USB powerring of Fibaro battery operated devices

[Bodyart 231]

Has anyone some experience with powerring battery operated devices?

there are many step down converters in the market converting 5V DC (USB charger) to 3,3V DC - suitable for different battery operated Fibaro modules.

Has Anyone tried this? Although after this modification the device will be still recognised by HC2/HCL as battery powerred, it can be a solution in some situations where powerline is present and we can then forget about checking batteries

 

[AutoFrank 372]

42 minutes ago, Bodyart said:

Has anyone some experience with powerring battery operated devices?

there are many step down converters in the market converting 5V DC (USB charger) to 3,3V DC - suitable for different battery operated Fibaro modules.

Has Anyone tried this? Although after this modification the device will be still recognised by HC2/HCL as battery powerred, it can be a solution in some situations where powerline is present and we can then forget about checking batteries

 

 

Hi @Bodyart

I have used some 5v laptop power supplies to power two everspring motion sensors SP103

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I decided recently to recently to redo these and only yesterday purchased some of these

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The sensor normally takes 2 x AA batteries

I'll feed the above unit with 5V from a USB power supply and adjust the output to give 3v

 

Two AA batteries side by side take up about 50mm x 30mm

These devices are 22mm x 17mm so I should have no issue fitting into the battery compartment.of  the sensor

I'll solder USB lead to the input of the step down unit and the output directly to the sensor PCB

 

It's untried as of yet but I reckon it should work okay

 

normally @petergebruers is the expert at these sort of thing...

 

 

[jimicr 90]

I can't find it at the moment, but I remember reading on the french forum about a guy who made fake wooden batteries to run the wires to the sensor so you don't have to solder them. 

[petergebruers 1,265]

17 hours ago, AutoFrank said:

It's untried as of yet but I reckon it should work okay

 

normally @petergebruers is the expert at these sort of thing...

 

Thanks for the compliment...

 

I know that module, I own several of them. I'd recommend it for "general use" but not for this application. It is an SMPS so it is quite efficient when dropping a lot of voltage, e.g. 12 V in and 3.3 V out. I'm not sure, but because it operates at high frequency, it might introduce noise in the sensor... It might have issues with some loads if Vin < 5.0 V but there is a fix for that, contact me if you want details. After you adjust this module, I recommend a drop of nail polish on the trimmer to protect it, these trimmers can develop intermittent contacts over the years and because they are in the feedback loop, this can cause over-voltage.

 

If you power a module rated < 100 mA (that would be most of them)  on USB then I'd go for ancient technology at unbeatable price, the Chinese AMS1117 clones.

 

Smaller, cheaper (1 dollar for 5 pcs) and low noise:

 

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Also buy some heat-shrink tubing for the module. Watch out for the unusual pin order: in - out - gnd and not in- gnd out!

 

I'd be careful if I wanted to implement an alternative power source... Battery operated device do not always contain voltage regulators, so connecting 5 V exceeds the spec of the chip (max 3.6 V). 

 

Also connecting a freshly charged 3.6 or 3.7 V is not recommended, those can have 4.1 V even when loaded with the 40 mA of the module... It doesn't immediately fry a Z-Wave chip and there will probably be some sort of voltage drop internally because of reverse battery protection on the module, but it still exceeds specification.

 

You can use LiFePo4 cells, often advertised as 3.0 V (that's 3.2 - 3.3 V). Be careful, cheap cells often do not have much protection. Except vents or over-current trip circuits but you do not want to trigger these!

 

But before going the rechargeable route, ask about the disadvantages

 

48 minutes ago, jimicr said:

I can't find it at the moment, but I remember reading on the french forum about a guy who made fake wooden batteries to run the wires to the sensor so you don't have to solder them. 

 

Yes... A copper nail on one side and some copper tape on the other side (expensive). I use a cork, after drinking the wine or beer. Nice hobby project... Winter is coming

 

[Bodyart 231]

I'm planning to use   AMS1117-3.3 Power Module AMS1117 3.3V Power Supply Module With Heat Sink placed "far" from fibaro device and ferrite core applied on the cable

 

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available on

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[petergebruers 1,265]

@Bodyart thanks for sharing!

