Cooling

[solardave]

solardave, the numbers you're reporting and what you're hearing from the Volt is for when it's plugged in. Do you ever hear the TMS when it's just parked and not plugged in?

It's not using that much energy to keep the pack cool, maybe a kWh for the day. We've heard that the Volt will use the battery to cool itself if the SOC is above some level. Is the level configurable? Seems like that would be a nice feature.

Well the Volt taps the AC when it is running down the road to manage the battery and I don't drive around with the AC off in such high thermal conditions. In fact the Volt will engage the AC even if off if it needs TMS. So unless you let it do like a 3 hour soak in a lot the battery support for TMS is not needed, but is available. AFAIK the TMS is programed to run when the state of charge is greater than 50% in a hot soak environment. We look to plug in any time the Volt is parked if we can.

 

[GlennD]

Many good comments in this thread but the fact remains that the best you can do is the outside temperature. Water cooling will get the battery there faster but to cool lower you have to use some sort of refrigeration.

 

[WetEV]

Many good comments in this thread but the fact remains that the best you can do is the outside temperature. Water cooling will get the battery there faster but to cool lower you have to use some sort of refrigeration.

Actually, with evaporative cooling the best you can do is the dew point, which can be well below the air temperature.

Wild idea for hot areas or for long fast driving with many QC sessions. While moving, spray water into the air duct running below the batteries. Water evaporating removes a lot of heat. This area needs to be ok with being wet, as the air intakes are under the car and will get splashed in wet conditions. There is a good series of pictures in the forum showing how this duct is assembled. Thanks to Tony:

http://www.mynissanleaf.com/viewtopic.php?f=38&t=3896" onclick="window.open(this.href);return false;


What would be needed to do this modification would be spray nozzles in the air intakes, piping to a pump, adding a switch and perhaps some electronics and temperature sensors to control it...

Ideally the amount of water injected would be just enough to completely saturate the air leaving the duct. This would keep the duct almost dry and as cool as possible. By monitoring the outflow temperature and reducing water flow until that temperature goes up, as well as monitoring the CAN bus for vehicle speed and varying water flow with speed, perhaps this can be done. Or might just have a switch and leave the control up to the driver, with a pump and nozzle that provides about the correct amount of water at some reasonable speed, temperature and dew point combination.

I suspect that this would void the warranty. I am not a lawyer. I am not experienced in doing vehicle modifications. This is a speculation, not a proposal. This would not help the "park all day in a hot place" temperature problem.

From an engineering point of view, monitoring the inlet and outlet temperatures in the duct below the battery would provide some interesting data even without this modification. How much air goes through that duct?

 

[GlennD]

Evaperative cooling is the most primitive form of refrigeration. It may work fine in a dry climate like Phoenix but it is dead in the water on the east coast.

I suspect Nission does not want to build region specific Leafs.

In 2014 when my lease expires i think a second leaf is in my future. It fits my current needs perfectly. I do expect some battery degradation. With my 20 mile one way, I can deal with that.

 

[dusty2050]

