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What are your recommendations for methods or devices that are neither complex nor expensive to keep batteries warm and cool in a harsh (hot/cold/moist/dusty) environment, to ensure long cell life?

I'm designing a small solar-powered camera product and I have my choice of battery types: lithium, lead, nickel, etc. The camera would sleep most of the time so for average hourly use I estimate around 10mA x 12V (120mW). The environment could be very dusty, humid, hot, or cold. I cannot require constant maintenance, so a fan with filter does not seem to be a good idea. I can go with a larger pack to reduce the charge/discharge rate, if that is necessary.

Since this is for the outdoors and the initial sales would be in the United States, I expect ambient charging temperatures to be between -18°C/0°F in the winter and 38°C/100°F in the summer. Discharge temperatures could be as low as -34°C/-30°F in the winter and 38°C/100°F in the summer. Humidity can be as much as 100% but 87% is more typical in locations like Florida or Louisiana.

I was asked to supply the following info:

  • How your device looks: Imagine a security camera with a solar panel.
  • What it might cost: Less than USD $100 with parts cost less than $50 would be ideal. Any more than that and I might not consider creating the product.
  • What amount of field failure you can tolerate: Not sure how to quantify this. A life of 5 years would be fantastic. No less than 3 years.
  • Where it's going to be mounted by whom: Eaves, trees, walls, by non-trained personnel e.g. homeowners, farmers.
  • How heavy it might become: Small device, so about 1-2kg/2-4lb.

Is this even a concern? On my house I have these solar-powered security lights that have no heating or cooling. Just Ni-Cd batteries in a black plastic enclosure. I live in a climate with hot summers and cool winters. The devices are mounted in the sun and have been going strong for years. I see from reviews on those devices that they are installed in both very cold and very hot locations, and perform admirably. Yet the typically-recommended charge/discharge temperatures for Ni-Cd cells is 0°C to 45°C and -20°C to 65°C, respectively. Cells in an uninsulated black plastic box exposed to sun and snow surely must reach temperatures outside of that range, right?

And there are solar-powered trail cameras that hunters use in cold and hot weather.

Am I over-thinking this? Should I just drop some Ni-Cds in a black plastic enclosure and be done with it? Or are there some inexpensive temperature management solutions?

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  • \$\begingroup\$ can you define "hot", "cold", "humid"? \$\endgroup\$ – Marcus Müller Sep 3 '17 at 11:59
  • \$\begingroup\$ Snow, dust, mold, dead leaves on solar panels can be an issue. Also, if you want to keep the electronics cool in the summer, keep them away from direct sunlight. \$\endgroup\$ – peufeu Sep 3 '17 at 12:07
  • \$\begingroup\$ @MarcusMüller apologies, I thought that would be self-evident in the question since it is for an outdoors device. I have updated the question to reflect my expectations for temperature and humidity. \$\endgroup\$ – SlowBro Sep 3 '17 at 12:15
  • \$\begingroup\$ These expectations are realistic for moderate climates. For a camera in southern Sahara, or Antarctica, these wouldn't be sufficient :) But that's why I asked, thanks! \$\endgroup\$ – Marcus Müller Sep 3 '17 at 12:17
  • \$\begingroup\$ Minus 20 Celsius is a tad below what northern USA might expect. I had to design a battery powered piece of kit for Chicago and minus 30 was the spec. But this site isn't for developing a spec and seeking product recommendations is also off topic so, with a pun in mind, you are skating on thin ice. \$\endgroup\$ – Andy aka Sep 3 '17 at 14:46
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What are your recommendations to keep batteries warm and cool in a harsh (hot/cold/moist/dusty) environment, to ensure long cell life, that are neither complex nor expensive?

  1. Choose the device and technology that is appropriate for the environment by examination of the data sheet. Don't skimp on this! Talk to manufacturers and tell them what your expectations are.
  2. Look for similar applications and do some research as to what other people have had success with. Sounds like you have started this process
  3. Only choose devices that are made by manufacturers who have a reliable record for this technology
  4. Purchase the components from a reputable supplier/distributor that offers a decent support facility
  5. Apply the device by taking into account the recommendations in the data sheet and any other guidelines the suppliers/manufacturers provide.
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  • \$\begingroup\$ Apologies, I had more in mind what are your recommendations for actual devices or methods, such as liquid cooling or passive. I'll update my question. \$\endgroup\$ – SlowBro Sep 3 '17 at 12:16
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    \$\begingroup\$ @SlowBro for such recommendations, we'd need to have much more insight in how your device looks, what it might cost, what amount of field failure you can tolerate, where it's going to be mounted by whom, how heavy it might become, … So, this advice is far more valuable to you: because obviously, there's no "this works for all" solution, having a guideline how to find an appropriate solution is the best you'll get here. \$\endgroup\$ – Marcus Müller Sep 3 '17 at 12:19
  • \$\begingroup\$ Updated the question with your requested specs. \$\endgroup\$ – SlowBro Sep 3 '17 at 12:29

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