How would you power this solenoid.

T ChapT Chap Posts: 3,885
This is a 12VDC 1/2” throw 8 watt continuous duty push type solenoid. It is going to push up an object and keep it lifted permantently except for occasions where it turns off for a minute at a time which would be once a day or maybe not at all for months. I would assume that a 1amp supply is more than sufficient. It does get hot when on. Does anyone have experience with solenoids? My question is how to get the longest lifespan from both the device and the power supply. I can provide a separate power supply for this. The Prop turns on a logic level n mosfet that is rated far above 1 amp. Just looking for advice on whether to use some much higher rated PS for longer life. Also does continuous heat mean this thing fails at some point.
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  • tonyp12tonyp12 Posts: 1,929
    edited October 25 Vote Up0Vote Down
    Something like this IC, that apply a lower hold current:
    https://www.mouser.com/ProductDetail/Texas-Instruments/DRV110PWR?qs=sGAEpiMZZMslbOXsVR1ov%2bWSD/S1HVPL
    Or with built-in mosfet:
    https://www.mouser.com/ProductDetail/Texas-Instruments/DRV103U?qs=sGAEpiMZZMtKB4wrjsn3lbJeWO/rMbZert/wGSc7LX0=

    Or you could try to simulate that with P1, but maybe with this chip maybe don't need a mcu at all?
  • Interesting. I can use a counter from the Prop to the lowside mosfet and PWM control the solenoid after initial motion. I assume the point of PWM is to reduce heat and product a longer life?
  • You probably do not want to build whatever you are building to require the solenoid to be powered up all the time.
    Better to make some sort of latching mechanism, and perhaps two solenoids, one to open and one to close.
  • Roy Eltham wrote: »
    You probably do not want to build whatever you are building to require the solenoid to be powered up all the time.
    Better to make some sort of latching mechanism, and perhaps two solenoids, one to open and one to close.

    Unless it is safety related. Energised to permit movement, de-energised to inhibit.
    Failure is not an option...it's bundled with the software.
  • Must be fail safe. Energized to stop movement, de-energize to allow movement. So if no power for any reason it is free to move. Gravity drops the solenoid pin.
  • T Chap wrote: »
    Interesting. I can use a counter from the Prop to the lowside mosfet and PWM control the solenoid after initial motion. I assume the point of PWM is to reduce heat and product a longer life?

    Yes.
    The Force-distance curve for solenoids (which includes relays) is of course non-linear.
    The holding current is much lower than the current needed to move when fully open.
    A regulated current drive is better than voltage, as the Amp-Turns is what sets the force, and that removes the solenoid temperature as a variable.

    Some designs sense the plunger position, and drive lowers when closed, and that is accidental release safer.
    Others idle at PWM and then every 5-50 seconds drive at full power for a brief pull-in-time. That gives drop-out recovery that is not as immediate, but still 'somewhat there'
    T Chap wrote: »
    Must be fail safe. Energized to stop movement, de-energize to allow movement. So if no power for any reason it is free to move. Gravity drops the solenoid pin.
    In that case, you probably need to brown-out test it, and the periodic full-pulse might be a good idea to add, easy enough if you have control of the SW :)


  • Good points. There is a lever switch that detects full on. It can be used for full power if needed. It is easy to set a periodic full power.
  • https://www.electronics-tutorials.ws/io/io_6.html

    I went looking just for grins. Always on solenoids are a thing.

    The document I linked recommended a power resistor and switch be used to limit holding current.

    Seems like pwm would do the same thing.

    Also mentioned a diode to limit back current.
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  • Can you just use a servo? Move it where you want and turn it off. Zero power consumption. Leave it anywhere for a day, a week, a year. Solenoids are terribly inefficient and non linear, and leaving one on for a month (even at reduced holding current) sounds like a bad idea.
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

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  • ercoerco Posts: 19,298
    edited October 25 Vote Up0Vote Down
    Or else get a linear actuator that switches off at either extreme. Just reverse polarity to change direction. Easy peezy.

