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I've built a temperature sensor module that runs off of 4xAA batteries and sends data back to a computer via XBee. Works great, until the weather gets cold. At that point, the rechargeable AA batteries (I've tried duracell and eneloop) die very quickly. At 40 or so it seems like they can hardly muster the 3.3V needed to power the wireless.

This needs to be battery powered - running a wire to it isn't an option.

I'm trying plain old alkalines right now, but I was wondering if anyone had any tips on getting enough power out of batteries during the winter. Do I just need to double up and use 8 batteries? Do NiCad or LiPo cells work better than NiMH? Would switching to a different wireless module that can handle lower voltage solve the problem?

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Are the batteries actually dead or will they start to work if the temperature is increased? Is the XBee on all the time or does it spend most of its time sleeping?

Assuming the batteries just need to be warmed -- if the XBee does not have to be on all the time you may be able to perform a startup sequence that consists of drawing current from the batteries to warm them up and then enabling the XBee.

A wide input range DC-DC converter would also enable you to startup at lower voltages.

One other note the XBees can be run at 3V. They also draw very low currents in the hibernate modes when run at 3V. I have some plots of duty-cycle and current draw for different operating modes at http://wiblocks.luciani.org/white-papers/intro-to-zigbee.html

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  • \$\begingroup\$ I'm sleeping them when not used - the XBee gets woken up once a minute when I want to transmit a reading. I'll see what happens if I bring the batteries in and warm them up. \$\endgroup\$ – edebill Feb 24 '10 at 19:27
  • \$\begingroup\$ Another idea for batteries may be the Li-ion rechargeables from A123 Systems. I happened to be looking at the ANR26650 for a different project. The operating temperature range is -30degC to 60degC. These are 3.3V cells (26mm diameter, 65mm tall). The voltage is specified at apx 2.5V at 75% capacity at -20degC. \$\endgroup\$ – jluciani Feb 25 '10 at 1:13
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Lithium-Ion batteries might be your best option for rechargeables...They have a low self-discharge rate, and apparently work better in cold weather. Unfortunately, all of the popular types of batteries basically stop working at temperatures approaching freezing.

What you might consider doing is putting up a small solar cell for trickle charging, and insulating the batteries. If you can get the insulation right, the trickle charge will warm the batteries during the day, and the insulation will keep them warm at night.

Energizer claims that their Ultimate Lithium works well all the way down to -40ºC

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Use something like the Energizer Lithium AA's - they're rated to 40 below zero, and they're not too expensive if you look around. I use them in high altitude balloons where temperatures can get as low as -55 C, and they work a treat for me :)

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    \$\begingroup\$ We've extensively tested the Energize Lithiums in a cryochamber down to -40. You can still pull 2 amps out of them at -20. This drops to about 250 mA at -40, though. \$\endgroup\$ – Zuph May 17 '11 at 13:17
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Lithium thionyl chloride (Li/SOCL2) cells work well at low temperatures and are rated from -55 C. to +125 C.

Here's the datasheet for the Tadiran Extended Temperature TLH Series Batteries.

Here is an article on their application written by Tadiran.

The Cyclon sealed lead acid batteries may be a good choice if you need rechargeable batteries for low temperature. The company name seems to have changed, so I suggest looking up Cyclon at Digi-key.

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  • \$\begingroup\$ These are primary cells,and are not rechargeable. \$\endgroup\$ – Lior Bilia Oct 6 '14 at 16:06
  • \$\begingroup\$ I'll add that most Li/SOCL2's have a minimal ampacity (some as low as a few mA such as the Tadirans, others up to 100-200mA supposedly but unverified.) So yes, they work to very low temperatures, but can only supply small currents. These also seem to form an insulating layer upon sitting idle for a long time, which results in temporary voltage "sag" when used. \$\endgroup\$ – rdtsc Sep 10 '15 at 0:30
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Try LiFePO4 rechargeable batteries. You can get them in 18650 form-factor on eBay or Aliexpress, there are matching sockets with wires attached for sale, too.

Notice that these cells need lower charging current than typical LiIon - 3.6 — 3.65 volts instead of 4.2 — 4.23 volts.

Cyclists use these in winters for flashlights - even at -20C a fully charged cell can release about 50% of its nominal capacity before voltage drops below critical 2.7V

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