For those who might be interested. I have started building a add on which in phase one will cool the battery while parked in the garage. It will not interfere with the cars warranty. The device consists of four liquid cooling pads which go between the current battery dust cover and the battery itself. There is a layer of foam insulation between the cool pads and the dust cover and the outside tempature. The cool pads (will not disclose at this time what they are made of) are held in place by the presure of the dust cover bolted back in place. None of the add on is permanentlly mounted to the car. The entire cool pad set can be removed as quickly as it takes to remove the dust cover and put it back. If the cool pads worst to leak, the liquid would flow down and just drip on the garage floor. There is no danger to the battery pack whatsoever. The cool packs are connected in series via two lines to a unit which chills the anifreeze mixture to a chilling 32 degress. The very large mass of the battery pack and the fact that there can't be any cool packs on the top of the battery case will mean that more than likely the system will not be able to cool the pack itself down to 32 degress. In fact the goal is to maintain the battery while connected at 72 degrees. While keeping power consumption as low as possible. One thing in the systems favor is the fact the battery modules are in the battery case very tightly and therefore actually form a single mass which can be cooled from the outside. (We already have a member that has successfully cooled his battery pack down to 72 degrees by using a window AC directing the cool air under the car while the outside tematures where well into the hundreds!) The unit does have a thermostat and if it is luckly enough to get it to the target tempature then it would shut off until needed again. If the system is found capable of bringing the tempature down to the 4 bar mark. Then the idea would be to bring it close to 4 bars and then due to its great mass it would sort of store some of the cold and would warm up slower, therefore shorting the time that the pack is at a higher tempature once disconnected and driven. This is of course if the system works as expected. Currenly the testing system is too large to be placed in the car for having an actual BMS. The plan is to eventually build a small system that can some how be added to the car in a way that does not distract from its function or interfere with the cars warranty. Of course to have the system be a true BMS system then some work would have to be done to have cooling on top of the battery which would cause some questions. But hey what do we have to loose. Even if Nissan is going to commit some research into a BMS when would we see it???

I am writting this to see if successful would any current leaf owners be interested in such a device. If so what would be a fair price for the add on. I myself do not plan on just sitting idle while my $40,000 investment turns into a paper weight!!!!

I am a software engineer by trade and I spent 20 years in the US Air Force with the last few years in an electrical engineer capacity. I believe I can build the deivce as long as I can come up with the needed funds.

Anyway I would love feedback comments and suggestions. Also I welcome questions on the idea. I will post photos of the system as it is being built but will hold some of the exact details confidential at the moment.

This of course is just thinking out loud and the information is provided as is where is and is not intended to suggest anything :>)

 

[SierraQ]

I have started building a add on which in phase one will cool the battery while parked in the garage. It will not interfere with the cars warranty. The device consists of four liquid cooling pads which go between the current battery dust cover and the battery itself. There is a layer of foam insulation between the cool pads and the dust cover and the outside tempature ...

...

I am writting this to see if successful would any current leaf owners be interested in such a device. If so what would be a fair price for the add on. I myself do not plan on just sitting idle while my $40,000 investment turns into a paper weight!!!!

I am a software engineer by trade and I spent 20 years in the US Air Force with the last few years in an electrical engineer capacity. I believe I can build the deivce as long as I can come up with the needed funds.

Anyway I would love feedback comments and suggestions. Also I welcome questions on the idea. I will post photos of the system as it is being built but will hold some of the exact details confidential at the moment.

This of course is just thinking out loud and the information is provided as is where is and is not intended to suggest anything :>)

This is an interesting idea but some experimentation is in order to see how effective it would be using battery temp data from the Leaf. Pressing insulated bags up against the battery may be counter productive if the system cannot transfer heat while on the go. It may actually retain heat. Would this fill up air channels designed to help remove heat while on the go? I've never looked in the underside so I'm not how the air-cooling works.

(We already have a member that has successfully cooled his battery pack down to 72 degrees by using a window AC directing the cool air under the car while the outside tematures where well into the hundreds!)

Do you have a reference for this? I assume it was in the garage and not while driving. I've tried something similar and it didn't appear to do anything. I am curious if the air was just blowing under the vehicle or directed into some external vents.

 

[Rauv]

Sounds interesting, but isnt there a consensus on this forum that near future versions of the Leaf will have active temperature management? I like the idea of battery cooling, though. Good luck.

 

[dusty2050]

Directed under and with some panels around the bottom to contain as much cool air as possible. Yes it is for storage only. He is a good friend of mine and is name here is EdmondLeaf. I am sure he would be glad to share ideas.

I have started building a add on which in phase one will cool the battery while parked in the garage. It will not interfere with the cars warranty. The device consists of four liquid cooling pads which go between the current battery dust cover and the battery itself. There is a layer of foam insulation between the cool pads and the dust cover and the outside tempature ...

