Can anyone tell me any adverse effects of disconnecting the battery for short periods of say 1hr to 12 hrs. There is a battery cut-off that can be used as a simple anti-theft. To install, you disconnect the ground terminal from the battery and connect this device to the battery post, the re-connect the ground strap terminal to the device. There is a large **** on top of the device which, when removed (and put in your pocket), cuts off the (-), so no power. Easy enough to fool, if you have the right size bolt I would imagine you could just screw that in and complete the circuit.
Also helps if your spare consists of a cell phone and CAA (or in the States AAA) card.
Friend of my uses it on his TR4A but obviously no electronics to mess up.

 

Won't hurt the car, but it'll be a PITA to reprogram your radio and reset your clock every time you get into your car.

 

Al,
Shouldn't cause a problem, with a little thought you can easily wire in a small rechargable battery into the system that would keep the clock and radio memories alive. But it would be able to supply "ignition on" curents if someone tried to tamper.

The battery would be trickle charged once the main battery was reconnected.

 

ooops sorry, that should of course read "...would NOT be able to...."

 

There are probably better ways to disable the car for anti-theft purposes. I like the idea of disabling the fuel pump. That way, in a car-jacking situation, they can drive it away but not get very far.
Here is the ground disconnect switch in my '78. Very handy for service.
<img src="http://www.flash.net/~ego/gndisc2.jpg" alt=" - " />
The '87 ground strap is under the tool panel and easier to disconnect.

 

They make a disconnect with a small bypass wire w/ a diode (I think) that allows enough current to keep you presets up but not enough juice to start the car. Its the one w/ the green **** on top. Sorry I can't remember more.