by tzs | 2025-08-18 22:42:31+00:00
> For the comparison to phone batteries, it's worth noting that until the last few years few if any phones allowed capping charge below 100% but now iPhones (15 and higher?), many or all Samsungs and unknown others allow capping for battery health.

Apple also added that the the M4 iPad Pro and M2 iPad Air. For those with an iPhone or iPad that does not support this there is a way to hack it. I got this from a comment here on HN many months ago, but don't remember who wrote it.

Apple Shortcuts automations can be trigged by battery level. Plug your charger into a smart outlet that can be controlled from Shortcuts, and simply make an automation that runs when the battery level goes above 80% that turns off the outlet.

If you want to even more closely match what Apple does on the devices with the 80% limit support built in also make a shortcut that turns on the outlet when the battery level goes below 75%.

Some smart plugs work better with Shortcuts than others. For example for an Amazon smart plug by understanding is that what you would have to do is make a routine to turn off the plug in the Alexa app. Then you would have to use a third party service like IFTTT to invoke the Alexa routine from a Shortcut.

A TP-Link Tapo plug is a little easier. You still have to set up the plug in the Tapo app, but the Tapo app includes Shortcuts integration so Shortcut actions to turn Tapo devices on and off automatically appear in Shortcuts.

That's still not perfect because you need to be logged into the Tapo app. I find that I occasionally get logged out (not sure if it just periodically logs you out or it happens on app updates) and then the Shortcut breaks until you log back in. I've found two ways to deal with that:

1. If it breaks the consequence is that night my iPad charges to 100%. You are supposed to do that occasionally anyway to keep the battery level indicator calibrated, and this is a convenient way to do that. If I wake up and the iPad is at 100%, I go log into the Tapo app.

2. I've got a Shortcut on my desktop to turn on the Tapo plug. I use that to turn it on before charging the iPad. If it doesn't turn on I know it is time to log in again. This way I only get the "fails to turn off" situation if I get logged out between the time I go to bed and the time the iPad passes 80%. I handle the need to occasionally charge to 100% by noticing when my iPhone 15 charges to 100% and then plugging the iPad into a non-smart outlet that night.

Best would be to get a plug that works with Shortcuts without needing to use the vendor's app and without needing an internet connection.

I thought that would be the Tapo because they can be set up as Matter devices, but after buying it I learned that this requires a Matter contoller and maybe a Thread border router. I have a couple of Amazon Echo devices that may be Matter controllers, but it turns out you need a controller for each platform (Alexa, Google, HomeKit) that you want to control the device from, so my Echos would not help with using a Matter device from Shortcuts.

My next step on the Matter path when I get some time is to look at Home Assistant. My understanding is that it can act as a Matter controller, and that the Home Assistant mobile app can has Shortcut integration on iOS. That should let me use the Tapo in Matter mode, and to replace the Tapo app and its annoying login requirement with the Home Assistant app.