Help needed to lift internal electronic bifold door blinds - Page 1
Forum section: electronics / beginners

author: AirborneSnail
author_rank: Newbie
timestamp: September 08, 2025, 08:00:09 pm
content: My bifolds have 'Sunbell' internal electric blinds (never again) with no manual override. They use a 'master' controller and a 'slave' unit that magnetically attaches to the glass of each door. The blinds have been halfway down for years, I now want to lift them all the way and leave them there. So a one-time lift on each pane of glass (5 in all). The rechargible battery in the controller no longer holds charge so I need a new one. I contacted the supplier and guess what, they no longer supply that system, it's been upgraded, so one new master and slave would cost me £350!!! -for a one time lift. There is a bonafide battery supplier in italy but they don't/can't ship to the uk. The battery is an L-shaped 11.1v 700mAh 2pin JST-PH connector. I was thinking of maybe using a drone battery with the same power, wiring it into the slave unit (the master uses AAA batteries) and using that to lift the blinds. But then that'll probably need it's own new charger. Does anyone know a clever and cheap way to overcome this issue? Many thanks

author: themadhippy
author_rank: Super Contributor
timestamp: September 08, 2025, 08:11:20 pm
content: rip the batterys out and hook it up to a bench psu

author: Analog Kid
author_rank: Super Contributor
timestamp: September 08, 2025, 08:12:33 pm
content: [possibly dumb] guess: how 'bout just a fixed DC power supply temporarily wired in lieu of a battery?You did say it was just for one time ...

author: AirborneSnail
author_rank: Newbie
timestamp: September 08, 2025, 08:13:54 pm
content: I've never done electronics before so I don't know what a psu is. Whatever it is though, the slave needs to still be able to stay on the window for operation. I tried removing the battery and running the controller whilst attached to the mains through it's specific charging adapter, but this didn't work

author: Analog Kid
author_rank: Super Contributor
timestamp: September 08, 2025, 08:19:39 pm
content: Some confusion here as to what you actually need to fix this:Do you need to power both the master and slave? Both temporarily to lift the blinds, then you can un-power them both?A PSU is just a DC power supply. Something you can easily obtain online, like a small "wall wart" power supply that plugs into the wall and gives you the proper voltage (say, 12 volts for your 11.1 volt battery, close enough). You would just need to do some simple wiring, perhaps a bit of soldering, but that's about it.

author: AirborneSnail
author_rank: Newbie
timestamp: September 08, 2025, 08:29:08 pm
content: Yes, power to both the master and slave. The master takes a AAA battery, simple. The slave takes the specialist battery.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 08, 2025, 08:42:41 pm
content: Then you *should* be able to connect a 12 volt power supply to where the battery connects and power the slave.Does that make sense to you? Just get a 12-volt DC supply, connect it (make sure the polarity is correct! plus to plus, minus to minus), then do what you need to do to raise the blinds.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 08, 2025, 08:56:19 pm
content: One more question, since it's still not clear:Does the slave only need to be powered just the one time to raise the blinds?Or does it need to be powered all the time to keep the blinds raised?

author: AirborneSnail
author_rank: Newbie
timestamp: September 09, 2025, 06:00:16 am
content: In answer,Analog Kid, and for anyone else finding themselves in the same position, it only needed to be powered once to raise the blinds and then they stay up on their own. My brother came up with a cheeky idea which worked. I disconnected the rechargable battery from the controller. Using the same JST connector, I wired a 9v battery taken from our ceiling fire alarm, directly into the handset. Placed it onto the magnets on the window and hey-presto, the blinds all rolled up! (one at a time). It wasn't even slow either. I thought using only a 9V they'd crawl up. I'm super relieved as I can now actually see out into the garden & I'm not using the blinds again. This was very much a bodge, but it did work. And it saved me waiting weeks for a new master & slave to arrive, and, shelling out a painful & unnecessary £350+VAT. Many thanks to everyone who replied to help me.Incidentally, my brother thinks it's the controller charger that's broken & not that the rechargable batteries can't hold power any more. He said it's very common for this type of charger to break and that 'the capacitors inside are cheap rubbish & break easily'. I pointed out that the rechargable controllers hadn't been used for nearly 10yrs so I thought they'd lost their ability to hold charge. He said that at least one out of 5 would still be working, (each pane of glass has it's own) not all 5 dead. So I might try and get/borrow a cheap replacement charger and test his theory out. I'd be interested to hear others opinions on this type of charger/adapter. The little plug on it is too small I think to try and test with a multimeter. Pics attached of the solution that worked for me.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 09, 2025, 06:42:13 am
content: Hey, I like those blobs of, what is it? modeling clay? on the battery terminals.Congrats on getting it fixed.

author: AirborneSnail
author_rank: Newbie
timestamp: September 10, 2025, 07:50:29 pm
content: Blobs are good old British Blutac.

author: Analog Kid
author_rank: Super Contributor
timestamp: September 11, 2025, 12:33:12 am
content: So the "master" in this case is really a remote, innit?