How to convert battery operating devices to hardwired

I need to convert all my battery operating devices to hardwired some use CR32 and some use the cr123 battery?

If those are all 3VDC batteries, then you can get 3VDC power supplies and solder the +ve and -ve terminals from the power supply to the appropriate terminals where the batteries would connect.

You’ll probably have to drill a hole in the case. Here’s an old example of one of my Hue motion sensors:

And you can use a 3.3Volt power supply that might be more availably than a 3V. I WOULD NOT try a 5V supply. A 5v supply will likely work for a while but will fail eventually.

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All the 3VDC supplies I purchased and use are all about 3.4-3.5 VDC.


You can distribute 12-24v from a bigish power supply and then convert that down to 3v via these types of converters:

I have a page in my notebook where I picked a 50amp 12v supply to mount in my attic and then using ZipCord (aka lamp cord) to distribute that out to the wall headers, where I'd mount something like I've shared. Then there would be the shortest length possible cable into the wall, popping out right behind whatever sensor needed it.

In other cases, if the sensor was USB already, I could use a slightly different 12v converter that has a USB and just use whatever included 3-6 ft USB cable that was provided.

I haven't built it yet, it's just sitting in a notebook waiting for me to get willing to climb around in an attic. Seems unlikely to ever make it to the top of my list :smiley:


I preferably not like to solder anything together I'm trying to replace the batteries in line Bosch motion detector to be hardwired and find a way that the kernel cannot unplug it and only use the batteries as back up. I'd also like to do the same with my door sensor in my other Samsung motion detector cuz they eat two batteries and I hate changing them I'd like to set it up and forget it.

So you’re not trying to replace the batteries with hardwired power, but rather add hardwired power and keep the batteries in place but only for backup power if there’s an outage?

That seems like it would be a lot more challenging to implement.


Yup - for sure!

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That would require a rechargable battery and a charging circuit. Just connecting 3 volts across a coin cell is asking for an explosion. If you must hardwire it, remove the battery.


Before you go too far, Consider those DC-DC stepdown boards are not FCC approved and while good for a hobby may create (leak) too much electrical noise for use "all over the house".


Or just run external batteries. This 2 D cell batteries on a smartthings button still at 100% after 2 years.


Wow I wasn't sure they even sold "D" batteries any more /s


The solution you want (hardwired + battery backup) doesn’t meet your requirements of no soldering.

So I’m closing this thread.

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