AC Infinity Controller 67 accuracy (or not)

Billy the Mountain

Well-Known Member

• Nov 30, 2021

• #1

I've had a controller 67 for a year or so. Its a nice upgrade from the standard controller and has worked like a charm thus far.
I recently noticed its readings and a Inkbird 608T differed by 8-9 % RH, A bag of cheap digital mini hydrometers were also reading far lower than the AC probe.

I figured the cheaper ones were wrong but decided to test against some other sensors I have.

Unconvinced, I wired up three different sensors to a raspberry pi, a BME280, an ATH20, and a SCD30. I let them run and logged data for a few days. All three are within a few % RH of one another. More importantly, all three are 8-9% lower than the AC probe.

There's a provision in the AC controller to enter an offset so its an easy fix.

I write this primarily because 8-9% is far enough off to be problematic; e.g. 70% night humidity is risky, 61% is fine.

 

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Last edited: Nov 30, 2021

smokey0418

Well-Known Member

• Nov 30, 2021

• #2

In the advanced setting the humidity calibration has a + - 8% offset for you.

enjoy.

 

Billy the Mountain

Well-Known Member

• Nov 30, 2021

• #3

I mentioned that

 

smokey0418

Well-Known Member

• Nov 30, 2021

• #4

When you toggle thorough the settings, it’s along the same area as the on and off . Adv, then toggle the other buttons to select what your after.

 

smokey0418

Well-Known Member

• Nov 30, 2021

• #5

oh I am sorry, thought you were asking. Will read better

 

Billy the Mountain

Well-Known Member

• Nov 30, 2021

• #6

No worries

Frankly I'm still surprised the "Swiss made sensor" in the AC probe is so far off.

 

smokey0418

Well-Known Member

• Nov 30, 2021

• #7

it looks like all the new fans also mimic the controller . Perhaps this is the weaker link rather than the probe.

 

Billy the Mountain

Well-Known Member

• Nov 30, 2021

• #8

Nah, the controller simply displays the output from the sensor.

 

smokey0418

Well-Known Member

• Nov 30, 2021

• #9

Your just under the belief that Swiss should be more accurate that’s all.

 

Billy the Mountain

Well-Known Member

• Nov 30, 2021

• #10

The AC documentation touted the "Swiss-made sensor'. Any hygrometer should be better than +9 % RH.

10/12 cheapo digital hygrometers were closer than the AC Infinity readings

 

LeastExpectedGrower

Well-Known Member

• Dec 1, 2021

• #11

I tested mine along with the inkbird, my Wifi, and a bunch of the little ones I put in jars then adjusted them all accordingly. The AC Infinity one was within about 1-2% for me. A ziploc bag, some salt and water, etc. and it took a day to sort. Probably worth doing. a few times a year just to make sure. I always figure this stuff is really 'ballpark' no matter what.

 

1

1212ham

Well-Known Member

• Dec 9, 2021

• #12

Billy the Mountain said:

The AC documentation touted the "Swiss-made sensor'. Any hygrometer should be better than +9 % RH.

10/12 cheapo digital hygrometers were closer than the AC Infinity readings

Click to expand...

Did you contact AC Infinity?

I sandwiched three sensors between two 62% Boveda packs in their little ziplock. The AC Infinity read 1% low, Inkbird was 3% high and the ecowitt wi-fi gateway was 4% high. I had previously entered a 7% correction in the Inkbird based on comparison to several other devices, now that correction is 3%.
The next test will be running them all together in the real world.

I tried the salt but it was too slow, things would stabilize in something like an hour with the Boveda packs.

 

Billy the Mountain

Well-Known Member

• Dec 9, 2021

• #13

No, the max -8% offset in the settings compensates. The readings now mirror the other sensors. I don't recall if I ever tried the salt slurry 75% RH test with the AC probe. I do it with the cheapo tiny ones and write the difference on a piece of tape.

 

LeastExpectedGrower

Well-Known Member

• Dec 10, 2021

• #14

Billy the Mountain said:

No, the max -8% offset in the settings compensates. The readings now mirror the other sensors. I don't recall if I ever tried the salt slurry 75% RH test with the AC probe. I do it with the cheapo tiny ones and write the difference on a piece of tape.

Click to expand...

One day when I was remote working here at home, I set up a couple salt calibration stations, did one that had my AC Infinity probe, my Inkbird and my wifi/bt temp/hygro then a second that had all my mini's. I actually have a bunch of boost packs so I certainly could try that method too.

Of course, with only one calibration point you're really only sure that you're accurate at 75% or at 62% and probably the further away you get from that, the more wonky things will be.