The summer months are tough on air conditioners. Not only is your thermostat's set temperature likely lower because of the blistering heat, your outside AC unit has to use more energy to cool that warmer-than-average ambient air to that lower-than-average indoor temperature. As a result, you end up paying significantly more on your electric bill.

Mistbox wants to make the warmest months of the year a bit more bearable with version 2.0 of its energy-saving smart device. Mistbox 2.0 is designed to reduce the air temperature around your AC unit by gently spraying water whenever its built-in sensors and the weather forecast tell it to. 

Available for preorder now on Kickstarter, the second-gen Mistbox offers some key upgrades over its predecessor. It still connects to your outside AC unit, and you'll find similar sprinkler attachments that mist water from your garden hose, but the Mistbox 2.0 now operates via wind power rather than solar energy. 

Specifically, it comes with a small wind turbine attachment that relies on exhaust air from the unit's condenser fan for power. This is a smart update because you can depend on the fan's exhaust rather than worrying whether your Mistbox is getting enough sunlight. (Outside AC units consist of a compressor, a condenser and a secondary fan.)

The new Mistbox also uses cellular data instead of Wi-Fi. Partly because of this, Mistbox has changed its payment system to a subscription service. I'm not a fan of monthly subscription fees, but a cellular network makes sense in this case. I installed and began testing the original Mistbox unit at my house more than a year ago, only to run into a series of errors during the Wi-Fi configuration stage. I'm guessing my router just wasn't close enough to the spot where my outside AC unit is located. 

Mistbox says it's done more to treat the water that's sprayed around your AC unit with the second version of the gadget. Apparently, untreated water can damage your cooling system with harmful bacteria and other allergens. 

In addition to these major changes, Mistbox 2.0's design looks a lot better at a glance. That might not matter much, since it's going to be installed outside on your AC unit, but it could also translate to improved ease of use. We'll just have to see for ourselves.

Mistbox has raised over $180,000 so far on Kickstarter; its original funding goal was just $10,000. Units are expected to ship internationally in August starting at $89 for a prepaid year-long subscription (that converts to about £70 or AU$115) -- or for $399 to purchase it outright (plus a $49 subscription fee; $349 converts to £270 or AU$455). 

After the crowdfunding campaign ends, Mistbox devices will be available for purchase starting at $10 per month. Non-Kickstarter customers can also opt for a $99 prepaid annual subscription. A $39 activation fee will apply to all purchases as well, unless you preorder via Kickstarter.