I'm providing a slow-closing solenoid valve for a hydroelectric system in a village in the Philippines. I need to have the normally closed valve activated to open when the batteries are drained to a certain level.

The current system (without a solenoid valve) is a mile-long pipe descending from a small pond. During the operational season, it runs 24/7 and the system for bleeding off the produced energy keeps getting fried. So we are thinking the solenoid would prevent that problem and decrease wear and tear on the hydro system.

I'm out of my league here and could use some ideas asap. Thanks.

  • \$\begingroup\$ Don't forget to work out where the water will go when the valve is closed. \$\endgroup\$ Commented Sep 11, 2018 at 3:48
  • \$\begingroup\$ I think they were planning on just letting the water flow down the creek, the "pond" is man-made in a creek bed. I will have to check to see how full the pipe is as it flows through the system, because that could add tremendous weight over a mile of pipe. \$\endgroup\$
    – Ty T
    Commented Sep 11, 2018 at 5:35
  • \$\begingroup\$ +1 on what @immibis said. "mile-long pipe descending" is a huge amount of energy which needs to be handled when you turn off the flow. \$\endgroup\$
    – winny
    Commented Sep 11, 2018 at 8:11
  • \$\begingroup\$ I was referring to what Ty was talking about (the water continues flowing down a creek). I expect that closing the valve slowly enough will prevent the water's inertia causing any problems, but you're right @winny, I didn't think of that. \$\endgroup\$ Commented Sep 11, 2018 at 8:20
  • \$\begingroup\$ @immibis Slowly only means you will dissipate the energy over a longer time. You still need to snub away all the energy somehow. Here is a picture of my local hydropower plant. Long pipe (L) and two huge reservoirs (C) close to the lid (switch), forming a lossless or RC snubber depending on how you look at it. geocaching.com/geocache/… \$\endgroup\$
    – winny
    Commented Sep 11, 2018 at 9:28

1 Answer 1


I would suggest using a simple microcontroller do the job.

For ex: using an 'if' function using two variables as so would help

  • \$\begingroup\$ Are you aware of a commercially-available microcontroller that would be user-friendly for my friends in the mountains of Palawan that could perform this function? It would need to be connected in some way to a battery charge monitor, no? Fortunately, they are more familiar with electronics than I, but can't get their hands on much in their remote area. So I scrounge stuff up and ship it to them with funds we've raised for their project. Thanks for your answer, by the way. \$\endgroup\$
    – Ty T
    Commented Sep 11, 2018 at 5:41
  • \$\begingroup\$ perhaps it would be better if I asked for a 2 or 3 companies that are well-known for items that would meet my need \$\endgroup\$
    – Ty T
    Commented Sep 11, 2018 at 7:47
  • \$\begingroup\$ use an arduino knockoff, it would be very cheap, and easy get things done \$\endgroup\$ Commented Oct 31, 2018 at 17:34

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