And now for something completely different - garage doors

After our installed-last-July electric garage doors kept failing and being "fixed" by the installers, they got the manufacturer out to take a look. He diagnosed low batteries in the remote device attached to each door which detects obstacles as the door is closing (roller door). (thus avoiding the scenario in that commercial that shows the kid using the garage door remote instead of the TV remote and bashing his Dad's car's roof 50 times).
Failed again today after less than two months of the "new" AA batteries. So I replaced these "new" batteries (BB: 01/2021) with a couple of unused Pannies that were kicking around (BB: 06/2012) which were still both over 1.5V. The replaced ones show 0.5V and 0.9V respectively. Hope these last a bit longer.
The device on the door is smaller than a TV remote and should be taking next to no power. But if the door controller can't contact it then it won't move the door, just beeps instead.

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Maybe I've misread the above. But what I'm getting from this is that the installers were called out a couple of times which then led to manufacturer's guy being called out who then diagnosed that the only problem all along was flat batteries in the remote device.
Again maybe I'm missing something here, but for me anyway any fault diagnosis always starts with the things which are easiest to check. And given that presumably instructions came with this explaining how to change the batteries when they ran down as they inevitably would, why you never thought of checking them yourself. The fact that the installers didn't think to do this either is astonishing;although had they been charging for their time that might have been different.
As to the batteries, sell by dates etc, I buy strips of cheapos from the pound shop which if necessary are checked using my tronic tester from Lidl which I find are perfectly adequate for testing purposes.
michael adams
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Why on earth do they use batteries? The door must surely have mains power and it surely must be possible to put the detection device on the 'other member' (i.e. wall/floor).
Our doors simply have a setting that reverses the door when it meets resistance, you set it so it can just close the door without reversing and then any extra resistance stops it.

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You mean where I'll drive over it or trip over it? I suppose it could be buried and a cable run to it but that would mean messing with the concrete floor. Hardly a selling point.
This is a roller door, could they reliably get power to a point in the middle at the bottom of the door?
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What sort of door and where/what is the resistance detector?

On 01/04/16 12:16, Tim Streater wrote:
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And it would not help prevent the doors bashing into a car/person/etc.
I suspect the reason for batteries is the relative difficulty in running a cable along a rolling shutter door - though I would have thought they could have been a little more creative - I can think of at least 2 ways to do that:
1) Let the cable roll up with the door - would need careful design of the shutter and probably not that easy;
2) Cable dangles down to bottom edge of door and is kep out of the way by either a bungee to lift it up as the door lifts, or a sprung cable reel so the cable rolls up as the door is opened.
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Tim Watts wrote:
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If I was going to place a sensor there, the sprung cable reel seems like a good bet. The extra space required might be inconvenient, though.
I'd like to know what this detector detects and how reliable (in terms of false positives and false negatives) it is.
My large double up-and-over garage door uses a simple resistance-to-motion detector, which is surprisingly sensitive and completely trouble-free. FWIW it's been stopped by car bonnets without leaving the slightest mark, and I've never had any compunction about stopping the door with my hand.

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Yes, that's what I was trying to describe above.

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The installers last year may well have explained that I needed to change the batteries every year or so. The doors, however, are under warranty and since on the first occasion or two there was no beeping (which indicates that the batteries may be low) I was not about to mess around with them. They may well have changed the batteries.
The manufacturer's guy was more forthcoming with explanations; and even he said they should last about a year. Given that the batteries he put in have gone flat in six weeks or so either they're using a source of crap batteries or there's some other, undiagnosed, fault which is causing a high current drain. If these batts run down fast then I shall measure the current usage.

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The most plausible explanation, giving your mention of TV remotes is that maybe these things are active and thus draining the batteries when they're supposed to be switched off. Whereas TV remotes are only active when somebody presses a button. Do they contain a motion sensor of some kind which isn't switching them off once the doors are stationary?
Otherwise if they're active all the time then the correct type of battery* would need to have been fitted. Although the installers should already have known this, just as they should have tested the batteries before they installed them; as pocket testers are only a few quid.
michael adams
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* As explained on sites such as Battery University.

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That's a good question. The control unit will be communicating wirelessly with the device on the door, but given these are less than 10 feet apart the power required should be minimal. If it continues to eat batteries, I can rig something up to measure power consumption statically and as the door moves up and down. I haven't looked closely at the innards of the device yet.
The door, being roller, is made from slats that are mebbe 4 inches wide. These are all hooked together, with no gaps between them when the door is closed. As it opens, small gaps open up as it rolls up and onto the drum. So, when closing, the bottom slat (with the sensor device), reaches the ground and stops. At this point there's still six inches or so of unwinding to do at the drum. The installers did a good job here; the gaps disappear just as the drum runs out of door.
This was actually a car-port, originally, but we were burgled last year and having doors added removes a clue for scroats as to whether there's anyone at home. The whole thing is mechanically much better than the garage door I had when in the US. We'll see whether the electronics is more delicate.

Are you on holiday abroad at the moment, or attending a convention in some exotic clime ?
As your posts are timed 1 hour earlier than GMT + 1 or whatever it is ATM in the UK. That's in Opera as well IE BTW
michael adams
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Make that 1 hour later.

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I just restarted Thoth, any better?

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Not until the end of April when we will be in Venice.
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Hmmm, odd, this Mini gets its time from time.euro.apple.com, is showing the right time and Time zone is set as BST. Possibly I need to restart Thoth.

On 01/04/2016 14:30, Tim Streater wrote:
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ISTR your posts having this problem in previous years.

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According to Francesco da Mosto the best time to see the place is before 6.a.m. when the tourists start getting up, and wandering about.
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Although it's never a good idea to make assumptions about what other people can see on the screen in front of them, unless you're a scammer anyway, I'd imagine your posts should be appearing out of synch in the threads as they appear in your newsreader. People are seen as replying to your posts before you've even sent them.
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I couldn't possibly comment.
michael adams
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On 01/04/2016 00:06, Tim Streater wrote:
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Might be worth checking the actual power consumption. Its not unknown for something like that to slip though the testing phase with a dodgy surface mount ceramic cap that is acting as a partial short and draining batts faster than it should.