MOWER: Active cooling to reduce battery operating temperature?

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Every time I run the 20" mower, I'm a little concerned when I open the battery cover, and it's just really warm in there.  I haven't used my IR thermometer to read actual temperatures, but I did watch a YouTube video where a guy was checking the temps before and after charging on the fast charger; and they were back to ambient temperature.

This is a 20" mower running on 2.0/2.5 AH batteries, not the 4.0/5.0/7.5, so maybe those batteries run cooler overall since they have more parallel strings of cells to draw from (either 2P or 3P, not 1P like I have).

So I'm sure some Ego Engineer has thought about putting the fan from the charger into the actual tools; maybe not all of them, but the high current draw like the blower and mower (probably chain saw too), might make sense?  The blower and chainsaw, maybe less so because the batteries are not enclosed like the mower.  Granted, the mower battery is the one that would be subject to the highest exposure to fine dust/dirt (unlike the trimmer, blower and chain saw).

I might run some back to back tests with the top cover removed to see if the temperature difference is significant.  Since there isn't a fan in the mower, the risk on pulling dust into the battery seems less than when it's recharging (which is why I place the charger on a nice clean work bench, not the ground).  And I'm not planning on mowing during a downpour... =)

Anyone else notice the battery compartment in the mower is significantly warmer than ambient?
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(a)Typical Engineer

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Posted 3 years ago

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Ken, Champion

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Keep in mind, Ego designed their batteries with heat management in mind. That's why the cells are arranged in an arc rather than a block, and they are well ventilated. And the individual cells are wrapped in a phase-change material that is activated electrically when the battery reaches a certain temperature to turn liquid and draw heat out of the cells.
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Blue Angel, Champion

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I guess I should have added that I basically stopped worrying about heat issues with Ego batteries after watching so many videos demonstrating their amazing design. :-)
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Jacob

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The pcm is melted at a certain temperature, that is how it is "activated".

It uses the "latent heat of fusion" in the pcm itself to act as a thermal battery.

More than anything, the pcm acts as a thermal regulator to maintain temperature at a specific temp for a long period of time. It isn't activated electrically. That would be the peltier effect.

Once the PCM has melted and temperature keeps rising, the pcm only provides thermal assistance based on the "Specific Heat" of the PCM.

Once the pcm has gone from liquid to solid, it does the above but backwards and equal.

Clear as mud?
(Edited)
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Blue Angel, Champion

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Barnaby created a lot of confusion when he incorrectly stated that the PCM was activated electronically.

The truth, as you point out, is just the simple physical properties of a phase change. Elegant in its simplicity. :-)
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Ken, Champion

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That'll teach me for taking the word of Ego's spokesman for how their products work! But it doesn't change the fact that Ego has designed their batteries with heat management in mind.
(Edited)
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Jacob

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There is a possibility that the pcm is electrically melted during cold operations. So if the pcm has a phase change temperature of 40deg F, whem the battery senses it has dropped below 40f it could heat the cells, which would heat the pcm to melt it. This would allow phase change to work over and over to keep the battery pack warm. The inverse is not possible without using the peltier effect as it would need to force the battery to cool itself.