Shelly 1PM gets hot

Hardware
1

Got two Shelly 1PM, flashed with tasmota, calibrated on 60W bulb, everything works.

Week ago attached one to air conditioner which uses 1500W (7A):
when off shelly temperature is 50-60c at 25c room temp
when on shelly temperature gets to 75c after an hour and then heating cycle ends so shelly cools
seems bit high but as long as it gets to 75c max I’m ok with it.

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Now attached one to water heater which uses 2600W (12A):
when off shelly temperature is 50-60c at 25c room temp
when on shelly temperature gets to 90c after 20 minutes and turns off by itself.

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I’m using them only for monitoring power consumption not for controlling devices.

Wired them both according to shelly instruction like this:
a

What could it be source heating problem? 12A should be ok on 16A switch

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You might have a better time finding an answer on the Shelly support group on facebook

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The source is mostly from R*i^2 losses in the pcb traces and current sensor itself. 12A should be ok on a 16A shelly 1pm, but in reality there are situations where that is too much. In your case 12A is clearly too much. I have seen the same with the UL listed shelly 2.5, where it shuts down at even lower currents during summer time (when exterior walls get hot). Bottom line, proof is in the pudding. Shelly may be claiming their ratings based on operation in free air, or something like a simulated temperature controlled wall cavity. Unfortunately that is not going to mimmick realities of a random j-box somewhere in a random house, in a random climate, with random insulation and climate controls. There are some legal j-boxes in our country that get hotter than 60C without anything causing heat other than the sun. You’d have to have quite the “shelly” to measure/switch 16A in those situations… it is feasible, but shelly isn’t doing it.

At least they were good to put a thermal shutdown in there; this precludes having houses catch fire when you find out the device is inadequate. For me, I could call shelly and demand returns etc, but there are other situations I can use the devices around home where they won’t overheat… so I usually go that road when a shelly overheats on me. Would be nice to return to a world where advertising and claims were scientifically based, but I feel that is lost these days (like Subaru selling cars for the love, not the lower CG provided by the boxer configuration)… especially with heavily marketed products like shelly.

1 Like
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@BrendanMoran made post in shelly forum but is very small forum so I’m not counting on solution

@truglodite I hope its some configuration issue and not flaw by design

Read that Shelly 2.5 had heating solution with tasmota previous versions and fix was to assign something to GPIO16 which lowered temps by 15c but it uses different power monitoring chip than 1pm

Maybe similar issue here I shoud test them with original firmware

5

Why do you have L permanently connected to SW?
Not saying it’s the reason of overheating but it can be potentially… anyway this connection is not needed at all. in fact it looks strange…

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@maxym At first they were connected like this:
b

But then I read it’s not according to shelly instruction so I chenged it
https://shelly.cloud/knowledge-base/devices/shelly-1pm/

Anyway temperatures are the same

7

Your second image is correct considering you don’t want to use switch.
I know Shelly docs well. no one suggest to connect L to SW in permament way. Don’t know where you took it from.

I have 1PM mounted behind wall socket, and currently it has 44C in idle.

BTW I have feeling you do things blindly not even trying to understand what is going on. remember, electricity is dangerous and can kill you.

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The facebook group has 25k members, Redirecting...

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@maxym Idle I get about 50c, did you try it with load more than 10A over long time?

@BrendanMoran I don’t have face account

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Only washing machine but it takes 10A for short time only while heating water.

Anyway I’m pointing you to the fact your connection is wrong. Fix it and report back if it helped

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@maxym You said this is correct:
b

It was connected like this when measurements taken, only now when connected the second shelly and saw it was heating I changed connections

Both ways work and both ways gives same temperatures so it’s not wiring problem

I suspect tasmota like in this in this post so other shelly model:

My intention is to try them with original shelly firmware, I’ll report when done

12

According to shelly operating temperatures:

  • The maximum ambient temperature may be 40 degrees.
  • Without load, the operating temperature is 55-60 degrees.
  • With MAX load, the operating temperature can rise to 87-90 degrees.
  • The heat protection switches off the device at 95 degrees.
  • All parts inside are designed for 105-120 degrees, and certified for continuous use.

https://www.shelly-support.eu/lexikon/index.php?entry/85-operating-temperature/

With tasmota they turn off at 90c by default cause I haven’t changed anything, by looking at temperature graph rising pattern seems it won’t stop at 95c cause it’s not even starting to stabilise:

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12A is quite a heavy load, I’m not too surprised that it heats up. The plug of a 1500W (120V) space heater gets quite hot in normal operation, 60C+ is not unusual. It’s good to be vigilant though, electricity can and does start fires, and you have to be particularly careful when dealing with large loads. Any resistance will result in a voltage drop and a voltage drop results in heat. That heat can damage contacts or cause cracks in solder joints which results in more resistance and more heat and you can have a thermal runaway situation. Personally I don’t like to operate devices like this continuously beyond about 50% rated capacity, and certainly not beyond 80%. I think Shelly is a notch or two above the random dirt cheap stuff like Sonoff but it’s still not established like Leviton, Lutron, Eaton, etc.

What I would do is first try a second unit powering the same load and see if it also runs hot, and if it does, try to determine what component is getting hot. If it’s the relay itself for example you could look up the datasheet for the specific relay they used and see what the specified rise is under full load. Temperature rise is entirely down to load and resistance, the firmware on the device cannot affect this, it can only affect the response to a temperature rise.

