Looking for high-capacity AA rechargeable battery

Can you not wire the sensor up from the door opener? Most have low voltage output, you just need a cheap buck convertor type device, to give 1.5v or 3.v)

You need to trickle charge the battery from a permanent supply. Similar to most safety systems.

The sensor is attached to the door. So I'd need some kind of flying lead or coiled cable.

Not tried them, but they look like a lithium ion cell with an integrated

They say "low self-discharge of 1%" but that's 1% per day/week/month/year?

Do you know if your door has a high load, or it doesn't like the voltage curve of the batteries you're fitting? eg a NiMH starts at 1.55v but falls rapidly to 1.2v where it stays for a long time. The device may decide to shut down for low battery at 1.2v, even though the cell has a long life left.

Another option is an LFP (lithium iron phosphate) cell, whose voltage curve is 3.5v when fully charged, nominal 3.2v, empty at about 2.5v. That's roughly the right ballpark for 2xAA and might be better for things which are grumpy about voltage. You can get LiFePO4 AA cells which you could use with a dummy cell, but they aren't very capacious in that form factor - better would be an external (protected) LFP cell and a couple of dummy cells with flying leads in the sensor.

Theo

It cannot be a well designed safety system if it discharges high capacity Extreme Lithium batteries in a month, and relies on these batteries.

It needs 5V to charge! BigClive explains

The safety sensor must be drawing current all the time.

Can the safety sensor be replaced with a less-consuming version ?

The thing is, a zillion other people must have this problem. What have they concluded ?

I would not "leap to a conclusion" without a characterization first. A different battery, does not remove the knowledge that the stupid thing needs continuous maintenance. Sure, you could select batteries much bigger than the cabinet on the sensor and put them outside the plastic enclosure. At some point, with a big enough battery, only the "self-discharge rate" of the battery affects success.

Paul

When the 2 x AA combined voltage is too low, you can open but not close the door. When I check the two batteries' voltages, they might then be 0.7 and

It is. I did measure it but forget what the draw is, but it's a lot more than the 2mA that they claim.

Perhaps, but not by me. It communicates wirelessly with the door control unit.

A bigger capacity battery that I would wire in and recharge offline would be favourite, if it lasted a few months.

Ah, that explains how they are able to boast that those batteries can supply a constant 1.5V up until the moment that they can't -> zero.

I think they'd have gone flat in my application well before the self-discharge became a problem. If I tried these, they'd either be on-charge or in-service.

The batts I'm using at the moment, Eniergizer Extreme Lithium, are around 1.6V new. When I remove them from service (because the door control box is beeping), the combined voltage of the two is usually not much more than 1.3V or so.

That's worth looking into - thanks. My recollection of the sensor unit is that it would be easy to wire it to an external battery that sits next to it at the bottom of the door.

Are you sure the door sensor isn't faulty? I have roller doors, albeit ancient ones, and there is an IR beam across each door with a reflector on the far side - the door won't close if the beam is interrupted. Because the IR source/detector is on the frame it can be powered from the controller.

My suspicion is, the controller expects to see a radio status report at a regular interval. An absence of radio signal, would be an excuse to not close the door.

If it were not for that, you could do a sensor where the controller sends an RFID pulse to "activate" the sensor, and the sensor only transmits long enough for the door close to finish.

You should be able to make a scheme, with much better behavior than what this thing seems to be doing. Continuous radio operation would be fine for something that was line powered.

If the consumption really is 2mA, you could likely cook up an optical power source for the thing, whether the garage is dark inside, or is lit by sunlight. An IR source located in the garage, could transmit enough energy to keep the sensor running. A photocell array and a regulator. Running off IR light (for a less-obvious-to-visitors kind of solution).

"wavelengths from approximately 400 to 1100 nanometers"

In what follows, my assumption is that good items will not be an exact match for the job.

IR LEDs can be purchased, which emit at 850nm (dull glow) or

The only reason for buying something this big, is so that it does a good job on relatively low light sources. An inefficient 3V linear regulator being the intended circuit connected to it. Linear regulators are relatively easy to wire up, and they can accept a peak input of 35V. And the PV panel, being 12V, likely does not reach 35V open circuit and no load. I'd buy a lower voltage one, like 6V or 9V, if I could find one. Allow 3V headroom for a 3V regulator, so then it will not matter what linear regulator you buy. A 6V panel minimum output, should be enough. When fully illuminated, it may produce more voltage.

