I bought this solenoid from ebay and was wondering how to power it.

It says 12 volts as you can also see from the picture, but I tested it with putting a 9V battery straight to its terminals for a while, the solenoid and battery got hot after a while.

I measured it with a multimeter and it read 9.0 ohms. Putting the multimeter through it measured 0.53 amps. Both with 9V battery

If I had battery eliminator that gave 12V output, what other components would I need to make it not go hot? Do I need some resistors?

And is it possible to get its power usage to a minimum with it still opening using various components?

Can I add lots of resistors and the voltage remains 12?

  • 2
    \$\begingroup\$ You could contact the manufacturer (from china [sic]) and ask them how to drive their solenoid, and why is it getting hot, and whether or not that is a problem. \$\endgroup\$ Mar 31, 2014 at 22:24
  • 3
    \$\begingroup\$ It being April 1 now, I can only say that if you don't live in China you will need very long wires. \$\endgroup\$ Apr 1, 2014 at 8:09

2 Answers 2


If the coil resistance is 9 ohms, it should draw 1.33 amps at 12 volts, and dissipate 16 watts - so it will get quite hot. That current is much more than a common 9 volt battery can supply - from the current you mention, the battery voltage will be about 4.8 volts when trying to drive the valve.

Despite the eBay ad's claim, I suspect it may actually be an AC solenoid. On one dealer's website, I see coil powers for that size valve stated as 3 - 6 watts.

Adding resistors in series with the coil won't help - it will just reduce the current, and the voltage across the coil.

  • 3
    \$\begingroup\$ If it is A DC solenoid it may not be rated for continuous duty- It might be intended to actuate something for a short time. Without the manufacturer's data it's hard to know. \$\endgroup\$
    – John D
    Mar 31, 2014 at 22:41
  • \$\begingroup\$ Yup, goes to show. I think i will buy a solenoid from another supplier with more info etc. Thanks! \$\endgroup\$
    – user6529
    Mar 31, 2014 at 22:44
  • \$\begingroup\$ @user6529 EE.SE golden rule: "No datasheet = No sale." \$\endgroup\$ Mar 31, 2014 at 23:15
  • 1
    \$\begingroup\$ @user6529 and don't buy Chinese junk on eBay (or any electronic component really) \$\endgroup\$
    – Matt Young
    Apr 1, 2014 at 1:55

Some solenoids current limit when switched correctly. Probably not this one, but you wouldn't know, would you? 9V is rather less than 10.8V, the rated minimum voltage.

Looking at it, I would guess that the way to keep it cool when switched open, is to run something like water through the valve when it is switched open.

  • \$\begingroup\$ But they are claim this valve it is suitable for Gas as well, or maybe can control hot water. Have you any data from manufacturer, or it is a guess? \$\endgroup\$
    – GR Tech
    Apr 1, 2014 at 12:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.