I HATE Batteries! - Converting Wireless to Wired (a cheapskate’s guide)

[James]

I seem to be alone in my belief that batteries suck. Why are we adding more of these inconvenient, polluting monsters to our homes when good old fashioned wall power is there for us? In this video I’ll be exploring how to convert a battery powered smart home sensor to wall power for a total price of about 5 bucks.

 

 

 

[darknessblade]

Why did Linus not use some old Prototype PCB board?

 

 

[manikyath]

11 minutes ago, darknessblade said:

Why did Linus not use some old Prototype PCB board?

because for something as simple as this, you may as well just not.

 

on topic:

i love using the diode trick myself to slice just a volt or so down, the issue with the spikes could probably be resolved with a capacitor, that way a peak doesnt immediately pull the dropped voltage down even more.

 

my setup would probably be 3(.3)v linear regulator (because then i have a wide choice of input voltages), some crappy diodes (cheaper really IS better for this usage) to drop it down further if needed, and then a cap to smooth it out, potentially with a nice high value resistor to have at least half a mA of load or something along that range.

 

alternatively, there do exist 'adjustable' linear regulators that you can adjust with a potentiometer.

 

---

alternative.. a trick i've used a few times in the past for very low power draw devices, is to replace the battery with a similarly sized supercap, and build a loop of enameled copper wire into the device somewhere, that way the device stays 'wireless', but it can just live on or near a qi charger. ideally you do add something like a 2.7v zener diode to make sure it doesnt over-charge. usually it's so low power that it can charge just off the standby sensing of a Qi charger, without activating it. this is a whole lot more involved than just sticking a voltage regulator and some passives in the back, though.

[Applefreak]

57 minutes ago, James said:

I seem to be alone in my belief that batteries suck. Why are we adding more of these inconvenient, polluting monsters to our homes when good old fashioned wall power is there for us? In this video I’ll be exploring how to convert a battery powered smart home sensor to wall power for a total price of about 5 bucks.

 

 

 

I totally get the point of this video, even without smart controls in my house. As far as e-waste goes, I've upgraded smoke detectors from round cells to regular AA batteries. Theoretically those should last 10+ years now. You guys have 3d printers, get yourself a base for those tiny sensors, more room to work with. Btw. older 1 Amp micro b charges often times are not that hard to open up. You can directly modify the pcb inside, way cleaner looking.

[qqii]

This is a pretty neat idea!

 

That said having the equipment and knowledge to figure out the right components (plus the further issues as seen in the video) makes this a non starter for all but the most badly designed devices. Battery powered smart devices often last long enough for their flexibility and size to be worth it.

 

An alternative for Linus could have been to use any other home assistant compatible wired thermostat and configure the heating via HA. This allows greater flexibility as you could combine multiple sensors and other inputs in determining your heating schedule.

[ImorallySourcedElectrons]

40 minutes ago, manikyath said:

because for something as simple as this, you may as well just not.

 

on topic:

i love using the diode trick myself to slice just a volt or so down, the issue with the spikes could probably be resolved with a capacitor, that way a peak doesnt immediately pull the dropped voltage down even more.

 

my setup would probably be 3(.3)v linear regulator (because then i have a wide choice of input voltages), some crappy diodes (cheaper really IS better for this usage) to drop it down further if needed, and then a cap to smooth it out, potentially with a nice high value resistor to have at least half a mA of load or something along that range.

 

alternatively, there do exist 'adjustable' linear regulators that you can adjust with a potentiometer.

 

---

alternative.. a trick i've used a few times in the past for very low power draw devices, is to replace the battery with a similarly sized supercap, and build a loop of enameled copper wire into the device somewhere, that way the device stays 'wireless', but it can just live on or near a qi charger. ideally you do add something like a 2.7v zener diode to make sure it doesnt over-charge. usually it's so low power that it can charge just off the standby sensing of a Qi charger, without activating it. this is a whole lot more involved than just sticking a voltage regulator and some passives in the back, though.

Could use a TL431 with a few resistors to do it on the cheap, but you could also play a few tricks using the reference terminals. Way too many ways to go! It'd actually be quite doable at this point to make small replacement PCBs that you'd solder wires to given the more recent ultra small packages.

[manikyath]

1 minute ago, ImorallySourcedElectrons said:

Could use a TL431 with a few resistors to do it on the cheap, but you could also play a few tricks using the reference terminals. Way too many ways to go! It'd actually be quite doable at this point to make small replacement PCBs that you'd solder wires to given the more recent ultra small packages.

product idea: design and manufacture replacement power devices that fit in CR2032 (and other popular button cell) slots that allow you to power the device from some form of power supply.

