The most power for your pound

Wireless smart home technology is convenient, but there’s one downside: it’s battery powered. And however frugal IoT devices may be, the batteries will need recharging or replacing at some point. But which should you replace them with? Will the Duracell bunny really keep bouncing longer.. or is that just an amusing ad campaign to convince you spend more on the brand name batteries?

Luckily, science has the answer! The web site Battery Showdown has tested the longevity of dozens of common AA batteries, from expensive brand name batteries to cheap supermarket own-brands. Perfect for knowing which will keep your smart heating controls working longest.


The important thing to notice is that the useful life of each battery depends a lot on the “cutoff voltage” of the device you’re powering. That’s the point at which the battery is too flat for the device to work properly. For example, our wireless radiator valves need a minimum of 2.4v and take two batteries, so that’s 1.2v per battery. For other devices, find the datasheet online and check this figure.


Adjusting the cutoff slider to 1.2v on the results page shows that the Ikea Alkalisk (Alkaline) batteries deliver the biggest bang-for-your-buck at around £0.11/Ah. If you’d rather have the longest possible battery life, Energizer Ultimate Lithium delivers three times as much power per cell! On the other hand, it’s twelve times more expensive at about £1.20 each. Our customer David Hay managed to grab a bargain on eBay though, and has been very happy with them:

“I get about a year out of the normal batteries that came with my Heat Genius system, but I bought a load of AA Energiser lithium batteries from eBay for £1 each and they last even longer. So far they have been in for 6 months and are still reading 100%!”

Whichever battery you choose, make sure you recycle them when they’re dead. They contain some nasty chemicals, so definitely shouldn’t be thrown in your household bin! Some councils will collect them with your doorstep recycling – check your local recycling for information. Alternatively, you can drop them at most electronics retailers.Radiator valves batery

The most eco-friendly option would be rechargable batteries, but sadly they don’t usually output a high enough voltage to power Heat Genius smart radiator valves. Heat Genius customer Adam Burgess let us know that he’s been experimenting with some “high end” Kentli PH5 rechargeable batteries though, which incorporate a voltage regulator to make sure they always put out exactly 1.5v each. We’d love to hear your experiences too.

Which batteries work best for you? Found any bargains? Let us know.

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