: Wed Oct 21, 2015 10:24 am
Delivery Date: 06 Dec 2014
Location: Long Island, NY

Re: Battery temp management for new leaf

Wed Sep 13, 2017 4:30 am

All this discussion or other cars' battery cooling is irrelevant to the Leaf.

The Leaf has what it has, and talking about the others is like saying that your neighbor has a nicer house than you.... So? Nissan is not going to give a hoot about what you think they should do... Buy or don't buy, That is our part that we can control....

WetEV
Posts: 1727
Joined: Fri May 04, 2012 8:25 am
Delivery Date: 16 Feb 2014
Location: Near Seattle, WA

Re: Battery temp management for new leaf

Wed Sep 13, 2017 5:14 am

SageBrush wrote:
WetEV wrote:
SageBrush wrote:Tell that to Toyota and to Renault, since they both use active air cooling and both have MUCH better battery stories than Nissan.


Which Toyota?

What Renault? Not sold in the USA..

Prius, Prius Prime
Zoe


Prius has NiMH battery, which is very heat tolerant. Is cooled by cabin air exhaust.

Battery chemistries are very different.

PP is new.
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
2012 Leaf SL Red (Totaled)
2014 Leaf SL Red

SageBrush
Posts: 1067
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: Colorado

Re: Battery temp management for new leaf

Wed Sep 13, 2017 6:08 am

WetEV wrote:
SageBrush wrote:
WetEV wrote:
Which Toyota?

What Renault? Not sold in the USA..

Prius, Prius Prime
Zoe


Prius has NiMH battery, which is very heat tolerant. Is cooled by cabin air exhaust.

Battery chemistries are very different.

PP is new.

Prius also had Li battery version
Zoe
I know Prime is new; my point is that Toyota thought it worthwhile to engineer active cooling. Toyota may be a bit slow jumping into the BEV arena but their engineering is top notch.
2013 Model 'S' with QC & rear-view camera
Bought off-lease Jan 2017 from N. California with 63.9 Ahr after 22k miles
Car is now enjoying an easy life in Colorado

GetOffYourGas
Posts: 1599
Joined: Tue Dec 20, 2011 6:56 pm
Delivery Date: 09 Mar 2012
Location: Syracuse, NY

Re: Battery temp management for new leaf

Wed Sep 13, 2017 6:36 am

lorenfb wrote:"The battery is bolted onto the chassis. There aren't any thermal transfer pads and the battery is a sealed unit."

So the thermal resistance to the chassis is zero, right? Then using fans will have minimal effect cooling the battery,
since they will also attempt to cool the chassis (the chassis and the battery will always be at the same temp).

Please explain your rational.


It sounds more like his claim is that the thermal resistance to the chassis is quite high. The sentences you quote claim that the battery is well insulated from the chassis, thermally speaking.
~Brian

EV Fleet:
2011 Torqeedo Travel 1003 electric outboard on a 22' sailboat
2012 Leaf SV
2015 C-Max Energi (302A package)

lorenfb
Posts: 1236
Joined: Tue Dec 17, 2013 10:53 pm
Delivery Date: 22 Nov 2013
Leaf Number: 416635
Location: SoCal

Re: Battery temp management for new leaf

Wed Sep 13, 2017 9:44 am

GetOffYourGas wrote:
lorenfb wrote:"The battery is bolted onto the chassis. There aren't any thermal transfer pads and the battery is a sealed unit."

So the thermal resistance to the chassis is zero, right? Then using fans will have minimal effect cooling the battery,
since they will also attempt to cool the chassis (the chassis and the battery will always be at the same temp).

Please explain your rational.


It sounds more like his claim is that the thermal resistance to the chassis is quite high. The sentences you quote claim that the battery is well insulated from the chassis, thermally speaking.


So no one really knows what the overall design parameters were/are for TMS being used in a Leaf.
Please, no more guessing!

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