 

given that button cell stuff is in the µA range generally, they could even have a supercap and a magnetic wireless charging thing.

 

i'd be so down for having something like that for my digital calipers, i need to replace the battery every few years, but 99% of the time it's sitting on it's exact spot on my tool wall, it could be topping up charge constantly and have a 2hr battery life or something.

 

now, someone, go make this.

[Nystemy]

To be fair. This is a bit hacky. But it could be worse.

However. For battery operated devices like these, they tend to not care about "exactly" when it comes to voltages. Especially as the battery gets used over time, then it will drop in voltage and the device will still work until it drops low enough. And that is usually a good bit lower.

 

So don't aim for 3.2 volts. Anywhere from 2.5-3.5 volts is practically guaranteed to work for any device relying on a single lithium cell. _{(For an example a CR2032)}
 

And as Linus already stated, SMD components are a pain to solder without aid. _{(I usually just stick them down on a strip of polyamid tape. SOT-23-6 packages are too tiny for helping hands to be practical.)}
But a 3.3 volt regulator would be fine. A device like this won't consume any major amounts of current, so heat buildup isn't a worry. Even considering that it is a thermometer. I would have gone with an _(overkill) TO-220 package for ease of soldering.

EDIT:
The 4 diods in series is also a half assed solution....
Just use a Zener diode instead, a 1.8 volt one is a standard value. _{(It lets current flow over it in reverse with a more or less constant 1.8 volt drop.)}
And then have a capacitor in parallel with the device/load, I would go with 22µF, it should be good enough to handle the peak currents for these short bursts of activity.

[ToboRobot]

8 minutes ago, manikyath said:

product idea: design and manufacture replacement power devices that fit in CR2032 (and other popular button cell) slots that allow you to power the device from some form of power supply.

 

given that button cell stuff is in the µA range generally, they could even have a supercap and a magnetic wireless charging thing.

 

i'd be so down for having something like that for my digital calipers, i need to replace the battery every few years, but 99% of the time it's sitting on it's exact spot on my tool wall, it could be topping up charge constantly and have a 2hr battery life or something.

 

now, someone, go make this.

USB or PoE to Universal Battery Converter.

[manikyath]

Just now, ToboRobot said:

USB or PoE to Universal Battery Converter.

i wouldnt go USB, and certainly not PoE. the 'button cell replacer' side should be able to be entirely enclosed within the device (because a button cell would be), so wireless power seems the best solution there. perhaps the outside wireless power half could have a USB version, but i feel like the way to go is just absolute bare basics wall power supply, because it's microwatts, any sort of propper DC power supply will use more power in switching than the device ends up pulling.

[ImorallySourcedElectrons]

33 minutes ago, manikyath said:

product idea: design and manufacture replacement power devices that fit in CR2032 (and other popular button cell) slots that allow you to power the device from some form of power supply.

 

given that button cell stuff is in the µA range generally, they could even have a supercap and a magnetic wireless charging thing.

 

i'd be so down for having something like that for my digital calipers, i need to replace the battery every few years, but 99% of the time it's sitting on it's exact spot on my tool wall, it could be topping up charge constantly and have a 2hr battery life or something.

 

now, someone, go make this.

Currently working on a move abroad so a bit busy, but if you poke me again in a couple of months I could probably help design something FoSS to do the job.

[manikyath]

1 minute ago, ImorallySourcedElectrons said:

Currently working on a move abroad so a bit busy, but if you poke me again in a couple of months I could probably help design something FoSS to do the job.

actually.. LTT merch idea?

[ToboRobot]

56 minutes ago, manikyath said:

i wouldnt go USB, and certainly not PoE. the 'button cell replacer' side should be able to be entirely enclosed within the device (because a button cell would be), so wireless power seems the best solution there. perhaps the outside wireless power half could have a USB version, but i feel like the way to go is just absolute bare basics wall power supply, because it's microwatts, any sort of propper DC power supply will use more power in switching than the device ends up pulling.

For it to be universal, you would have different sized adapters (Plastic sized and shaped like the battery with a universal interconnect to the power source).

So a dumb thing that acts like a battery and connects via wire to whatever USB/PoE/DC adapter source of power with a module to regulate the power to the battery specs.

[Ein0r]

For the money I'd need to safely diy this, I could probably buy batteries for these devices for life.

