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Cooling an electric vehicle battery.

Started by Anthony William Sloman September 9, 2021
Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in  the battery.

The worst case would presumably be during fast charging.

One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end.

Nobody seems to do it, so it clearly isn't strictly necessary, but roughly halving the peak temperature inside the battery should make them last longer.

-- 
Bill Sloman, Sydney
torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev bill....@ieee.org:
> Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in the battery. > > The worst case would presumably be during fast charging. > > One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end. > > Nobody seems to do it, so it clearly isn't strictly necessary, but roughly halving the peak temperature inside the battery should make them last longer. >
Tesla batteries are liquid cooled (or heated when needed), there's a glykol filled flat tube that zig-zag between the cells
On 09/09/2021 18:28, Lasse Langwadt Christensen wrote:
> torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev bill....@ieee.org: >> Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in the battery. >> >> The worst case would presumably be during fast charging. >> >> One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end. >> >> Nobody seems to do it, so it clearly isn't strictly necessary, but roughly halving the peak temperature inside the battery should make them last longer. >> > > Tesla batteries are liquid cooled (or heated when needed), there's a glykol filled flat tube that zig-zag between the cells >
Here's a video of one that's been chopped apart: https://youtu.be/4JiDZVO9NdM?t=135 That's the Panasonic battery AFAIK. I don't know what shape the cells in the CATL LFP batteries (used in Shanghai manufactured model 3 sold in Australia at present).
On Thursday, September 9, 2021 at 1:29:02 AM UTC-7, lang...@fonz.dk wrote:
> torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev bill....@ieee.org: > > Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in the battery. > > > > The worst case would presumably be during fast charging. > > > > One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end. > > > > Nobody seems to do it, so it clearly isn't strictly necessary, but roughly halving the peak temperature inside the battery should make them last longer. > > > Tesla batteries are liquid cooled (or heated when needed), there's a glykol filled flat tube that zig-zag between the cells
Same for the Bolt, there are heat transfer plates between cells, with small pipes zz over the flat plate.
On 9/9/2021 4:08 AM, Anthony William Sloman wrote:
> Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in the battery. > > The worst case would presumably be during fast charging. > > One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end. > > Nobody seems to do it, so it clearly isn't strictly necessary, but roughly halving the peak temperature inside the battery should make them last longer. >
Tesla has a tube that runs thru the cells, the Chevy Bolt uses similar design to BMW where there's a coolant plate under the cells. I own a discontinued Chevy Volt plug-in hybrid which has a third design where the coolant runs in channels through plates in-between the cells which I think may be a little more efficient thermally than the previous two but it's not a compact solution and constrains the size and geometry of the pack more I believe, it's down the centerline of the vehicle amd tall which compromises the interior space a bit. It has three isolated coolant loops one for the engine, one for the power electronics, and one for the battery, and the engine loop is used to bring the battery loop and cabin air up to temp quickly on very cold days, as it's more efficient to burn a few drops of gas to do this than drain from the pack which is small by modern standards. All the loops use DexOS 50/50 as coolant, deionized water/ethylene glycol.
On 9/9/2021 9:42 AM, Ed Lee wrote:
> On Thursday, September 9, 2021 at 1:29:02 AM UTC-7, lang...@fonz.dk wrote: >> torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev bill....@ieee.org: >>> Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in the battery. >>> >>> The worst case would presumably be during fast charging. >>> >>> One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end. >>> >>> Nobody seems to do it, so it clearly isn't strictly necessary, but roughly halving the peak temperature inside the battery should make them last longer. >>> >> Tesla batteries are liquid cooled (or heated when needed), there's a glykol filled flat tube that zig-zag between the cells > > Same for the Bolt, there are heat transfer plates between cells, with small pipes zz over the flat plate. >
The Volt and Spark EV used that design, but I believe the Bolt is more similar to BMW there's a coolant plate under the cells, not in-between.
On 9/9/2021 9:48 AM, bitrex wrote:
> On 9/9/2021 9:42 AM, Ed Lee wrote: >> On Thursday, September 9, 2021 at 1:29:02 AM UTC-7, lang...@fonz.dk >> wrote: >>> torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev >>> bill....@ieee.org: >>>> Electric vehicle batteries are about 85% efficient, but the 15% of >>>> the energy that you put in that you don't get out has to appear as >>>> heat, generated in the battery. >>>> >>>> The worst case would presumably be during fast charging. >>>> >>>> One has to wonder whether anybody has built a battery with heat-pipe >>>> down the middle, sticking into heat-sink extrusions projecting from >>>> either end. >>>> >>>> Nobody seems to do it, so it clearly isn't strictly necessary, but >>>> roughly halving the peak temperature inside the battery should make >>>> them last longer. >>>> >>> Tesla batteries are liquid cooled (or heated when needed), there's a >>> glykol filled flat tube that zig-zag between the cells >> >> Same for the Bolt, there are heat transfer plates between cells, with >> small pipes zz over the flat plate. >> > > The Volt and Spark EV used that design, but I believe the Bolt is more > similar to BMW there's a coolant plate under the cells, not in-between.
