Hey everybody! I have a use case for small scale nickel-metal hydride batteries where they need to be able to withstand high temperatures of 80+ degrees. I’m semi-familiar with battery cooling systems in EVs and have researched Adafruit.
Does anyone know of existing examples/the possibility of implementing battery cooling on a smaller scale? Open to any creative ideas too!
TIA
Hi Seb
Cooling from 80ºC+ is not exactly small scale. Especially if the 80º is the ambient temperature of the battery environment. You would have to get some cool air ducted from somewhere, or water. There are water cooled CPU heatsinks which might be adaptable somehow.
Cheers Bob
Hey @Seb280837, welcome to the forums!
As Bob said, cooling from 80ºC is no easy task! If you don’t mind me asking, what exactly is the use case for these? I find it quite interesting that you’ll have batteries that small in such a hot environment. Additionally, it may be helpful to know exactly what size you’re referring to, is it a single cell like an 18650, a small pack of cells with a BMS, etc.
Would love to help out more, so a bit more info could be really helpful, if you’re able to share of course.
Thanks Zach! The use case is inside a sauna, hence the high temps which will apply to all the electronics, so housing will play a part here too (moisture is the secondary consideration). In terms of size, somewhere within 3cm x 2 x 2 ideally. I’m a layman when it comes to electronics, so open to all suggestions about feasibility/solutions.
Hi Seb
Moisture ingress could be a problem here also.
It would be better if possible to keep the electronics and battery outside the sauna. Is there any reason to be inside. If you are connecting to some sort of sensors they could be inside and the smart bits out in the relative cool.
Cheers Bob
Hey @Seb280837,
Interesting! Feasibility wise, it’s probably going to be a tough challenge to have a moisture and heat insulated box full of electronics in the middle of a sauna. What exactly is this device meant to do? My intuition would be to place most of the items in a separate box outside the sauna, and interface with a sensor that’s placed inside.
@Robert93820 @Zach Thanks for these added insights. It’s actually in the form of bluetooth headphones that I’m exploring, which limits the possibility of placing elements outside the sauna
Hi Seb
The headphones themselves might object to 85º and what could be close to 100% humidity.
My yamaha phones only give a charging temperature range (no where near 85º) but nothing about operating conditions.
Cheers Bob
Thanks Robert. Yes, the headphones would need to handle the heat too. A lot of people use standard bluetooth headphones in the sauna, but they degrade relatively quickly. There are underwater headphones, so I’m confident the moisture part of the equation could be solved based on learnings from those. The heat is where the question still lies for all electronics involved
Hi Seb
Ahh the modern world.
The Sauna is a very old thing. Maybe we need to try very old techniques and just sit there and think which I believe is half of the equation.
Think! Think! That seems to be a dirty word these days. Oh well go with the times then.
That does not help your electronics though does it.
Cheers Bob
Hi Seb
Just to clarify. We ARE talking about 80ºC here. Depending on which part of the world you live in this could be 80ºF although that is only about 27ºC
Still 80ºC sounds hot enough to do skin damage when you consider bath room hot water has to be tempered down to below 50ºC to prevent accidental scalding. But, I have never been in a Sauna so only guessing and probably completely wrong.
Cheers Bob
I’m actually one who opts for silence and thinking time in the sauna, Robert. The solution I’m looking to achieve is for others (you’d be surprised how many people use off-the-shelf headphones in the there).
It is 80ºC, which is typically the temperature in saunas. It’s ambient, so not like having water of the same temp poured on you.
Still open to any solutions 
Hi Seb
I think you only have 2 alternatives.
Have the electronics inside the sauna at an ambient temperature of 80C and duct in cool air to create its own ambient environment or pipe in cold water to do the same. Both have mechanical problems with ducting etc and fan or pump to circulate said medium.
Have the electronics outside the actual sauna in a cool situation and if Bluetooth reception is a problem due to Sauna walls etc somehow have the Bluetooth antenna inside with all the electronics outside. Thus only a cable has to penetrate the Sauna enclosure.
I think option 2 would be far the easiest myself. But this is eventually up to you as you are the only one who knows of any mechanical limitations or obstacles to either solution.
Re Headphones. I think that once you deviate to something that is non “standard” the cost will rise in what seems to be an exponential manner. Depends on what sort of budget is involved.
The alternative here is to provide the Bluetooth signal and leave the headphone problem and expense up to the user.
Cheers Bob
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