Originally published at: AirGradient Open Air Max - First Thoughts
For the past two to three months, I’ve been testing the most exciting outdoor air quality monitor I’ve encountered yet – the AirGradient Open Air Max. This is essentially a significantly improved version of the more affordable Open Air monitor, featuring a range of additional features. As a result, the Max is both more accurate and vastly more flexible. While I discuss what exactly I mean soon, it’s fair to say that the improved flexibility is what interested me the most. To be fully transparent, I now work with AirGradient – you may have even spoken to me if you’ve…
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Thanks so much for this incredibly detailed breakdown.
It is great to hear real world insight from someone who has tested both the Open Air and the Open Air Max extensively. I appreciate your transparency regarding your role at AirGradient, it actually adds value knowing your perspective from both sides.
The improvements in flexibility especially with solar and cellular capabilities, really stood out to me. I am in a rural area where WiFi can be spotty so the ability to deploy a unit almost anywhere is a big plus. Also, the upgrade to the SHT40 sensor sounds like a big deal especially for anyone tracking ambient conditions closely.
That said, your conclusion really helped me weigh the pros and cons. Like you, I think I might lean toward the regular Open Air based on how I do use it but it is tempting knowing the max brings more future proof features.
Appreciate your honesty and the time you took to write this. Looking forward to hearing more user experiences in this thread.
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Thanks for your thoughts of the AirGradient Open Air Max.
I see some advantages: SIM-cellular data communication is the way to go. I expect that recovery of data via SD card is build in? If not one need it.
Hopefully there is a battery to cover failing solar energy. Is 10 watt solar panel really enough?
Is there a watchdog for keeping the battery healthy?
Personally I do not see a need for 2 PM sensors.
A note: Plantower sensors overestimate PM mass and particle counts in relation to e.g. Sensirion and Nova PM sensors. We see here an overestimation of the PMS5003 of about 150% to the Sensirion towards a reference NetOne BAM1020 PM sensor for PM2.5 and PM10.
I know some stations dry there airstream like the BAM1020 does, if needed so.
(If needed I have correlation data of a >3 years period of Nova, Sensirion and Plantower (every 15 minutes a record) towards a BAM 1020 (using hourly measurements.)
RH >60% (and in some way temp) creates an overestimation which is exponential. So be careful. One can adjust the overestimation but that is not easy.
In and output are close to each other with the PMS5003. So this creates some problems with the internal airstream in the station.
Personally I think that the MAX with cellular/solar/battery/2 PM sensors and RH/temp is a fair price.
My big questions are:
- Did you ever see any real use of the temp/RH figures?
- From measurements towards data analyse seems to be a big step for humans. This step is hardly done.
Hopefully my comments give some thoughts to improve this promising product.
Hi @teus,
All great questions!
Unfortunately, there is no slot for an SD card. I think that, at the moment, this is perhaps the biggest downside of the device. I would love to see this added in the future. The cellular is pretty stable, but nothing beats a backup.
The device utilises three 18650 batteries and can typically last around 5 days without needing a charge. The general rule is that a few hours of direct sunlight every day should keep it topped up enough for it to run consistently. It’s been optimised for battery life, so this means it only takes a reading every three minutes.
Yes, this is quite well documented and definitely something that needs to be considered. Fortunately, since the Plantower is so well studied (since other companies like PurpleAir also use it), there are a lot of resources around the sensor and corrections for it. With that said, I would definitely be interested in your data - how did you manage to collect it? If you would be willing to share, that would be fascinating, and you’re welcome to create a thread for it!
In my case, not really. As mentioned, I don’t really use my monitor for temperature or RH, but I can see this (much) more accurate sensor being beneficial for those who do. Since the Max uses the PMS5003 (non-T variant), this sensor is also used for the PM sensor humidity corrections.
I totally agree. I think most people just look at their monitors and take the measurements at face value. I don’t think many truly analyse the data or even consider if the monitor is accurate. Unfortunately, I think this is quite a common issue with most monitors and I think it’s one of the aspects that needs to be improved industry-wide.
Theorie of estimation the economics of solar-battery-cpu-sensor energy is helpful but the practice might be different:
- whatever we did on putting the ESP32 in deep sleep: sometimes the wakeup failed unexpectedly. A watchdog is needed.
- 5 days no sun is sometimes not enough: winter time: sun is hiding, panel might be in shadow, temperature is below zero, etc.: the quality of the battery is one key to solution, but:
- the battery should be kept in condition: not too low level, not too high level: advise: keep condition and watchdog separately from station and output voltage level battery as data.
Use 12V as energy source when no solar panel is attached. This allows a longer cable and use quality adapters!
Plantower or other sensor?
Plantower sensor is ok, I see here in Holland that one apply the Sensirion (SPS30 or even SPS5x) most of the times. The advantage of PMS or SPS is that they provide also particle counts as output. The future is: counting particles.
Advise: keep a sharp eye on RH figures: in the outside environment they fail after some weeks - months, or give a constant error. Newer types are often of a better quality.
The future: I foresee that stations (for outside applications) operate with a cloud of nearby sensors who communicate in a cloude to some gateway station. E.g. temp/RH sensors are very low energy consumers and can operate on battery which last for one year.
My opinion: Without proper analysing the PM sensor data does not make much sense.
Nova/Plantower/Sensirion/BAM1020 data:
The data is public avaialable. Send me an email and I send the measurements in CSV format.