[nineclicks]

I'd love to do this with a bunch of my Zigbee light buttons they they are meant to just stick to the wall so that would be a cable, or several in each room routed down or along a wall.

 

I did, however, do this with my wife's LED christmas village. The idea of flipping a bunch of switches every morning then back off every night was just not something I could tolerate, even if I wasn't the one doing it so I made a little JST connect hub for them all to connect to and hooked that up to a micro USB charger. Luckily they were all 4.5v so I didn't bother with any conversion.

[nineclicks]

7 minutes ago, Ein0r said:

For the money I'd need to safely diy this, I could probably buy batteries for these devices for life.

I would agree with you if this were playing with mains power, but we are talking about the low voltage side of a UL/ETL device.

[manikyath]

18 minutes ago, ToboRobot said:

For it to be universal, you would have different sized adapters (Plastic sized and shaped like the battery with a universal interconnect to the power source).

So a dumb thing that acts like a battery and connects via wire to whatever USB/PoE/DC adapter source of power with a module to regulate the power to the battery specs.

put all the voltage logic in a battery-shaped and sized device, and have that interface with an outside source somehow. if batterizer can shove a joule thief in a tiny wedge on a AA battery, i bet it's possible to stick a voltage regulator in a LR1130 size too.

 

you basicly only need to design a CR2032 sized  module (bigger 3V button cells can use a shim), and an LR1130 sized module with a shim for LR44. that's literally  all of it.

on that note... add AA's and AAA's to that list for TV remotes while we're at it.

 

and the weird stuff that uses those tiny 12V batteries.. that's literally 4 LR44's stacked, so as long as they can interface in stacked form it'll work.

 

10 minutes ago, Caroline said:

If you don't want to deal with batteries or spend hours fixing design flaws don't buy useless smart devices then

i mean.. if only it was only a 'smart devices' problem...

- digital measurement equipment

- remotes

- clocks

- thermometers/hygrometers

- decorative lighting

- those stupid AAAA's in touch screen pens (protip if anyone annoyed with the availability of these is scrolling past: duracell 9V batteries contain 6 cells that are close enough to work.)

- ...

2 minutes ago, nineclicks said:

I would agree with you if this were playing with mains power, but we are talking about the low voltage side of a UL/ETL device.

i'd assume the problem there being mostly a 'tools required' problem. buying button cells in bulk is also VERY cheap.

[BobVonBob]

3 hours ago, Applefreak said:

I totally get the point of this video, even without smart controls in my house. As far as e-waste goes, I've upgraded smoke detectors from round cells to regular AA batteries. Theoretically those should last 10+ years now. You guys have 3d printers, get yourself a base for those tiny sensors, more room to work with. Btw. older 1 Amp micro b charges often times are not that hard to open up. You can directly modify the pcb inside, way cleaner looking.

Worth noting that you should change the output connection and label a power supply if you modify it. Having devices lying around with standard connections but non-standard voltages (or pinouts) is a fantastic way to blow something up.

[dogwitch]

1 hour ago, Caroline said:

If you don't want to deal with batteries or spend hours fixing design flaws don't buy useless smart devices then

oh my... we have gotten to this now.... on batteries....

[manikyath]

1 minute ago, Caroline said:

At least you said digital. The basic multimeter and ammeter are still analogue.

surprise: the analog ones still require batteries. my primary annoyance here is actually my digital calipers, which tend to be dead *right after i just ordered stuff* and they use the one type of button cell my local stores dont carry.

1 minute ago, Caroline said:

There are mains clocks. And small mechanical ones for the night table.

mains clocks are very difficult to find, they mostly exist in specific forms, which is annoying if you want a different form.

 

as for mechanical clocks.. the point of this endavour is reducing required maintenance, getting a mechanical clock is the exact opposite. (and i've had a mechanical clock for a long time, i'm aware...)

4 minutes ago, Caroline said:

Why would this need power.

should have defined 'digital' there too. i have a few digital ones dotted around because in winter our house gets very dry, so they serve as a reminder to humidify.

8 minutes ago, Caroline said:

Use mains lighting then.

again - might not be available in the form you like. mood lights / LED candles / other forms of decorative lights often only exist in battery powered form, because they only pull milliwatts anyways.

9 minutes ago, Caroline said:

Have a kid, wait until he's about 4 years old an use him to switch the channels and set the volume.

this HAS to be a joke. my only remaining use for non-rechargable AA's is the endless amount of remotes i *need* for equipment that largely doesnt even have buttons on the device itself.