...

I am writting this to see if successful would any current leaf owners be interested in such a device. If so what would be a fair price for the add on. I myself do not plan on just sitting idle while my $40,000 investment turns into a paper weight!!!!

I am a software engineer by trade and I spent 20 years in the US Air Force with the last few years in an electrical engineer capacity. I believe I can build the deivce as long as I can come up with the needed funds.

Anyway I would love feedback comments and suggestions. Also I welcome questions on the idea. I will post photos of the system as it is being built but will hold some of the exact details confidential at the moment.

This of course is just thinking out loud and the information is provided as is where is and is not intended to suggest anything :>)

This is an interesting idea but some experimentation is in order to see how effective it would be using battery temp data from the Leaf. Pressing insulated bags up against the battery may be counter productive if the system cannot transfer heat while on the go. It may actually retain heat. Would this fill up air channels designed to help remove heat while on the go? I've never looked in the underside so I'm not how the air-cooling works.

(We already have a member that has successfully cooled his battery pack down to 72 degrees by using a window AC directing the cool air under the car while the outside tematures where well into the hundreds!)

Do you have a reference for this? I assume it was in the garage and not while driving. I've tried something similar and it didn't appear to do anything. I am curious if the air was just blowing under the vehicle or directed into some external vents.

 

[dusty2050]

Sounds interesting, but isnt there a consensus on this forum that near future versions of the Leaf will have active temperature management? I like the idea of battery cooling, though. Good luck.

Yes but when is the million dollar question. I am not confident that it will be soon enough. I also live in a very hot area and we have been in the high triple digits for two weeks! Oklahoma City. Anyway I believe it will work. Tonight I was working on one of the heat exchangers. I hope to be testing tempatures by the weekend.

 

[TonyWilliams]

My thoughts are that you could mold a casting to the bottom of the metal battery carrier. It wouldn't have to be a metal, but obviously that would conduct heat better. The top of the pack has no battery module attachment points, and it's not even metal. I don't these that as worthwhile angle to an add-on cooling system.

On the bigger picture, though, why would anybody pay $$$$ for such a system, when you can go buy just about any other EV on the market with active TMS already included. Very few would proactively buy such a system, and even fewer would buy such a system AFTER they have to potentially pay big bucks to replace battery cells. I honestly see near zero market, which pushes the price per unit to insanity level.

I'd like to see a system that can heat the battery for winter, but that can be done with simple methods.

Nissan has never, to my knowledge, announced any upcoming TMS for LEAF. The closest comment that I can recall is by Mark Perry making reference to Dubai and other "really hot" areas, saying they might need a TMS, but of course, they don't market LEAF there, and gas is $1/gal. Nobody would buy one there, even with TMS.

 

[dusty2050]

My thoughts are that you could mold a casting to the bottom of the metal battery carrier. It wouldn't have to be a metal, but obviously that would conduct heat better. The top of the pack has no battery module attachment points, and it's not even metal. I don't these that as worthwhile angle to an add-on cooling system.

On the bigger picture, though, why would anybody pay $$$$ for such a system, when you can go buy just about any other EV on the market with active TMS already included. Very few would proactively buy such a system, and even fewer would buy such a system AFTER they have to potentially pay big bucks to replace battery cells. I honestly see near zero market, which pushes the price per unit to insanity level.

I'd like to see a system that can heat the battery for winter, but that can be done with simple methods.

Nissan has never, to my knowledge, announced any upcoming TMS for LEAF. The closest comment that I can recall is by Mark Perry making reference to Dubai and other "really hot" areas, saying they might need a TMS, but of course, they don't market LEAF there, and gas is $1/gal. Nobody would buy one there, even with TMS.

The system I am building can heat as well. The cool pads are made out of copper and aluminum for good thermal transfer also there is heat transfer compound between battery case and Col pad

 

[dusty2050]

First test complete. It is confirmed that the unit will have to be a closed system. The test system that was just attached to the bottom of the battery could not keep up with the surrounding heat as well as the battery heat. My next test will be with a fiberglass enclosure that wraps the battery and will have a self contained cooling heat exchanger. The unit will replace the current dust cover. The leaf battery will be in a cool box...

