Air unit not working

Ok so we got 3 units from a German supplier. Airunit was connected as usual to the 12V rail of our drone.
After working for 2 minutes the airunit became unresponsive and now wont even power on. That happened to the second one also. The third one was connected to a stepdown converter at 7V and works so far. Our older air unit also works just fine on that drone without a stepdown. But the older air unit has an input voltage of 5-12v as the new ones we got state 7-12V. We never had a problem with the older ones ( I think we used 7 or 8 of them in the past)
So I am guessing there was a design change or something.
Now is there a way to make them work again? We tried holding the reset button for 10 sec but to no avail.

There are no change in the circuit. We change the input voltage label because we figured that powering air unit between 5-7V would sometimes cause problem.

The air unit protects itself up to 12.6V. Please make sure you did not exceed this.
Also, you may try if the computer recognize air unit when connecting to it. Power the air unit with 7-12V during the process.

Hi, this thread is related to the issue I’m having so I decided not to open a new one. Last year, I bought a HereLink unit for a large hexacopter prototype. It was rated for 5-12V so I designed a power distribution board with redundant 5.35V automotive rated buck converters to power most of the electronics, including the HereLink air unit. After testing the prototype, we started production and ordered HereLink units for the first batch of aircraft. To my surprise, new units came with a 7-12V label! I would like to know how is the power supply used inside the air unit? Does it have a LDO regulator? Does it use the raw voltage for some parts of the circuit? What would be some potential problems when powering it by 5.35V and why?

While the air unit will run on 5.35, there is a much higher chance of a brownout, due to resitance loss’s, current draw and we dont control the external devices you are connecting too. We always recommend 7-12v

Does that mean that there are not any radio performance compromises in this scenario? Assuming the input voltage is kept stable, of course. Power outputs to all external devices are current limited, we are using high-quality wires and flight logs have shown no more than 50mV of voltage fluctuation during test flights.

Radio performance will be the same yes. I can only say our recomendation is 7-12v, if you chose to run lower, we wont stop you, but make sure your power is solid.

We often see users share power rails, or with servos etc.

Great, thanks for clearing this up!

One of mine browned out on 5v, it was an older unit that still said 5-12v on the air unit, I tried a new unit and it kept shutting off on 7.5 and 8v as well, so I turned my BEC up to 12v and it’s been fine since.

I never had a single problem with the air unit running at 5.2-5.5V. Proper power supply design is crucial but people rarely take it seriously.

Proper power supply as in? I’ve got mine running on a Castle BEC, both of them that had issues (the one that browned out and died) and also the one that wouldn’t stay alive on anything less than 12v.

that i will agree with