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[HOW TO] make Xiaomi sensors usb powered

Hi all,
for a few years now i’ve been struggling with the Xiaomi sensors battery replacement and for this wanted a solution so that i’d never have to replace the battery’s again. with a little help i found what i was looking for.

first off i drilled a hole in de side of the casing:


then i soldered the ground and the 3.3v output pin from a voltage reducer to the battery contacts:
Voltage reducer 4.5-24V to 3.3V : Link
then i hot glued the cable and connected the - to the - of the sensor:
then solder the + from the usb cable to the imput of the reducer:.
now connect the usb-cable to a wall-socket/power supply and press the connect button to see it work.
after this i used some UV-Resin to make sure the cables are not connecting when something moves(few drops) and UV glued the cable to the side of the case:

this way the battery lid can still be closed, the unit will never go into power-save, will never disconnect and reports to homey correctly.

image

let me know if you have any suggestions or better ideas :slight_smile:

kind regards
Ziglar

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Good solution!
Maybe a capacitor could be added to bridge short power fail?

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Should not be necessary if you use a standard USB cable. You can only connect it in one (the right) way.

How does the device know it’s not powered by a battery anymore?

Don’t think it does.

Cool idea. And nice to find a workarround.
Now you have to have access to a power source;) unscrewing the cap from a sensor one every 3 years is more trouble than all this?

Decent quality USB chargers will do that already :slight_smile:

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Great idea.
One could probably also use:

it doesnt :slight_smile: but since the voltage is always 3.3v and never drops the unit beleaves the battery is always 100%

if it was 3 years i wouldnt do this, in my case all of my Xiaomi sensors (11) lasts only 3weeks->3months.
plus this ‘mod’ is being done within half an hour.

Yes that would also work !, but since you’d still have to drill and solder i think my mod is more ‘clean’

Strange. Even the ones in the fridges and freezers last longer than that.
Or did you perform the 5 sec hack on those?

Motion sensors in the fridge, to check on the midnight snack? My only sensor which drains fast is the deep freeze

In my experience that doesn’t really matter, all my motion sensors have that hack and their batteries have lasted for more than a year now.

Maybe I am mistaken, but I see a temp sensor in @Ziglar’s post, not a motion sensor…

Didn’t know there was a5 second hack for the temp sensors too, my bad

And i thought it was also for temp/hum sensors, so my bad too :stuck_out_tongue:

I cannot find any info on Aqara hacks; other than for the motion sensor…
Can someone share a link perhaps?

Can’t imagine there is. Wouldn’t make Sense tbh. It reports in intervals and when there is a significant change.

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Agree, just curious what these hacks would be…