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Is there a difference with using two AA batteries versus a lithium coin cell battery versus lithium AA battery? I have found the lithium coin cell (CR2032 3v) is not lasting long. Would changing to two AA Batteries improve this and still be suitable in this kind of environment?

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  • \$\begingroup\$ You should look at the temperature performance, batteries slow down in cooler temps \$\endgroup\$
    – Voltage Spike
    Oct 18, 2023 at 5:32
  • \$\begingroup\$ Look at the low temperature specifications for the batteries you intend to use, different chemistries behave differently in low temperature performance. FWIW, the Elitech RC-5 temperature logger I have claims to work down to -30 C, and uses a generic CR2032. \$\endgroup\$
    – Neil_UK
    Oct 18, 2023 at 5:44
  • \$\begingroup\$ Start by calculating some rough power consumption. What do you need? Buck regulator, small MCU, MEMS temp sensor... what else? Indication? Real-time clock? A serial bus interface? Radio links? \$\endgroup\$
    – Lundin
    Oct 18, 2023 at 6:47
  • \$\begingroup\$ Is this a new or existing design of yours, or modifying someone else's? \$\endgroup\$
    – MiNiMe
    Oct 18, 2023 at 10:06

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Leaving aside the low temperature performance of batteries, a significant difference between alkaline AA's and CR2032's is the output voltage.

With a CR2032, you can reckon the voltage is about 3 V, until end of life, when it plummets.

With alkaline AA's, the voltage declines throughout the battery life, and there is still non-negligible capacity available even after you have dropped below 1 V per cell. Indeed, when I worked as a design engineer in the telecoms business, our battery portable equipment still had to function to specification at 0.75 V per cell.

If you use AA's, you might want to use a DC-DC converter to maximise battery life, or use 3 AA' and a linear regulator for simplicity.

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  • \$\begingroup\$ Thankyou for the help, can I ask how long it would take for the voltage to start declining if I am using 2 AA batteries? And does this also transfer to lithium AA batteries? \$\endgroup\$
    – Applebee
    Oct 18, 2023 at 7:34
  • \$\begingroup\$ @Lou better than asking Neil_UK for his interpretation of things, would be for you to find a datasheet for a AA battery and study the discharge curves. This will let YOU see and understand what they provide, and how that helps or influences your application and its solution. \$\endgroup\$ Oct 18, 2023 at 11:04
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    \$\begingroup\$ @DanielChisholm how long does it take for the voltage to start declining? Read what I wrote, 'the voltage declines throughout the battery life'. As soon as you start usingthe battery, the voltage starts declining. Lithium is a different chemistry, that's why I specifically said alkaline AA batteries. \$\endgroup\$
    – Neil_UK
    Oct 18, 2023 at 11:36

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