The other advantage of cooled bottom-plate is that it can be load-bearing and pull double-duty as the battery tray and provide rigidity to the frame.
On 9/9/2021 4:28 AM, Lasse Langwadt Christensen wrote:
> torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev bill....@ieee.org: >> Electric vehicle batteries are about 85% efficient, but the 15% of the energy that you put in that you don't get out has to appear as heat, generated in the battery. >> >> The worst case would presumably be during fast charging. >> >> One has to wonder whether anybody has built a battery with heat-pipe down the middle, sticking into heat-sink extrusions projecting from either end. >> >> Nobody seems to do it, so it clearly isn't strictly necessary, but roughly halving the peak temperature inside the battery should make them last longer. >> > > Tesla batteries are liquid cooled (or heated when needed), there's a glykol filled flat tube that zig-zag between the cells >
The Tesla coolant loop design is probably the best from a cost/efficiency/reliability three-legged stool standpoint.
On Thursday, September 9, 2021 at 6:54:04 AM UTC-7, bitrex wrote:
> On 9/9/2021 9:48 AM, bitrex wrote: > > On 9/9/2021 9:42 AM, Ed Lee wrote: > >> On Thursday, September 9, 2021 at 1:29:02 AM UTC-7, lang...@fonz.dk > >> wrote: > >>> torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev > >>> bill....@ieee.org: > >>>> Electric vehicle batteries are about 85% efficient, but the 15% of > >>>> the energy that you put in that you don't get out has to appear as > >>>> heat, generated in the battery. > >>>> > >>>> The worst case would presumably be during fast charging. > >>>> > >>>> One has to wonder whether anybody has built a battery with heat-pipe > >>>> down the middle, sticking into heat-sink extrusions projecting from > >>>> either end. > >>>> > >>>> Nobody seems to do it, so it clearly isn't strictly necessary, but > >>>> roughly halving the peak temperature inside the battery should make > >>>> them last longer. > >>>> > >>> Tesla batteries are liquid cooled (or heated when needed), there's a > >>> glykol filled flat tube that zig-zag between the cells > >> > >> Same for the Bolt, there are heat transfer plates between cells, with > >> small pipes zz over the flat plate. > >> > > > > The Volt and Spark EV used that design, but I believe the Bolt is more > > similar to BMW there's a coolant plate under the cells, not in-between. > The other advantage of cooled bottom-plate is that it can be > load-bearing and pull double-duty as the battery tray and provide > rigidity to the frame.
OK, but heat travel up, more than down, at least for the air flow. I am considering removing the top plate of my Leaf battery to cool it. The bottom plate is heavy and rigid enough. However, it will no longer be an air-tight submarine, and my next dive would total the battery. I did drive the Leaf into a flooded ditch, up to the floor of the car.
On 9/9/2021 10:12 AM, Ed Lee wrote:
> On Thursday, September 9, 2021 at 6:54:04 AM UTC-7, bitrex wrote: >> On 9/9/2021 9:48 AM, bitrex wrote: >>> On 9/9/2021 9:42 AM, Ed Lee wrote: >>>> On Thursday, September 9, 2021 at 1:29:02 AM UTC-7, lang...@fonz.dk >>>> wrote: >>>>> torsdag den 9. september 2021 kl. 10.08.09 UTC+2 skrev >>>>> bill....@ieee.org: >>>>>> Electric vehicle batteries are about 85% efficient, but the 15% of >>>>>> the energy that you put in that you don't get out has to appear as >>>>>> heat, generated in the battery. >>>>>> >>>>>> The worst case would presumably be during fast charging. >>>>>> >>>>>> One has to wonder whether anybody has built a battery with heat-pipe >>>>>> down the middle, sticking into heat-sink extrusions projecting from >>>>>> either end. >>>>>> >>>>>> Nobody seems to do it, so it clearly isn't strictly necessary, but >>>>>> roughly halving the peak temperature inside the battery should make >>>>>> them last longer. >>>>>> >>>>> Tesla batteries are liquid cooled (or heated when needed), there's a >>>>> glykol filled flat tube that zig-zag between the cells >>>> >>>> Same for the Bolt, there are heat transfer plates between cells, with >>>> small pipes zz over the flat plate. >>>> >>> >>> The Volt and Spark EV used that design, but I believe the Bolt is more >>> similar to BMW there's a coolant plate under the cells, not in-between. >> The other advantage of cooled bottom-plate is that it can be >> load-bearing and pull double-duty as the battery tray and provide >> rigidity to the frame. > > OK, but heat travel up, more than down, at least for the air flow. I am considering removing the top plate of my Leaf battery to cool it. The bottom plate is heavy and rigid enough. However, it will no longer be an air-tight submarine, and my next dive would total the battery. > > I did drive the Leaf into a flooded ditch, up to the floor of the car. >
The "safing" method for the Mitsubishi iMieV's battery if the pack is say damaged in an accident or something is you disconnect, pull a few ports open, and pick the whole car up with a forklift and place it in three-foot deep pool of water for 24 hours. Not kidding, it's in the service manual lol