[Key2300]

I love all the shit LTT makes, but after this video I had to come here (because hopefully someone from LTT staff will read this here) and make an account to ask: Does your company not have an electronics guy?

Usually watching you lot doing all kind of hackjobs to find solutions to problems is a nice entertaining journey but this felt a bit rough to watch. Someone in here said there are a million ways to go about doing this and he is absolutely right! But your first attempt, resistors, isn't one of them. And that is something that every electronics guy would've been able to tell you which is why I have to genuinely ask if your company doesn't have one. That would be a good future hire.
 

Okay, why does an attempt with resistors not work? What voltage comes out of a voltage divider depends on the load and pretty much every device has varying loads. From simple things like fans that draw more current at the start to start spinning to smart home sensors that have varying operating states that they switch inbetween. So in one moment a voltage divider will work, in the next the load will change and it won't. So in general voltage dividers can only be used for constant voltages if there is pretty much zero load on them like with NTC/PTC temperature sensors or if you need a reference voltage for an OP-amp.

Another thing that immediatly caught my eye was the lack of capacitors in all solutions. You have a very nice video about power supplies where you explain their usefulness when it comes to supplying a constant voltage. And the datasheet of the MIC5504 recommends 2x 1uF capacitors, because like every datasheet for an IC it has a typpical application section that tells customers that wanna use their part how to best implement it. They also only cost about 0,09$ a pop. Then again, okay, with how you were going about it that would've been hard to solder onto the MIC, but it could've been used in the Diode solution. But then again, for the MIC, why not use a stripboard? They cost like 3 bucks and you can cut them into several smaller ones to use them in several devices and they would've made everything SO MUCH easier! Tbh, I can't imagine that you didn't have one lying around somewhere.

I guess to conclude my criticism of the video, if the purpose of the video was to show people how to do it themselves it quite honestly failed. There would've been several better and easier ways to do this while still being dirt cheap. It felt like all solutions were results of someone googling and like no one with knowledge of electronics was involved. But if the purpose of the video was to show what someone with no knowledge of electronics and google can come up with, then I guess the video just wasn't for me.

[CoolJosh3k]

Not sure how Panasonic will feel about that thumbnail? Maybe should have photoshopped out that brand name?

[dogwitch]

3 hours ago, Caroline said:

At least you said digital. The basic multimeter and ammeter are still analogue.

There are mains clocks. And small mechanical ones for the night table.

Why would this need power.

Use mains lighting then.

 

And finally:

Have a kid, wait until he's about 4 years old an use him to switch the channels and set the volume.

 

The smug knows no limits.

just like linus dropping powers

[NumLock21]

I know that symbol on the battery is meant to keep away from children, but the more I looked at it, it looks like as if big brother is teasing his little bro from getting them batteries, where he needs it to power up his toy. So now big bro's family jewels is about to get a taste of a falcon punch.

[mariushm]

The most basic solution would have been to get a proper fixed 3v linear regulator and use it according to the datasheet (with at least a capacitor on the input, most regulators will require that, if the power source is not very close (centimeters away close). The video could have waited 1-2 days until such part arrived.

Or, an adjustable regulator could have been used along with two resistors to set the output voltage to the desired value. 

 

Another solution - which I mentioned on Floatplane as well - would have been to add a schottky diode to the output of 3.3v regulator in order to drop around 0.3-0.5v and get around 2.8-3v.

However, the voltage drop of diodes is dependent on the current going through them - when the product idles and consumes less than 1mA the diode will drop very little voltage, so a simple solution would be to make the circuit consume a minimum amount of current by adding a resistor or a "stand-by led" after the diodes, to make the circuit consume a bit of current no matter how much the sensor consumes. 10-20mA of current would be enough to get most diodes forward voltage to some reasonable values. 

 

The 3-4 diodes in series would have worked with a minimum load as explained above - you get a 1n400x diode (1n4001 to 1n4007, the difference is just the maximum voltage they can handle, even the 1n4001 can do 30v) and it will have around 0.3v at 1mA, but even at 10-20mA, the voltage drop will go up to around 0.7v  and at nearly 1A, the voltage drop can go up to 0.8v-0.9v.

So 3 x 0.7v = 2.1v,  and if you substract this from 5v, you're left with around 3v. Add a 100-210 ohm resistor across output voltage and ground to make the circuit consume 10-20-ish mA all the time and you're good.