The chiller will have to be small enough to be placed somewhere under the car if it is to provide cooling while driving. Or if only extra cooling is desired while at home charging then it could be a seperate unit. The one I am building at the moment will only be used while at home in the garage (first prototype). I am convinced that allot of the degrading of the battery happens while charging. If you can keep the battery at a tempature of around 72 degrees while charging it will pack more in the battery with allot less stress.

 

[TonyWilliams]

I like the idea of replacing the "dust" cover with your cooler/heater. What's your idea for a chiller? What power? DC ?

 

[Stoaty]

I am convinced that allot of the degrading of the battery happens while charging. If you can keep the battery at a tempature of around 72 degrees while charging it will pack more in the battery with a lot less stress.

I haven't seen any data to support this hypothesis. It appears so far that the effects of ambient temperature overwhelm charging effects except perhaps in the coolest climates. What makes you think this is true?

 

[TonyWilliams]

I am convinced that allot of the degrading of the battery happens while charging. If you can keep the battery at a tempature of around 72 degrees while charging it will pack more in the battery with a lot less stress.

I haven't seen any data to support this hypothesis. It appears so far that the effects of ambient temperature overwhelm charging effects except perhaps in the coolest climates. What makes you think this is true?

I agree with you... The car sits + 90% of the time, exposed to the ambient temps.

 

[dusty2050]

I am convinced that allot of the degrading of the battery happens while charging. If you can keep the battery at a tempature of around 72 degrees while charging it will pack more in the battery with a lot less stress.

I haven't seen any data to support this hypothesis. It appears so far that the effects of ambient temperature overwhelm charging effects except perhaps in the coolest climates. What makes you think this is true?

When I am able to keep my garage in the 70's I seem to get a better charge and range that day. I mean at the moment a 100% on a great day is 264 gids (charging while the battery is cooler) but on a really hot garage temp 100% only gives 255 gids. I have had the opportunity to see this a half a dozen times. It would be great if someone else was able to do a simular test which has a gid meter.

 

[Stoaty]

When I am able to keep my garage in the 70's I seem to get a better charge and range that day. I mean at the moment a 100% on a great day is 264 gids (charging while the battery is cooler) but on a really hot garage temp 100% only gives 255 gids. I have had the opportunity to see this a half a dozen times. It would be great if someone else was able to do a simular test which has a gid meter.

This suggests a temporary reduction in battery capacity, not battery capacity degradation.

 

[DaveEV]

This suggests a temporary reduction in battery capacity, not battery capacity degradation.

Yep - what it really means is that the definition of a GID is changing if it goes up/down. As the battery warms up, it appears that a GID gets slightly bigger. Technically, a warm battery is able to hold/release more energy than a cold battery as internal resistance drops.

 

[KJD]

First test complete. It is confirmed that the unit will have to be a closed system. The test system that was just attached to the bottom of the battery could not keep up with the surrounding heat as well as the battery heat. My next test will be with a fiberglass enclosure that wraps the battery and will have a self contained cooling heat exchanger. The unit will replace the current dust cover. The leaf battery will be in a cool box...

The chiller will have to be small enough to be placed somewhere under the car if it is to provide cooling while driving. Or if only extra cooling is desired while at home charging then it could be a seperate unit. The one I am building at the moment will only be used while at home in the garage (first prototype). I am convinced that allot of the degrading of the battery happens while charging. If you can keep the battery at a tempature of around 72 degrees while charging it will pack more in the battery with allot less stress.

Nice work on the cooling system Dusty. I would really like to add this to my car.

Will the cooler have the options of running on 120v ? My employer has installed a couple of 120 outlets in the parking lot for employee use, but the J1772 cost was more than they wanted to do at this time.