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Say that I have a 12VDC 2A rated solenoid, but I test the lowest voltage that my solenoid operates reliably for my specific application. Could I just operate the solenoid at this lower voltage to extend the life of the coils?

This question came up because I received a 12VDC (2A) solenoid valve before receiving the power supply, so I tested it with a lower rated power supply and read 8VDC and 1.7A during operation. Then I installed the 12V supply and during operation it reads 11V 2A (what it's rated for).

But that got me thinking, this solenoid gets really hot. Wouldn't it be happier operating it at a lower voltage if it works just fine?

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  • \$\begingroup\$ Are you using it within the specification provided by the manufacturer??? If you feed it the 12V 2A they ask for, their rated lifetime should apply. What's the datasheet say? \$\endgroup\$ – Kyle B Aug 11 '20 at 19:44
  • \$\begingroup\$ What's "really hot" to you? A solenoid is a hunk of wire and steel; depending on the insulation they use it could run hot enough to burn you but still be plenty cool to last 100 years. \$\endgroup\$ – TimWescott Aug 11 '20 at 20:38
  • \$\begingroup\$ And -- check to see if it's designed for continuous or intermittent operation. If it's designed to hold all day every day then you're fine, stop worrying. If it's designed for some low duty cycle (e.g. pulled in 10% of the time, no more), then pay attention to the data sheet. \$\endgroup\$ – TimWescott Aug 11 '20 at 20:40
  • \$\begingroup\$ I didn't particularly purchase a high-end solenoid valve, so it doesn't specify lifetime (they do give a 1 year warranty so... fingers crossed for much longer than a year). Datasheet is very limited, so unfortunately I didn't find anything about intermittent or continuous duty (contacting the supplier just said "placing a fan will extend coil life"). The conflict I have is that this will be housed with other electronics with lower operating temp ratings--I plan to run it while keeping an eye on the air temp inside, but my mind wondered off into planning on combating the heat. \$\endgroup\$ – Esteban Aug 12 '20 at 2:02
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In general that is true, however you may find that the plunger gets crudded up with dirt and possibly magnetic particles during the life, so it fails to operate.

Also note that solenoids respond to current, not voltage, so if your coil is very hot (if it feels hot on the outside, the inner part of the winding is quite a bit higher in temperature) the current through the coil will drop substantially and it may not perform the desired function until it is allowed to cool. This can be exacerbated by high ambient temperature. That's because copper wire (most likely the wire in your solenoid) increases resistance by about +0.4%/°C.

If you want it to run cooler, you may be able to start with a higher voltage and then decrease the voltage after the solenoid has pulled in. The "holding" current is substantially less than the current to get the plunger to move initially, particularly if it is a type that closes the magnetic circuit.

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The better way would be to apply a 12V DC pulse and then maintain a lower holding voltage. PWM control may also be used to achieve that.

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