@Mervyn1956 I also have problems with battery low errors. I pulled the batteries out of one of the heads, tested them with the multi-meter, still good, put brand new batteries in anyway and the battery low error came back on straight away. I do have another few heads, that started to show battery low within couple of weeks of installation with brand new batteries (I'm sure batteries in them are still fine). I'm using high quality, alkaline batteries.

Thanks for your reply.

I have purchased another 4 of these thermostats & will be setting them up later today.

If I get battery low warnings with these with new batteries in I will be contacting them & reporting them as faulty !!

  @Mervyn1956 I have just serviced another 4 low battery faults - again, the batteries I was replacing, were not too bad at all. The problem is, after replacing them all with brand new sets, many heads were not showing full battery straigth away, with most displaying only 2 out of 4 bars. One thermostat, initially was showing brand new battery as dead, but after several attempts, of turning the battery cover off-on, with the same batteries, it ended up showing 3 out of 4 bars. It almost looks like, some heads struggle to operate the motor during calibration, drawing too much current from the battery, what's causing them to send the false information about the battery's state of charge. I have checked the valve pins, thinking maybe they're seized (unlikely, as they almost brand new too), but no, they all operate freely. I have Danfoss RA valves, maybe Kasa heads are not powerfull enough to operate them efficiently?

  @Mervyn1956 

I have set up my other 4 thermostats & they all show full battery status initially.

I am going to keep an eye on them over the next week of so & see what happens.

  @Wayne-TP 

I have 5 KE100's.

Just set them up in the last few days.

I used the supplied batteries.

One of the thermostats showed low battery status after a couple of hours.

Two of the units show full battery status.

Two of the units show half battery

I replaced the batteries in the low battery status unit with new batteries &

it immediately shows half battery status.

  @Wayne-TP 

  @Wayne-TP 

The problem follows the device.

It is therefore the device NOT the batteries.

  @Wayne-TP 

I have also used supplied batteries first and then replaced them with Uniross Power Plus Ultra Alkaline. I agree with Mervyn1956 - it's nothing to do with batteries, it's the KE100 heads having problem