Trying to improve battery life for Smart TRV's

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I want to open up a discussion regarding battery power conservation when using smart TRV’s within home assistant. I think this will cover just about every make of TRV’s whether they be Wi-Fi, Zigbee, Z-Wave etc.

In my system (which happens to be HA with Node-Red and 17 x Moes Zigbee BRT-100 TRV’s) I control each TRV independently changing the temperature set point depending who is in the house and the time of day etc.

So, anyone who has TRV’s will know they eat batteries at a fairly high rate. Not surprising really; if you’ve ever tried to push the pin down on a TRV manually you’ll know how much force needs to activate the valve.

Assuming moving the valve (especially closing it fully) is the worst part of a TRV’s life as far as power consumption goes, I’ve taken taken to setting all TRV’s at 30°C (86°F) at 23:00 each evening. My theory being; this is way warmer than the UK can get to on any day of the year. Therefore the TRV’s stay fully open all night and are not trying to adjust themselves to achieve a temperature they will never reach, mainly because the heating is off overnight. So that’s point number one for discussion.

The second point is to establish if (in my case) a Zigbee read or write to a particular TRV uses any battery power.
It would be good if the answer to this is: No, providing nothing has changed. It would make sense that a device would cache it’s latest values and only go for a full read/write if it had. I just don’t know if this is true or not so some thoughts around this will be much appreciated.

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I believe the communication is the least of your worries.
I base this on that my temperature sensors and door sensors have a very long battery life even with smaller batteries.
I believe the motor is the issue here. But I’m not sure setting them to fully open is the best option.
When they just keep their position I think they are not using the motor. At least there is no sound from them so it would make sense that the motor isn’t running.
So you just add more movement and more battery drain with setting them to 30, I think.

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I disconnect my batteries from the TRV during the summer. I suspect setting your thermostat to 30c to prevent drain on the batteries will use alot more fuel heating the rooms. 15 devices with 2 AA in each. I buy the batteries in bulk. This week I got 40 Varta AA from screwfix for £16. It’ll be at least a year before I see how this works out.

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I believe you missed the part where he turns off the boiler over night.

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True story - I do turn the boiler off over night.

@Hellis81 - My experience is; when I’m in bed I can hear the TRV running their motors intermittently throughout the night as they try to keep the room at the set temperature (which of course they can’t as the boiler is off). My theory is; if a TRV uses most power when completely shutting a valve then I should open mine fully, which will stop all motor movement overnight and then return to the set temperature early in the morning which in most cases will not be a full valve closure thereby using less power overnight. I thin only time will tell !

@Spiro - I would disconnect the batteries but there a 17 of them and I have a short attention span :slight_smile: I do the same as you - AA’s in bulk - But even that annoys me as with 17 of them battery replacement seems to be a never ending task ! I’m half minded to try using a tiny 240VAC to 5VDC converter, bit of a pain to initially fit but zero batteries thereafter !

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underflooractuator
underflooractuator953×380 115 KB

I have 3 radiators that have covers and my TRVs don’t work so I fitted actuators to the radiators via miniR2 and an external temp sensor. It only opens valve when thermostat on same floor is on. It runs off mains.
Fitting external power sources to all your TRVs would be expensive.

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As Spiro just mentioned, you could replace them with thermal actuators.
That is what I did last winter.
I got so tired of all the battery issues, the noise and that our TRVs had a schedule that I could not disable.

Replaced them all with actuators and its like a dream. At least for me.
They are completely silent and run on mains.
I already had temperature sensors in the rooms so the investment wasn’t very high.
But actuator + temperature sensor + switch is about the same cost as a TRV.
However an actuator that can do partial open is more expensive.

I don’t think ours did that.
But then again I had external temperature sensor to ours.
I had a setpoint on the TRV that was higher than I wanted, and when I got to the real setpoint I turned off the radiator completely.

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So, for now I’m going to just set the TRV’s high over night then bring them back to their respective setting in the morning when the boiler kicks in and see how the batteries do.
I like the idea of the actuators you suggested but with 17 TRV’s under my belt it might be too costly to swap.
In the meantime I might well try converting one TRV to a mains supply, using a 230vac to 3.3vdc buck convertor. They are only about £1.60 on AliExpress. And , yes, I do have an electronics background so will be making sure it’s capable and safe before jumping in with both feet. My initial concern is the potential high current drawn by the motor when it’s on full tilt. Need to take some measurements with batteries fitted first !

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I am trying to do something similar, where I would like to connect 3x AA rechargeable batteries to the TRV. I had to lower the voltage of course, and I used a LD1117 chip to do so. But unfortunately it didn’t work and the TRV tells me “Hi” then 3.1V … while the LD1117 is outputting 2.86V. On the TRV noticed it says it doesn’t work with rechargeable battery, which indeed after one recharge it gives me the same error.

I am tired of changing the batteries every 6w to 2months. So if you found the magical solution to fit these TRV with external power (either 5V chargers, or bigger rechargeable batteries to last longer) … I am all hears :slight_smile:

Thanks

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Not TRVs but the same function

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Actually, what I had been using before seem to have been TRVs (I was just not aware of that word, so I called them something else). But I looked it up, that’s what I was using (or still am in some rooms; I will replace them over time).

I had used external power with them, plug-to-2AA-battery-adapters. They would work, but as I mentioned in an earlier post, they were not reliable. I read somewhere that actual batteries have slightly different electrical properties than these adapters (don’t quote me on that, I can’t remember exactly, all that I do remember is “they act like batteries, but not exactly as they should” without remembering the technical reasons).

These actuators Hellis81 recommended seem to work much better. I have been using them for a short time only as of this posting, but they do what they are supposed to. The run on 230V, so controlling them via smart outlet (via generic thermostat) works well, as long as your smart outlet and temperature sensors work fine.

For example, I had switched from an ESP32 DIY temperature sensor to an aqara bluetooth one, because that’s positioned in a better location and runs on battery, unlike the ESP32 one. However, it doesn’t report the temperature consistently, so when I’d restart Home Assistant for some reason, my generic thermostat would not work until these aqara bluetooth devices finally would decide to transmit the temperature. So I switched back to my ESP32 temperature sensor, which transmits every 30 seconds (or so).

So if you try these and something doesn’t work as expected, make sure it’s not because of something else (in this case, slow reports by bluetooth sensor) before giving up on it.

Oh, and I am using some old sonoff outlets I still had laying around, they are a bit louder. So you hear them throughout the night in the bed room when they toggle. But perhaps these miniR2s are not as loud.