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14

Then use a device that is specifically designed for power consumption monitoring, like the Shelly EM. 12A is getting into a range where current clamps are much better suited than a small shunt resistor enclosed in a cavity without much cooling.

1 Like
15

Does anyone know how the 1PM behaves when used while charging a PHEV. The load will be around 10 amps for 8 till nine hours with a granny charger.

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I suggest to ask on Shelly’s FB

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10A, for 8 hours, and charging is typically over night…

I am not you, but personally I would rather be safe and not risk my house with something that would run hot and is known to be hot… (even 60C at idle no load is kind to too much also.)

I would use something with a CT clamp, such as maybe a Shelly EM, or use something that is rated to handle 24A, 30A, or 40A.

18

Please note the screen shot where I am monitoring all my Shelly temps on my phone. I am not happy with how a few have a tendency for spikes up to 130 degrees F… More details are below the picture and if you folks that have alot of shelly’s could, possibly let me know your thoughts on Shelly temps in general?

Screenshot_20230220-142449_Home Assistant
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It is a pretty warm but still winter here (35-55 degrees F typically outside right now). Everything is in F. These are current temp graphs the last 24 hours, going left to right starting at the top (picture shows only current temps). Old home, does have single zone central air and heat (but lousy insulation so a room on one floor can be 5 degrees different from a room on another floor!):

For each graph, I am giving details on the graph max and min and what/where it is for each:

107.4: (Max 116.96, Min 104.89) Raspberry PI 64bit debian HA “Server” - not a concern (in a nice cold basement)

115.3: (Max 130.65, Min 113.63) Shelly +1 Relay, in a very tight metal receptacle, interior house wall, wall switch for a small kitchen which often gets pretty hot from cooking…

120.0: (Max 131.33, Min 119.4) Shelly +1 Relay, in a metal 2-gang receptacle (which is very crowded) for a foyer (but a completely internal wall in an area that does not get very hot). It is behind an old dumb switch but sits next to a wemo switch in the same metal receptacle.

91.0: (Max 95.22, Min 77.61) Shelly 1L Relay, inside the home but on an exterior wall for two incandescent lights outside the home, has no neutral and no bypass but works fine without it).

122.2: (Max 129.18, Min 99.53) Shelly 1L relay, no neutral in a metal single gang wall receptacle on the first floor (one of two wall light switches - one at the bottom and one at the top of a set of stairs) controling a ceiling light fixture at the top of the stairs - was a PITA figuring out the wiring but works like a charm. Having trouble getting a decent bypass from Shelly in the USA so to avoid flicker the 4 bulbs in the receptacle are incandescent - no bypass but no flicker, works fine.

90.7: (Max 111.79, Min 89.12) Shelly 1L relay behind a very old dumb wall switch in a small metal receptacle, small bedroom that is only used occassionally and is in a cooler part of the home on the second floor, controls an outlet into which a power strip is plugged which is powering several lights. A non-shelly bypass is in the outlet, but there still is a little flicker so a couple of the lights were switched to incandescent for now.

These last two on the bottom row are the same Shelly 2PM, it may be silly to bother reporting both as they would most likely forever be the same:
89.4: (Max 90, 73.6) (forgot to add this is managing a dual receptacle on the side of an uninsulated garage, one edge switch (which controls a spotlights above a outdoor barbecue area) and one outlet (and there’s an rc snubber on the outlet for goog measure, but rarely used, just for xmas lights, occassional hedge clippers and the like).

So, what do you folks suggest, the manuals for these state the normal operating temp is max 40C which I believe is 120F. Almost all the time mine are within the accepted ranges except for an occassional spike to 130 or 131. Is there any kind of setting that I can use on these that will minimize their temperature (I did have some connectivity issues early on when learning how to configure them so I have power saving OFF) - I can reply back with that turned on but is this normal? (I do not use MQTT for these, only static IP’s. We are empty nesters so the relays don’t even go on or off very often throughout the day (triggered by motion sensors) - all swtches are set to “edge”… ?

Thoughts?

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130F (around 54c) isn’t something that is immediately concerning, especially if it only happens in short spikes. It won’t start a fire. Insulator fire ratings are way above that (usually around 195F / 90c). If your Shelly goes up to 140F (60c) or above, for longer periods of time, then I would start getting concerned. 75c (167F) as reported by the OP above is absolutely too hot and can actually be above the self-ignition temperature of some old, non-code compliant insulation (old houses can still have that).

Not really. These temperatures do not come from the microcontroller, at least when using stock firmware. They come from the power measuring shunt resistor. The more current you push through it, the higher the losses in the shunt and the higher the temperature. For higher loads, these small modules with resistive power measuring are totally inadequate. I personally think that they should be illegal. Devices working with CT clamps are much better suited for this task and won’t heat up at all regardless of the amount of power they measure.

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I made sure mqtt was turned OFF and thet ECO mode is turned on for all of them, and that helped dramatically, they are all running much cooler. I’ll post another screen shot after another 24 hours. @HeyImAlex, my loads are very low so I feel your solution is overkill (and making them illegal is WAAY overkill!).