Automatically activated battery backup air pump (or anything really) - FOR CHEAP!

Hello!

I was up waaaaay to late the other day and dinking around on Amazon, usually not a great combination BUT I had an idea. I have been wanting to get a battery powered air pump for a while now just to have SOMETHING to use in case a power outage. I have a UPS on my computer and figured I could always use that but it sounds like they are rather inefficient at low wattage so it would not power even an air pump for long.

Now there are battery powered air pumps out there, but I wanted one that would detect power loss and switch on automatically, these also exist, but why buy one when you can make it? Especially if you A) Already have a battery operated pump, or B) you want to do even MORE things when the power goes out.

The secret is in a AC sensing relay, I bought this one as its cheap, pre-packaged and has a lot of nice saftey features already built in:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I de-soldered a connection inside the pump that went from the battery pack to the motor, and put the relay inline, one wire to the common rail and the other to the 'normally closed' rail, drilled a hole in the side of the pump housing to route the wires through and connected the whole thing up to a spare port on my air splitter. Apparently the one way valve on the air pump works to keep the pressure contained in the system while the other pump is on so that worked out great.

Just installed and tested it and it works great! According to reviews I read the batteries (2xD cells) will last 12-20 hours - BAM!


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That is awesome Matt. Something my smart electrical engineer kid could have thought of if he were interested. Awesome! Sign me up. Speaking with Kenny over my last big power outage was water quality and air. Boom! Nailed it. I am in. ;) Genius.

How does it work when the power is out?

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Originally Posted by Davidzil

How does it work when the power is out?

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Hi David,
It works via the relay, a relay monitors a signal on one side and moves a switch on the other (basically). In this case the relay (already built into a nice box) monitors the AC at the wall, there are three connections on the other side - the middle one will always be ground (or nuetral) and when power is applied to the AC side (via a plug that connects to a wall outlet) one of the other two is 'active' so if you had a circuit connected to these two it would act as the switch being switched on - the other connection acts like a closed switch.

Now remove the AC power and this all reverses, closing the open switch and opening the one that was closed.

If you put the 'normally closed' and 'ground' in place of a switch (in this case) it will act like the switch is in the off position when power is applied to the relay box, and a switch in the on position when the relay loses power.

This box can handle pretty high current too, so you could use it to do all kinds of things besides what I am showing here :)

Hope that helps.

Quote:

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Originally Posted by Jenene

That is awesome Matt. Something my smart electrical engineer kid could have thought of if he were interested. Awesome! Sign me up. Speaking with Kenny over my last big power outage was water quality and air. Boom! Nailed it. I am in. ;) Genius.

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Thanks :) You can buy one that is already built for like 12 bucks on Amazon BUT with this 8 dollar box you can do this PLUS MORE! :D ... or if you already have a battery operated pump that you like :D

Thank you Matt!

Fantastic!

Nice idea... I really this DIY project!

al