How hot should a 12v 8w 0.6a solenoid valve coil get??

[PhatFil]

I am using my first 12v 8w 0.6a 1/2" solenoid valve (gravity fed 0-0.08mpa back pressure required) its completely isolated from the Pi -0-w that will be controlling it via node red and other systems it hosts. its connected to a wemos d1 board fitted with a 7-24v power supply shield and a relay shield.

the wemos d1 board assembly is fed by and switches 12v dc from a 1.5a dc psu. (so 0.6a valve draw 100ma for the electronics, well within the 1.5a capacity of the psu?? old netgear usb hdd psu)

after a minute or so of operation the solenoid coil it getting too hot to touch while operating as expected?? is this normal?? Nothing else is getting unexpectedly hot, and the valve continues to operate as expected only heating up when switched on.

However the amount of heat generated by the coil is stopping me from testing for any longer than a minute or so..


In use (filling a ground level water tank from rain butt ) It may be required to operate for significantly longer than 60 seconds or so..

[davidcoton]

Check the valve manufacturer's data. It will be dissipating 8W, of course. My 10W soldering iron gets hot enough to melt metal...

It is possible that the solenoid is designed to be cooled by liquid flow. This means you may have to detect either or both of low water butt level or solenoid overheat and shut down under those conditions.

[Brandon92]

Is that solenoid also rated for 100% operation. And not for a x amount of time it can be on. And then he need to be turned of for a x amount of time.

And did you get the right part and not a coil that is rated for a different voltage?

[PhatFil]

Thanks for the input, its my first time playing with such a device. I did wonder about the 8w ratting, I dont think liquid cooling is part of the equation the coil sits atop a plastic housing and indirectly pulls/pushes? on the valve diaphragm.. here is an ebay ad for a similar product with a different back pressure requirement.
https://www.ebay.co.uk/itm/1-2-Plastic- ... rk:32:pf:0
perhaps its just expected to radiate the excess heat ?? perhaps extend the test duration by 30 seconds at a time monitor the actual temps reached and keep an eye out for magic smoke release..

[PhatFil]

Is that solenoid also rated for 100% operation. And not for a x amount of time it can be on. And then he need to be turned of for a x amount of time.

And did you get the right part and not a coil that is rated for a different voltage?

I read the 12v directly off the coil label,afaik they can come in a 24v too? and i have not seen ads for anything with a lower voltage, though that means little i did also dbl check the wemos d1 assembly output too and its 12v .. as for any duty cycle requirements i have no idea, its a ebay bargain device similar to one linked to in my above reply.. I cant recall any mention of duty cycles in any ads i looked at before buying..

[Brandon92]

Okay, that a solenoid can get hot is normal. But how much is often the question. I would test how hot is going to get. And check if that is acceptable for you. Because the current is still within the specifications.
Here is one with a similar problem: https://forum.allaboutcircuits.com/thre ... ot.118698/

And it could also be, you get what you paid for, kind of story.

[boyoh]

I am using my first 12v 8w 0.6a 1/2" solenoid valve (gravity fed 0-0.08mpa back pressure required) its completely isolated from the Pi -0-w that will be controlling it via node red and other systems it hosts. its connected to a wemos d1 board fitted with a 7-24v power supply shield and a relay shield.

the wemos d1 board assembly is fed by and switches 12v dc from a 1.5a dc psu. (so 0.6a valve draw 100ma for the electronics, well within the 1.5a capacity of the psu?? old netgear usb hdd psu)

after a minute or so of operation the solenoid coil it getting too hot to touch while operating as expected?? is this normal?? Nothing else is getting unexpectedly hot, and the valve continues to operate as expected only heating up when switched on.

However the amount of heat generated by the coil is stopping me from testing for any longer than a minute or so..


In use (filling a ground level water tank from rain butt ) It may be required to operate for significantly longer than 60 seconds or so..

Check that it is not a AC Solenoid that you are using

[drgeoff]

I am using my first 12v 8w 0.6a 1/2" solenoid valve (gravity fed 0-0.08mpa back pressure required) its completely isolated from the Pi -0-w that will be controlling it via node red and other systems it hosts. its connected to a wemos d1 board fitted with a 7-24v power supply shield and a relay shield.

the wemos d1 board assembly is fed by and switches 12v dc from a 1.5a dc psu. (so 0.6a valve draw 100ma for the electronics, well within the 1.5a capacity of the psu?? old netgear usb hdd psu)

after a minute or so of operation the solenoid coil it getting too hot to touch while operating as expected?? is this normal?? Nothing else is getting unexpectedly hot, and the valve continues to operate as expected only heating up when switched on.

However the amount of heat generated by the coil is stopping me from testing for any longer than a minute or so..


In use (filling a ground level water tank from rain butt ) It may be required to operate for significantly longer than 60 seconds or so..

Check that it is not a AC Solenoid that you are using

That is very good advice. A solenoid designed for AC will take appreciably more current if used on DC.

[PhatFil]

Thanks for the input and links, I am pretty sure its DC voltage (assuming the label is correct) its about all the label does tell me,,

I did buy the cheapest valve that would operate with a limited gravity fed head, so thats probably at the root of this..

reading through some of the posts in the link above it seems it might be worth testing if a lower voltage will also switch the valve, that i can do..

this was supposed to make things simpler,, currently a float/ball valve controls the flow from a waterbut into my greenghouse watering 'sump tant' (10-15l) which gets pumped upto the bench height with a water feature pump to drain through germinating seeds and back down into the sump tank. seed trays can dry out in no time with a short sunny spell under glass, killing the seeds off .

the problem being that while the pump is starting to drench the seed trays and no water is draining back the float valve releases more and often too much water into the sump tank. So when the water does drain back it can often overflow and waste. and the whole point is to use my limited rain water supply wisely.

so the idea was insert a solenoid valve to close off the supply while pumping. With hindsight perhaps a Normally open type valve would have been a better option,, Back to the ol drawing board ....

(i think i will buy or look for a bigger sump tank bury it a little deeper and fit the float valve lower down so any excess that drains in is still contained.. )
.