If we are unable to get batteries to you, you will need to buy them locally.

The sensor unit uses AA lithium batteries. This is the kind of battery used in things like smoke alarms. They are the same size and shape as ordinary alkaline AA batteries, but should last a year. Energizer is the most common brand.If you need to buy them, they can be found on-line or from Argos at major branches of Sainsbury’s.

If you are a group supported by our Royal Academy of Engineering Ingenious programme funding, we are now shipping batteries within our monitors and if you need replacements, you can charge the cost on expenses.


NiMH rechargeable batteries will not supply a high enough voltage to the sensor. It is possible to use alkaline batteries, but we aren’t sure how long they will last and the relative humidity readings will become inaccurate when the voltage drops too far.


  • Do not attempt to recharge lithium batteries - these are not the same as the lithium-ion in your phone

  • Don’t leave the batteries in very hot places

  • Don’t run battery-operated devices under things where heat can build up

These are the same safety tips as for alkaline batteries, but these batteries store more energy, so it’s more important to remember them.

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