Well, they finally turned up. I won't open one up, since redsonic already did, and covered that off pretty well.
So first, actual measurements:
- Body size: width: 46.2mm; height: 43.3mm; thickness: 18.4mm; height including (locked) shackle: 78.5mm
- Shackle thickness: 5mm
- Shackle internal dimensions: width: 30mm; height (locked): 30mm
That's slightly taller - 6.1mm - than the old style locks, but the width and depth are pretty close. The new lock is considerably heavier than the old style - 110g vs 30g for the old. The lock body surface is metal (looks like aluminium) but may be just a layer on the outside. (That's not clear on redsonic's pics - the internal pics show a black body, while his external pic shows a silver body, so I'm not sure if if that's two different locks, or if something else is going on.)
The thicker 5mm shackle will restrict what you can use it for - a lot of the locking buckles I have around here are too small (and some of those have already been drilled out to accommodate the 4mm shackle of the older style lock).
Specifications regarding strength are the same as for the old style lock, although the new one certainly looks stronger.
The power input is a micro-USB. The "reset hole" shown on the images in the AliExpress link I originally quoted is, as I suspected, not there - the USB hole is in about that location. It doesn't come with a power supply, but does come with a 50cm USB charging cable.
Controls: the "user interface" is practically identical to the old style lock: three buttons, marked "H" and "M" (for hours and minutes) either side of a central "lock" button. The H & M buttons set the timer, adding one hour or minute per press, wrapping to zero after 99 hours or 59 minutes respectively, and do basically nothing once the timer is started (apart from lighting the display backlight, which goes off again after 5 seconds). Once set, you can start the timer with the central "Lock" button; the thing will beep once a second for five seconds, then the display "lock" icon will show as locked, and the display shows the remaining time.
Unlike the old style, there's just a long beep (if the buzzer hasn't been turned off) when the lock is "locked" (i.e. the timer is engaged and the countdown reaches zero) - there's no mechanical sound. The mechanism only unlocks; this happens automatically when the timer runs down, but if there's any reason to unlock it at a different time, e.g. if you've closed the shackle without the timer running, or if it was jammed when it previously attempted to unlock, you can trigger an unlock by pressing the middle "lock" button (several times, see below). If you operate the mechanism with the shackle open, you can see the catch retract and return, accompanied by the sound of the motor.
As expected, the lock icon shows locked when the timer is running, regardless of the physical position of the shackle, and unlocked if the timer is not running (and the unlock can be triggered by pressing the "lock" button). You can close the shackle after the timer has started, and it will lock and stay locked until the timer completes, or you can close it before starting the timer. The lock doesn't "know" if it's latched or not.
You can start the timers on several locks so they will all unlock at about the same time, then take your time in applying them ... and you don't have to fiddle with the buttons to do so (potentially adding an hour if you accidentally press the wrong button - I did that once with one of the old ones).
Note that for the lock button to unlock it, the timer must be zeroed. If you press it with anything other than 00:00 showing on the timer display, the 5 second countdown will start, and you will need to press the lock button again to reset it (which will zero the timer). An additional press will then trigger the unlock. If the lock has gone to sleep with a timer still set (and that includes remembering it from last time), you'll need to press the "lock" button several times to unlock it: the first press will wake it up, the second will re-display the previous time, the third will start the countdown, the fourth (assuming you get it in before the countdown finishes!) will reset the timer, and only the fifth will actually unlock it. So if you find yourself needing to unlock it when it's latched (but with no timer running), just press the "lock" button repeatedly at around one second intervals until you get the desired result.
I'd suggest resetting them after use by pressing the "lock" button as many times as needed to zero the timer, and closing the shackle after use. That way you need to unlock it before the next use, and should have an idea whether the battery is OK and the lock is operable.
Holding the middle button down for three seconds toggles the sound on or off (again like the old style). I note that the beeper is a lot more polite than the old style locks, which was irritatingly loud.
There is an "emergency reset" feature. When locked, if you hold the H and M buttons down together for ten seconds, the lock will unlock and reset. You can do this three times, after which the "feature" becomes unavailable. I suspect most folk will want to disable this - do that by setting a short time, locking it, then holding the H & M buttons down for ten seconds, until it resets, repeating that procedure three times.
I'm not sure if "hard resetting" it (by shorting the reset pad, or if the battery goes flat) turns this "feature" back on.
The lock seems to unlock even if the shackle is under some strain. but it's not hard to put enough force on it (pulling the shackle outward from the lock body) that the latch jams and doesn't release. If that happens, you can use the middle button to release it once you've got the strain off it.
It's pretty easy to shim the thing open - I used a piece of plastic cut from the packing it came in (stiff, but thin), but you could use plastic from a drink bottle or cut a piece out of an aluminium soda can. You just wrap the cut piece around the outside of the shackle, slide it into the lock as far as it'll go, then rotate it around to the inside of the shackle, pushing the latch out of the way as it goes. It's easy enough to do that I'd be doing that before peeling the display cover off and dismantling the lock, which was the easiest way into the old style locks.
(Other options, as noted above, include brute force and portable EMP generators...)
That does mean that if you use it to lock someone out of something (as opposed to locking them in), it's pretty easy to undetectably and non-destructively unlock it (and potentially re-lock it) with minimal tools. By comparison, the older lock needed you to at least peel the cover off the lock display. Tighter tolerances between the shackle and the hole it slots into would help here. You could also make a shroud that would prevent that attack, but that would be a bit of a pain.
In summary, compared to the old style locks:
- Pros:
- the whole thing feels a lot more solid;
- it's a little more flexible in how you can use it;
- the lock opens automatically so you don't need to fiddle with the unlock button; and
- the sound is much more polite.
- Cons:
- the thicker shackle will reduce its usefulness;
- it retains many of the quirks of the old style's user-interface; and
- It's a bit too easy to shim open undetectably.
Basically, it's just generally nicer than the old style plastic timer locks, but it won't fully replace them.