    Or if you need cheap, use a door lock actuator. Internal rack & pinion. Just drive it for a second in either direction and shut off. Stays where you put it, and manually overrideable. $2.84 https://www.ebay.com/itm/6EB3-Auto-Car-Vehicles-Central-Locking-System-2-Wire-Door-Lock-Actuator-Motor/253780948666

    Better hurry. They had 3 and I bought one. Only two remain... and my mouse finger is itchy, those Chinese tariffs may be coming... :)
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

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  • jmgjmg Posts: 12,425
    edited October 25 Vote Up0Vote Down
    erco wrote: »
    Can you just use a servo? Move it where you want and turn it off. Zero power consumption. Leave it anywhere for a day, a week, a year. Solenoids are terribly inefficient and non linear, and leaving one on for a month (even at reduced holding current) sounds like a bad idea.

    .. unless this is part of the spec... (see above)

    "Must be fail safe. Energized to stop movement, de-energize to allow movement. So if no power for any reason it is free to move. Gravity drops the solenoid pin."

    Servos fail there, tho some designs I've seen try to fudge things with super-caps and claims those have enough energy to unlock...
    All gets complicated, and of course does not actually fail-safe at all, in all failure modes.
  • I thought about a super cap. I have used one of those giant things before. I don't mind if it takes a 30 seconds to release but beyond that it is not fail safe.
  • T Chap wrote: »
    This is a 12VDC 1/2” throw 8 watt continuous duty push type solenoid. It is going to push up an object and keep it lifted permantently except for occasions where it turns off for a minute at a time which would be once a day or maybe not at all for months.
    Use a spring to hold it up in the lifted position --- use a solenoid to push it down on the spring for the minute or so, which you said is done only occasionally.

  • You might be able to get away with simply lowering your voltage to the solenoid or obtaining a solenoid rated for higher voltage.

    We had a situation where a machine supplying 15V was powering a 12V solenoid ... for the most part this worked fine, but the solenoid did get hot and fail prematurely. ...I did some empirical testing and found that our 12V solenoid would reliably work down to 4V (33% of the rated voltage). This got me thinking and we ended up changing the 12V solenoid to a 24V solenoid on all of our machines company wide. The 24V solenoid powered from a 15V supply was perfectly happy at 62.5% of the rated voltage of the solenoid.


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  • You might be able to get away with simply lowering your voltage to the solenoid or obtaining a solenoid rated for higher voltage.

    We had a situation where a machine supplying 15V was powering a 12V solenoid ... for the most part this worked fine, but the solenoid did get hot and fail prematurely. ...I did some empirical testing and found that our 12V solenoid would reliably work down to 4V (33% of the rated voltage). This got me thinking and we ended up changing the 12V solenoid to a 24V solenoid on all of our machines company wide. The 24V solenoid powered from a 15V supply was perfectly happy at 62.5% of the rated voltage of the solenoid.
    My experience with automobiles is that if the battery is low, the solenoid can stick. This means that you try to start your vehicle and the solenoid sticks so the starter stays on --- then you have to quickly jump out, raise the hood, and disconnect the battery (hopefully you have a 1/2" wrench in hand), before your starter is ruined --- I thought this meant the solenoid was bad, and the AutoZone guy was happy to sell me a heavy-duty solenoid at double price, but when the problem continued I asked a mechanic and he told me that my battery had a low voltage of less than 12v, so I checked with a multi-meter and that was the problem.

    All in all, my suggestion of using a spring to hold the object up was correct --- it is nuts to burn up electricity, and wear out your solenoid, to hold the object up for hours or even days at a time --- a spring will hold it up, and the spring won't wear out for many years.
  • Low voltage is the #1 killer of automotive starters.
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  • Permanently energised, directional solenoid valves are pretty much the norm in the world of fluid power.
    Motors with integral brakes need to energise the brake's solenoid to allow the motor to rotate and will attempt to lock the rotor in the event of a power failure.
    Failure is not an option...it's bundled with the software.
  • We use AC solenoids in an "almost always energised" mode - the particular solenoids we used are rated for this 100% duty cycle.