 

It is not forbidden to use a heatsink, but you do not need one for this application. Assuming 100 mA max (typical: 40 mA)  and 1.7 V drop is only 0.17 W dissipation. The board can do 0.5 W.

 

Ferrite core on a cable reduces EMI or earth loop current, not voltage noise of the supply. It probably won't do much, assuming your 5 V adapter is from a known brand, so it rmeets EMC regulations... If you already have one, it might be interesting to find out if it makes any difference. For instance, do you get more stable readings from your sensor?

[Bodyart 231]

I do not have one yet, but i will test it ofcourse for sure, when i get one.

Some tweakers on

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(in Dutch) stated that the module without heatsink became pretty warm used for Fibaro motion sensor...

[petergebruers 1,265]

4 hours ago, Bodyart said:

stated that the module without heatsink became pretty warm used for Fibaro motion sensor...

 

That should not be the case.

 

First, let's establish what "warm" is:

• Human beings: 40 °C = bathwater temp
• Electronics devices = 75 °C = "ouch"  for human beings
• Too hot for electronics & humans : die temperature 125 - 175 °C, depending on thermal conductivity to the surroundings, that means burned fingers.

Assuming it is somewhere between 40 - 75 degrees, this cannot be caused by the motion sensor, because it will be sleeping most of the time. The AMS1117 uses about 5 - 10 mA, that cannot explain the heating.

 

I'm 99% certain that almost all cases of mysterious heating of linear power regulators is caused by oscillation. One possible cause of instability is that they use ceramic capacitors on the board, while some clones of the AMS1117 do not support this. Those versions do not like capacitors with ESR < about 0.1. Or maybe the capacitance is too low, the datasheet mentions 22 uF. Low cost ceramics often lose a lot of capacitance with voltage, so a 22 uF nominal could end up being 1/2 or even less than the recommended value. The latter problem can be solved by adding a capacitor. Or, I am thinking out loud, maybe the capacitive loading of the module makes the regulator oscillate... Did they measure the voltage? If it deviates by more than a few %, oscillation is a very likely cause. But beware, some regulators can maintain an average of 3.3 V while this output swings between (almost) Vin and GND! Definitely not good for your sensor! Luckily, this regulator always drops about 1.0 V, but if you connect Vin to 12 V and it oscillates, bad things could happen...

 

An oscilloscope could solve this mistery...

 

I'll dig up one of those boards and connect it to a motion sensor. Let's see what happens...

 

Edit: the AMS1117 is an improved version of the LM1117. The older chip has this line in the data-sheet: "The ESR of the output capacitor should range between 0.3 Ω to 22 Ω". The AMS1117 does not mention this, it is newer and stable with a wider range of caps. Another variant (a good one) is the NCP1117 by On Semiconductor. It requires ESR > 0.02 ohm. Rare for electrolytics, but MLCC type capacitors can have lower ESR than this...

Edited October 28, 2017 by petergebruers

[Bodyart 231]

@petergebruers,

 

looking forward to your test results.. Maybe I'll buy cheaper version without heatsink

 

[Jamie mccrostie 82]

5 hours ago, petergebruers said:

 

Thanks for the compliment...

 

I know that module, I own several of them. I'd recommend it for "general use" but not for this application. It is an SMPS so it is quite efficient when dropping a lot of voltage, e.g. 12 V in and 3.3 V out. I'm not sure, but because it operates at high frequency, it might introduce noise in the sensor... It might have issues with some loads if Vin < 5.0 V but there is a fix for that, contact me if you want details. After you adjust this module, I recommend a drop of nail polish on the trimmer to protect it, these trimmers can develop intermittent contacts over the years and because they are in the feedback loop, this can cause over-voltage.

 

If you power a module rated < 100 mA (that would be most of them)  on USB then I'd go for ancient technology at unbeatable price, the Chinese AMS1117 clones.

 

Smaller, cheaper (1 dollar for 5 pcs) and low noise:

 

Please login or register to see this link.

 

Please login or register to see this link.

 

Also buy some heat-shrink tubing for the module. Watch out for the unusual pin order: in - out - gnd and not in- gnd out!

