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Hard wire a Sureflap cat flap with battery backup? (self.offtopic)

submitted 11 months ago by sylverstream to c/offtopic

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I've got a Sureflap cat flap operated by 4 AA batteries. It doesn't work well on rechargeables, it seems to need 1.5v batteries.

I'm thinking to hardwire it with battery backup (like a Ups). I'm not very experienced in electronics, are there any off the shelf products I could use? I'm assuming the flap runs at 6v and that I can just attach two cables, one to plus, one to min.

If there are no off the shelve products, any recommendations for what I should buy?

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[–] InEnduringGrowStrong@sh.itjust.works 4 points 11 months ago (1 children)

Check whether the batteries are all in series, if so then that's 6V. I'd match the voltage to keep things as is.
Might wanna confirm with a multimeter, the cheapest one works for what you need here.
That would allow you to also confirm the current (amps) required when it's idling and when it's operating the flap.
Which then also allows you to calculate how long whatever battery backup would last.
TL;DR: Power supply voltage should match, available amps can be higher or equal.

Then you can just search digikey or whatever electronics retailer you have and order a battery pack for said voltage... which, for 6V, would really just be 5 cells in a wrap.

Alternatively, you might get away with just cramming an extra rechargeable AA in there yourself (5x1.2V=6).

Make sure you don't hardwire a power supply while there's alcaline non-rechargeable batteries in there.

Technically, instead of putting the battery backup in the device it could be on the other end of the hardwire you're takking about doing.
Hell, if you already have a UPS for something else nearby, you could just plug a 6v dc power supply in that.
There's a few ways to go about this.

[–] sylverstream 2 points 11 months ago (1 children)

Interesting, hadn't thought to keep the batteries in the device. It currently works okayish on 4 rechargeable but not ideal. Not sure how to cram the 5th one.

Was thinking to put the battery backup outside.

I see usb powered aa battery replacements on Aliexpress for cheap. With an ups with usb out I should be covered :)

[–] InEnduringGrowStrong@sh.itjust.works 2 points 11 months ago (1 children)

USB is gonna be 5V, which is lower than 6V, but then if it kinda works on 4x rechargeable, that's probably 4.8V fully charged depending on battery chemistry.

UPS and USB might work.
No clue how much amps that motor pulls when activated, so it's hard to give you a minimum for amps.

[–] sylverstream 2 points 11 months ago* (last edited 11 months ago) (1 children)

I was thinking this usb powered battery replacement which has a 6v option. https://a.aliexpress.com/_m030556

There's no motor, just a click system to unlock / lock the flap. And easiest would be to plug it into a power bank which is also charged at the same time by 220v.

[–] InEnduringGrowStrong@sh.itjust.works 2 points 11 months ago

Right so just an actuator which probably doesn't need much current