Self Bondage Time Locks

All the time locks I've looked at (Amazon, Extreme Restraints, etc.) are either ice locks or rechargable battery locks that fail in the locked condition (or unlocked if not locked) when the battery is depleted.

Ice locks don't trip my trigger despite the failsafe design. After the ice melts, the lock is open.

Is there a battery operated (changeable batteries or usb-charged batteries) time lock that fails open when battery dies?

The closest you can get is a electromagnet. They work until the power source is cut off. So if you use a timer along with a battery as a power source you have a fail safe system. If the timer fails the mag lock will release when the battery dies. The strength of the mag lock can be from 30lb and up to 1200LB. Online they say you can get a 1200LB 12v version for about $30. Not to many people can bench press 1200Lb and if you deploy it such that the magnet has a mechanical advantage they are going to have to be a Marvel Hero to get released.

One can design a box big enough to hold a suitable size battery, I would use something like a gel cell of at least 12VDC and 7AH rating with a charger. Now a 1200 lbs. electromagnet is a bit of an overkill and draws almost 1 Amp to keep it energized. Now if you design the cabinet that one can not open easily to withstand 80 lbs. direct pull then I would suggest this, https://cdn.adiglobaldistribution.us/adina/Upload_SL-E941SA80Q_ProductManual.pdf as this one only needs 85mA @ 12VDC. Have you found a suitable timer mechanism?

For a timer you can use a relay in the circuit that is normally open. That way if the control circuit fails it opens and the Magnet is released. If you use a ac transformer to power just the relay (not the electromagnetic) you can use any timer or smart plug to turn it on or off. With the smart plug you can hand off control to someone else to remotely decide when you get to get free. voice command also become a option for release which opens many options.

Just to point out something, The battery charger should not be used during play. A batteries limited capacity is what give the setup a fail safe.

A 7.5 Amp Hour battery can keep it locked for 7.5 hours which to me would be pushing max time limits. At 85 Milliamps the math works out to 88 hours. which would be well beyond a safe time duration if something went wrong. 88 hours is 3.67 days and our friend Google say you can live for 3 days without water. I would not want to be the person trying to confirm if Google got it right or not.

Very very dangerous. If there is a fire or other emergency you need to be able to be released before the time is up. This is risking your life. At least have someone that knows you're restrained around in case of emergency. Also if there is some kind of unforseen electronic failure your in trouble, again why you really need someone else for safty. Machines have no concions so don't care if you die.