Battery Cooling Experiment

See also:

This is an experiment that I fully expect will NOT work.

I've made some 3D printable parts to connect a hose from the passenger air vent (on a 24kWh ZE0 2011/2012 Nissan LEAF) to a nozzle that fits into the main battery disconnect panel hole (located between the front and back seats).

The inlet takes air from the passenger side air vet.

The cool air is directed towards the back of the battery case.

See for STL files to 3D print.

The theory is you can set the car to blow cold air out the air vents (AC: off, Mode: top vents only) then close all the other vents and have all that cold air blow over the top of the main battery - in the general vicinity of the cells that reside under the back seat.

Those are the cells that are most densely packed and therefore overheat the most when doing multiple fast charges.

Where the four temperature sensors are located. T1 is the one I'm most interested in.

I've used a Dyson Dc08 hose.

To install the blower nozzle you need to remove the battery disconnect cover plate. It's held down with 10mm head bolts.


Why this won't work:

  1. the cells are located inside a sealed metal can with an air gap between the top of the cells and the top of the can - blowing cold air over the top of the can will translate to very little cooling of the insides of those cells.
  2. my current exit nozzle design is a complete guess as to where I should be directing the airflow. (Ideally I'd have a thermal imaging camera looking in the area as it's being fast charged to find any hotspots - if they exist).
  3. opening the battery disconnect cover plate will freak some people out. Note: the battery disconnect plug is a fully waterproof and tamper resistant system. When it is removed the battery is disabled - so, no you can't electrocute yourself.
  4. The AC cooling function only works when the car is in Drive mode - so you can't run this when the car is fast charging - it can only be used before and afterwards.

Improvements that could be made:

  • Tape the edges of my air vent connector down with wide electrical tape to create a better seal around the vent outlet [Easy]
  • Tape over the other vents above the AV display [Easy]
  • Wrap the hose in insulation so the cold air is not heated up by the ambient air in the car. [Not too hard]
  • It would also be helpful to know where the cold air is dispersing. Is my nozzle pointing in the right direction? Ideally I'd point a small thermal camera down there to see what's going on. The current configuration is just a guess on my part. [Need to find a thermal imaging camera to borrow.]

Having said all that - this is a fairly simple, cheap and non-intrusive setup. If it did provide a bit of battery cooling then it might be worthwhile.

My next step is to test it out and use LeafSpy Pro to log the temperature readings of the battery.

I'll test a few strategies:

- just in my driveway to see if I can lower the temp of the back seat cells from ambient - during fast charging (on a long distance drive that requires multiple fast charges) - just before fast charging (on a long distance drive) - and just after fast charging (on a long distance drive) I'll update this page once I have any good data to support or undermine the utility of this experiment.

It would be helpful if someone else did the same so we could compare results. Good luck!

This project was inspired by: Nissan LEAF drive battery temperature measures by Terry Young from Cosmo Speed in Japan. His version is designed for the slightly different air vent shape in a 40KWh ZE1 LEAF.

Cheers, Paul

15 March 2021

Test 1 in my driveway

Disappointing (as expected).

Nissan Leaf battery cooling test 1 results. Temps are in degrees C.

Here's the results from the LeafSpy log showing the temperature at the 4 sensors in the battery, plus Ambient and Motor temp. These last two were included to provide something outside the battery to compare to. Unfortunately they much more dynamic than I was assuming. It looks like the motor heats up by 4 degrees C when the car is switched in to Drive mode!? And I really don't know what's going on with the Ambient temp reading.

As the the battery temp readings show - there a slight trend downwards but no enough to suggest I'm having much impact. I spent the first half an hour trying to get the AC cooling function to work with the car in not Drive mode. Then I switched to Drive mode and got the AC cooling the air down to 12 degrees C for the second half hour.

Page last modified on March 16, 2021, at 03:35 am
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