The answer here may be that a rechargeable battery is not the correct solution, and that a battery that is just used and replaced is more suitable but the intended application is:

  • An industrial environment where the battery may be subjected to hotter or colder temperatures (it is especially likely to be warmer when charging)

{EDIT} The temperature may get as high as 80 degrees C.. The more I read the harder this will be to find a battery for, rechargeable or not

  • Only likely to be charged in bursts of <1 minute (though this could be up to 12V ~1A)
  • Constantly draining at uW levels, with much less frequent instances of 100mW level draw for a couple of seconds
  • Aiming to power either 3V3 or 5V circuitry
  • Likely to be shipped internationally, which makes Lithium batteries more of a pain

Without wanting to give away too much information about the intended application, it will essentially be powering a piece of measurement equipment that records the amount of time a device is 'on'. This 'on' state is where the 12V comes from. This 'on' state would only last a minute or so usually (though you may get times where these minute periods happen quite frequently, maybe a 50% duty cycle for an hour). On top of that, the equipment could stay in storage for prolonged periods, with no charging at all. The instances of higher power draw are when measurements are read back from the device, but these may be even less frequent than operation, possibly at monthly intervals for example.

NiMH cells in an AA/AAA form factor (that can be easily replaced) were attractive, but some reading leads me to believe that they wont like being charged above room temperature.

Anyone have any suggestions for something that might be suitable? Many thanks in advance!

  • \$\begingroup\$ IIRC, the Nest thermostat does something similar as far as charging itself via the 12V solenoids that it controls. Of course it uses li-poly batteries. All other chemistries are kinda dead in consumer hardware \$\endgroup\$
    – Navin
    Sep 11, 2020 at 16:23
  • \$\begingroup\$ Yet another mission impossible, IMO. \$\endgroup\$ Sep 11, 2020 at 16:43
  • \$\begingroup\$ You don't say what the temperature range is. Some NiMH cells are specifically intended for industrial use and will operate over a wider temperature range than the consumer ones. \$\endgroup\$
    – Simon B
    Sep 11, 2020 at 23:51
  • \$\begingroup\$ how long between charges? \$\endgroup\$ Sep 12, 2020 at 4:44
  • \$\begingroup\$ @Jasen sometimes you may bet bursts quite frequently (with as little as seconds in between), sometimes it may be in storage for weeks/months \$\endgroup\$
    – Chuck990
    Sep 12, 2020 at 17:38

1 Answer 1

  • I know no Battery technology which likes cold. Maybe you need to protect / heat the battery

  • my first thought is some lead based battery (I knew they are used for emergency power in industrial scale). They keep charge for a longer time.

  • the short charge bursts might be a problem. One Solution might be collecting enough energy in supercaps and then transfer that into the "long term storage"

  • 3V3 or 5V... No. High voltage is your friend. At least for the battery. You will need a converter.

Appart from that, it sounds complex and special. Its hard to deliver a 100% solution for that

  • \$\begingroup\$ lead-acid batteries seem like a good solution, charging at 1A should not be a problem. \$\endgroup\$ Sep 12, 2020 at 4:44

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