ASIAir mini and USB Dew Heater

tomstein

I would like to start using a USB Dew Heater. There are no more free USB ports on my ASIAir but there is a free 12V port.
So I am thinking of getting a DC to USB A adapter and connecting both.
There are concerns about voltage incompatibilities though.
The dew heater specs are: input voltage of 5V, input current of 1.9-2.2A and power consumption of 9-10W.

I am not sure what happens when you have a 12V output port, an adapter changing from DC to USB (which is limited to 5V) and a device on the other end that pulls 5V. Is it as simple as the adapter just pulling 5V from the ASIAir's 12V? Or is there a risk I might fry any of my devices?

w7ay

tomstein input voltage of 5V

The ASIAIR output is not a DC level, but an unfiltered PWM voltage that switches rapidly between 0 and 12 volts. The duty cycle of the PWM is varied to give an average of 5V, but the device will see 12V about 40% of the time, and 0 volts 60% of the time.

https://en.wikipedia.org/wiki/Pulse-width_modulation

Check the specs of your dew heater if it can accept 12V.

It is a shame ZWO does not warn about it in the specs.

Chen

shawnhotz256

I would like to know aswell I plan to use two dew heaters but plan to use a usb to dc then use a dc splitter to connect both dew heaters to the asiair min dc port

Corsair

Also - the USB ports on the ASIAIR Mini/Plus aren't meant for USB power delivery.

Also remember that for the ASIAIR Mini - the power outlets are set to always be ON (there's no ability to adjust power like the ASIAIR Plus).

So, in conclusion, I would advise against using USB Dew Heaters with the ASIAIR Mini/Plus (even with DC to USB adapters).

Additional bits of info:
https://www.yuque.com/zwopkb/air_plus/aufptq

Although the 4 x 12V outputs are able to supply each up to 3A max per outlet, the unit as a hub is rated for max 6A total output.

https://eastwindastro.blogspot.com/2021/03/asiair-power-ports.html?m=1 Which states what @w7ay said above with more information.