I’ve been trying to find a nice temperature sensor I can put outside and have it be reliable for many years. I’m on my third replacement of cheap 433MHz temperature sensors from weather stations, and they start reading weird after a year or two.
I do like the low power aspect of 433MHz, two AA batteries last 2 years with these things. But the way they’re built is… a circuit board with a NTC thermistor, everything exposed to the elements.
Anyone have any experience with a nice 433MHz temperature I can use outdoors without worrying about it going bad? I like this IP66 one, for example, but haven’t tried it yet to see if it works with OMG or RTL_433: Ecowitt WN34L
I got the Ecowitt WN34L and it’s great. I purchased the “Oceania” version so it’s 433MHz. I’m using RTL_433 on a Raspberry Pi to publish to MQTT. Like $20
I also got the Ecowitt WH32_EP, which has an outdoor-rated, highly accurate sensor on it. It’s like $60, and I do the same thing with it. I had to put the transmitter part into a waterproof enclosure with a cable gland to protect it, but otherwise it’s great.
I’m checking out the OpenMQTTGateway project right now, which has an ESP-based RTL_433 implementation. I tried it in the past but it didn’t support the FSK protocol that these Ecowitt sensors use, but there seems to be movement on this front now. So I’ll try that so maybe I can get rid of the Pi + SDR thing and just have a small ESP with a CC1101 doing everything.
The current development version is the best to use with the Ecowitt, Froggit, Ambient Weather etc. weather stations, all rebranded Fineoffset stations, using FSK. The important thing here is to set the frequency to 868.35MHz if the station is a 868 version.
This works best with a compatible LilyGo (v2.1 1.6(.1)) or Heltec board, again depending in the 433 or 868MHz version, without any soldering required. With auto-discovery of OpenMQTTGateway, to get something like
Thanks @DigiH, I got it working with an ESP32 + CC1101 transceiver! No more Pi required. Using OMG + RTL_433_ESP module running on the ESP32, I’ve brought the complexity and cost of receiving my Ecowitt FSK sensors from $50 to $14.
The outdoor Ecowitt WH32_EP has been running for over a year now on the same two AA batteries. The WN34L is at 50% battery after the same period. Needless to say, very happy with my setup.
It’s hard to find a good CC1101 that works well for FSK. I have one that’s basically perfect (better than RTL_433), but the other ones I’ve bought since then are quite a bit worse.
I tried the LilyGo board, but it’s much worse than the CC1101 at FSK, even with the same antenna and distance.
So I have one installation that works really well, but can’t reproduce it very well for my other locations.
Apart from making sure that all your CC1101s and the LilyGo are also appropriate 433MHz version for your WN34L, I’m afraid it just comes down to different manufacturing quality
Hooking up external antennas to either might help in your case.
For me it is actually the other way round, with the LilyGos having better reception than the CC1101s.
I did buy some quality antennae from Mouser and tested about 10 of them. All the Mouser ones sucked, and the best antenna seems to be this one I got from Tindie (choose 433 MHz high gain antenna in the options).
Unfortunately, even the allegedly legit EBYTE CC1101 and high gain antenna sold on Tindie doesn’t match the quality of the random SOLO-branded CC1101 with the tiny spring antenna that I got on Amazon a couple years ago, which is the wonder-CC1101. It’s much smaller than the high gain antenna from Tindie but works much better. I bought new versions of the SOLO hoping they would match up, but they were quite a bit worse than the old one, despite looking almost identical.
The LilyGo performed remarkably worse than the CC1101 with every single antenna I tried.
@DigiH I wonder if it would be possible to attach two CC1101s to a single ESP32 running rtl_433_esp to fill in each other’s blanks, as it were.
@mtrista Have tried the same latest development version with all your ESPs and CC1101s, or could it also be that your really well working setup has an older, possibly better functioning version for your particular setup/devices?
I very much doubt it but honestly am not sure about any such possibility.
Best to ask the creator and maintainer of rtl_433_ESP, NorthernMan54, directly at the repo
I’ll do that, thanks! As for the version, I was literally just switching out the CC1101 and antennae from the same ESP32 with a single version of the project (well, OMG using the project as a dep)
The frequency doesn’t have anything to do with battery life. Some 2.4GHz device can have same power draw if the sleep-wakeup cycle is same. There are plenty of zigbee, ble etc sensors with good battery life. 433MHz is superior for range if tuned well.
It does actually. All other things being equal, the lower frequency will be more efficient per distance. You need more power to transmit 2.4GHz 200 feet compared to 433MHz. You’ll lose some bandwidth in exchange but not important when you’re just transmitting a couple numbers.
That being said, development is heavier on the 2.4GHz band these days, so they’re more likely to have more recent technology as far as battery saving goes. That makes up for the Zigbee sensors that can go years. But I’ve yet to see any of them match any old 433MHz sensors in transmit frequency. The Zigbee ones will transmit maybe every 5 minutes at best, sometimes even once an hour at best to save battery, while almost every 433MHz sensor will give you readings once a minute (or 2) and still last years with the same batteries.
If there’s an exception to this though, I’d love to switch over
That’s true, but also to transmit same quantity of data takes longer compared to higher frequency, so at the end net power used is the same.
In practice power efficiency depends on other factors, not frequency used.
Some dirty cheap BLE T/H sensors advertise every few seconds and have years of battery life with 2x AAA battery.
I newer researched anything for this use case, so I can’t suggest anything for the best and most rapid sensors. I only experimented with the ones I already had around, one Govee with display for indoors and one SwitchBot for outdoors.
but honestly am not sure about any such possibility.