12V DC Electromagnetic Locks

[lesabret]

Anyone have any experience with the types of electromagnetic locks that are used to secure doors? I'm looking for one in the small-medium range. Don't need 1200 lb. of resisting force. Just something to secure a hatch cover that would be stronger than a simple keyed cam-type lock.
Here's a link to Amazon just to show the kind of thing I'm talking about. Just an example to demonstrate the concept.
There are many out there advertised and never having used one before, I don't know how fussy to be about the supplier. Thanks for any guidance.

Dave

 

[toyotech]

Does it need 12v to keep it magnetic or does it work the other way around? I like these


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[dwh]

Does it need 12v to keep it magnetic or does it work the other way around? I like these

Depends. You can get them either way, but most release when the power is cut. Pretty common on large modern apartment buildings to hold open fire doors - when the alarm goes off, it cuts power to the magnet that is holding the door open, and the automatic door closer pushes the door closed.


https://www.google.com/search?q=fir......1ac.1.34.heirloom-serp..59.0.0.Z2NMFXe2sL4

 

[dwh]

There are other ways to go. There are electromagnetic locks that have a pin that retracts when power is applied:

https://www.robotics.org.za/index.php?route=product/product&product_id=582


And of course, the ol', "Buzz me in":

https://www.google.com/search?clien...&ie=utf-8&oe=utf-8&channel=suggest&gws_rd=ssl

 

[toyotech]

I figure if it needs 12v to stay locked... Battery reserve might be an issue


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[dwh]

I figure if it needs 12v to stay locked... Battery reserve might be an issue

Yea it would; even .15a adds up 24/7/365.

 

[lesabret]

Found an Electromafnetic Cabinet Lock

Thanks for the replies. I came across this while traveling down the intarweb rabbithole. 250 mA @12V. If my math is correct, then about 4 hrs. for every Amp-Hour the battery(s) can provide, No?
My idea wouldn't include having it locked 24/7. It would only be when I feel it necessary. Probably only for 6-8 hrs. at a time. Battery system ought to be able to handle it and recharge in between.

edit: Whoops; fat fingered the post title. I think you guys know what I meant. Hey, maybe there is such a phenomena as electromafnetic.

 

[dwh]

Thanks for the replies. I came across this while traveling down the intarweb rabbithole. 250 mA @12V. If my math is correct, then about 4 hrs. for every Amp-Hour the battery(s) can provide, No?

Depends on how you rig it - that unit in the link can be rigged two ways. The unit in the link is a pin lock, not a magnetic lock like in your first link.

The small part (the strike) slides into the lock, and the pin pokes through it. The bigger lock part has an electromagnetic solenoid, which pulls the pin back to release the strike.

You can rig the solenoid so that it takes constant power to keep the pin in the strike, so that when power is lost, it unlocks. That's called "fail safe".

Or, you can rig the solenoid so that the pin stays in the strike on its own, and it takes power to pull the pin back, so when power it lost, it stays locked. That's called "fail secure".

So, if you rigged it "fail secure", then it'll stay locked until you hit the switch to apply power. In that configuration, it wouldn't use any power until you want to unlock it.


That's a nifty little lock.

 

[jeffjeeptj]

Looks like a neat lock. I do suggest a redundant way to open if the solenoid fails.
My son had a 911 Porsche with the vehicle battery in the front compartment (trunk). He had it parked at the airport while away on business. Newer 911s have an electromagnetic trunk release and that car had no manual override. So when the battery failed at the airport, no access to the battery. Choices when returning at 11:00 PM were taxi and deal with it later, tow truck, little battery with pigtail inserted in cig lighter with key turned on (which did not work), or call wife and get two kids up at late night. Some choices are better than others. This obviously is not a solenoid failure, but ...

 

[rayra]

Just a cautionary word to the OP, be aware that a lot of jurisdictions in the USA have criminalized hidden compartments. Not saying that's what you are doing or that it's even wrong. So anybody that thinks a remotely operated lock would be really useful for such a thing should factor that in to your planning.