 

I'd be careful if I wanted to implement an alternative power source... Battery operated device do not always contain voltage regulators, so connecting 5 V exceeds the spec of the chip (max 3.6 V). 

 

Also connecting a freshly charged 3.6 or 3.7 V is not recommended, those can have 4.1 V even when loaded with the 40 mA of the module... It doesn't immediately fry a Z-Wave chip and there will probably be some sort of voltage drop internally because of reverse battery protection on the module, but it still exceeds specification.

 

You can use LiFePo4 cells, often advertised as 3.0 V (that's 3.2 - 3.3 V). Be careful, cheap cells often do not have much protection. Except vents or over-current trip circuits but you do not want to trigger these!

 

But before going the rechargeable route, ask about the disadvantages

 

 

Yes... A copper nail on one side and some copper tape on the other side (expensive). I use a cork, after drinking the wine or beer. Nice hobby project... Winter is coming

 

Ive herd of a Lego block being used for battery space replacment

Edited October 28, 2017 by Jamie mccrostie

[petergebruers 1,265]

I cannot make my AMS1117 run hot... Not by adding capacitance, not by adding inductance (simulating long wires). I tested it on my Z-Uno which running an always-on sketch so it consumes 40 mA. It stays cold to the touch!

 

So I need more information to understand why some people reported their board ran hot. A heat sink is not a good solution, it hides the true problem...

 

Maybe I got lucky and I got better chips. Mind you, I cannot guarantee you get the same boards as me, mine are several months old.

 

This is from  reliable seller, the board has a different form factor. It is a bit bigger, but you get nice separation of "in" and "out". This board has no components on the back, but it does have copper so it acts as a heatsink...

 

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[Bodyart 231]

Just a simple minded thouths.... Why are they making heatsinks on it, when it only consumes 2,64W max?

 

[petergebruers 1,265]

27 minutes ago, Bodyart said:

Just a simple minded thouths.... Why are they making heatsinks on it, when it only consumes 2,64W max?

 

 

The junction should stay below 125 °C under normal operation, say 100 °C above room temperature. Assuming you get enough air circulation, this is a valid assumption.

 

The datasheet mentions if you have 10 x 10 mm copper, junction to ambient is 55  K/W so I'd say it reaches thermal limit at 1.8 W. I'd say the smallest version, in a confined space, should be limited to about 1 W.

 

If you have lots of copper... they estimate 45 K/W so that is 2.2 W...

 

If you add a reasonable sized heatsink, you can get 30 K/W, this equates to 3.3 W... That is a lot for this package, but they say it is possible.

 

I think the heatsink on that model looks good, but is not very useful indeed.

 

You mention 2,64 W and that is 0.8 * 3.3 V. This is not the power dissipation of the 1117, it is the power dissipation of the load.

 

Power dissipation of the regulator = I * (Vin - Vout). If you assume a 5 V supply and max 0.8 A then P = (5.0-3.3)*0.8 = 1.36 W.

 

If you have a 12 V supply and assume maximum current: (12.0-3.3)*0.8 = 6,96. This exceeds the thermal capabilities. So at 12 V with that heat sink, current should be limited to 3.3/(12-3.3) = 0.38 A.

 

Does this help?

 

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EDIT: chip powers down if the junction exceeds a certain temperature, it is probably around 150 - 175 degrees. For continuous operation, they recommend 125 degrees max...

Edited October 28, 2017 by petergebruers

[Bodyart 231]

Thank you @petergebruers,

it was clear and helpful too. Thanks again.

 

[AutoFrank 372]

Hi @Bodyart, @petergebruers

 

My batch of AMS1117 arrived this morning and I hope to get to connecting it up over next few nights and will report back

My first target is an Everspring SP103 Motion sensor that has been offline for a while now

 

 

[Jamie mccrostie 82]

3 minutes ago, AutoFrank said:

Hi @Bodyart, @petergebruers

 

My batch of AMS1117 arrived this morning and I hope to get to connecting it up over next few nights and will report back

My first target is an Everspring SP103 Motion sensor that has been offline for a while now

 

 

Im watching with interest .