I've made LED arrays before, for illumination, and drilling the holes for that will drive you nuts :-)

This one is a wide angle source. If the LEDs have a mini-lens on each one, the result is a "circle of light" where it lands. The circle can be 15 degrees or so, too tight. Some of the LED types have a flat face, which is better for wide illumination. You could put a piece of tape over the night sensor, so it runs all the time.

The illuminators do not seem to have intensity controls. If you were doing your own source, you would use PWM to adjust the output power and reduce the power consumption as desired.

To review the output pattern of the emitter, you can check it using the camera on your smartphone. This is how B&E specialists check your premises for surveillance equipment. Look for IR emissions using a smartphone.

Paul

Even 2mA will drain a battery fairly quickly - 1000 hours or so

That is only a couple of months or three.

You could if there is space get a big RC style battery and a 5V converter. In general a LIPO is 3.5-4.2v over its discharge cycle. You probably want a single LIPO cell of around 10Ah.

I don't know what the idle draw on such a convetrer is, though.

Tim Streater snipped-for-privacy@streater.me.uk> wrote in news: snipped-for-privacy@mid.individual.net:

I had a similar application, long standby and light/moderate current. Bought a set of those below, tested them a bit but haven't made full use of them. 10months later they're still showing 1.5V so I don't think you'll have a problem with self discharge.

I did a lot of research on claimed capacity vs actual and found the AmpTorrent brand to be pretty good and tested them to full clained capacity of 3000mAh on arrival, recommended. Cheaper than your Hixons too so I'd say worth a punt (£23.98):

The door is in one of four states:

The current draw in these four states is:

From this I deduce that the only state the sensor is really used for is (4), perhaps unsurprisingly. I think that as the control box is told to close the door, the sensor is sent an order to start monitoring for obstacles to complete and safe closure, such as some kid's head or arm. When the control box knows the door is closed, it tells the monitoring device to leave off.

Now, I can't see why it would need to be drawing 12mA to sit there and twiddle its thumbs. In fact, if I were designing it, I'd make it listen for 0.25 secs every 2 seconds for a start command, thus allowing it to be really drawing next to nothing for 7/8ths of the time. The control box, at door closure, could send the "start monitoring" message for several seconds until the sensor replies. Once it starts replying, it's then replying continuously until told to stop, hence the 30mA draw in that phase.

But wouldn't the wireless technology be much the same as, say, a wireless thermostat that can operate a year on a couple of AA batteries.

That's the problem with converting the voltage, is whether the converter has any magic sauce for avoiding excessive quiescent load.

Some conversion devices we use in everyday life, they "cut off" at low load. This creates a nuisance for devices expecting steady power (even at almost no load). Some inverters operating off leisure batteries, may do that, to avoid running the battery flat.

The UPS for my computer does that. If operating on battery, and the drain drops below 10-15W, the UPS stops putting modified-step AC on the output. The assumption by the manufacturer is, the power provided is there just to make a clean shutdown for the OS on a computer. Once the current drops, that is evidence it has stopped (one way or another).

Maybe you could arrange a converter to run in putt-putt mode, bang-bang control to operate the converter to keep the voltage within certain bounds on a capacitor. If the actual drain is zero (battery out of device), maybe the converter can stay off for long periods of time (output capacitor leakage).

Paul

Those actually so nothing 99% of the time, They wake up occasionally and send a burst of radio traffic, then go back to sleep.

If it's 1% a day, that's 30% a month. Sounds like you would be swapping them more often than that.

Sounds like it's running them into the ground, rather than giving up early. So the issue is capacity not voltage.

A bit overkill for your purposes, but:

Theo

Well, if you think it's working as designed and you don't fancy replacing it with an IR beam across the doorway, then howsabout using rechargeable batteries that are charged via a couple of contacts which allow a charging current to pass from the frame to the device when the door is in the closed position (and in the open position as well, if you tend to leave it open) ...