Homey Community Forum

[HOW TO] make Xiaomi sensors usb powered

Tutorials
#1

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:

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then i soldered the ground and the 3.3v output pin from a voltage reducer to the battery contacts:
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Voltage reducer 4.5-24V to 3.3V : Link
then i hot glued the cable and connected the - to the - of the sensor:
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then solder the + from the usb cable to the imput of the reducer:
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.
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:
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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.

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

kind regards
Ziglar

13 Likes
#2

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

1 Like
#3

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

#4

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

#5

Don’t think it does.

#6

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?

#7

Decent quality USB chargers will do that already :slight_smile:

1 Like
#8

Great idea.
One could probably also use:

#9

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

#10

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.

#11

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

#12

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

#13

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

#14

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.

#15

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

#16

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

#17

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

#18

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

#19

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

1 Like
#20

Agree, just curious what these hacks would be…