    The company we use who manufactures these is ITC products, and they have a range of styles but not a huge amount of information on the net. There must be other similar manufacturers out there

    Based on about 3 decades experience, in general they are very reliable (almost never need replacing) despite being in some challenging environments. The one clear exception is a "coal loading terminal" that juts out into the sea, they seem to go through a couple per decade.

    Hope this helps.


  • Thanks for the tips. The device I am using is designed to be continuous. The offer other devices for intermittent that list a time on/ time off ratio. This one does not list any time off. However I know that it gets hot at full duty so I'm wanting to try to extend it's life else I will have to service it at some point. I can dedicate a Prop core to it, and use PWM and periodic full on, plus monitor the ON limit switch to go full power if needed. If I can get 5 years avg that will be fine. The power supply type was one concern as to what will be happy full on for years at a time. I see mag locks on doors that are on 24/7 forever so maybe it is not a big deal on a simple wall wart 12V switcher 2 amp. Those things are baking.

    https://www.mcmaster.com/70155k121
  • "We reached out to our manufacturer for the linear solenoid (70155K641) you called about, and they do not test for ways to extend/benefit the life of this solenoid. Turning down the duty cycle to less than 100% will not have much benefit to the life of the item. Using appropriate voltage and duty cycle of this product should last a fairly long time per our manufacturer."


    I think I disagree, I think if a holding duty cycle will produce lower heat that it will add to life.
  • Yeah, I think you will find that it will hold @ <50% PWM duty.
    Failure is not an option...it's bundled with the software.
  • Any frequency suggestions?
  • Reducing the voltage to the coil via PWM or a reduced supply after the solenoid is in the up position seems to be the simplest way to increase the life of both the solenoid and the power supply.
    If this was my problem to solve I would:
    - measure current draw when full voltage is applied (Ifv)
    - measure minimum current required to hold the solenoid in the up position (Ihm)
    - use a power supply rated at 2 x Ifv
    - add a constant current circuit that supplies a current half way between Ifv and Ihm
    - add a parallel circuit and a 555 timer to provide full voltage to lift the solenoid
    In science there is no authority. There is only experiment.
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  • T Chap wrote: »
    Any frequency suggestions?

    I would start with something like 1KHz. I seem to remember this being the carrier frequency of a Vickers proportional valve driver.
    Failure is not an option...it's bundled with the software.
  • T Chap wrote: »
    Any frequency suggestions?

    Will any one hear this ?
    We used 19kHz, (just ultrasonic), with deliberately soft edges on the FET, via a largish 560R gate resistor, and a fast switching catch diode.
  • Mickster wrote: »
    Permanently energised, directional solenoid valves are pretty much the norm in the world of fluid power.
    Motors with integral brakes need to energise the brake's solenoid to allow the motor to rotate and will attempt to lock the rotor in the event of a power failure.
    This is a good argument against my suggestion of using a spring to hold the object up.
    If there is a power failure you want your machine to revert to a safe state --- I mean, safe in the sense that the operator has minimal chance of getting injured --- the machine should stop moving when it is no longer under control.
    For example, brakes would be held open by the solenoid when the machine is running, but the spring would clamp down the brake when power is off.
    The OP would have to tell us more about what he is building to say which method is best.

  • T ChapT Chap Posts: 3,885
    edited October 26 Vote Up0Vote Down
    If the power is off everything must be free to move. Gravity pulls the solenoid pin back down if no power is on. I have motor brakes and clutches etc but this is a mechanical latch that stops a drive shaft when power is on. But releases the shaft when power is off. So it’s very simple. It stays on/up basically forever except for rare exceptions. If power fails it releases.

    I am going to set up a mosfet off the prop and test various frequencies and see how it behaves. I looked online at constant current methods and see the lm317 being used quite a bit. Very simple to make. The device is pulling .666 amps.
  • This is what I use as a solenoid driver
  • I forgot the feedback line in the original schematic. Corrected version.
  • T Chap wrote: »
    I am going to set up a mosfet off the prop and test various frequencies and see how it behaves. I looked online at constant current methods and see the lm317 being used quite a bit. Very simple to make. The device is pulling .666 amps.

    That current is pushing things for linear regulation.
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