Compasses and batteries?

[crofter]

We all know that if you put a battery close to a compass it will affect the compass needle. Because of this, or because of something I may have read in the past - I have always been paranoid about storing my compasses near anything metallic or magnetic, or batteries in case it permanently affects the accuracy of the compass.
For example: I have never carryied my silva in the same rucksack pocket as my headtorch. I never feel happy to pack a survival kit with compass and batteries for the same reason.

Does anyone else do the same?
Does anyone know if there is any substance to this fear or should I not worry and pack em how I like??
Ade

[Adi007]

I don't think that there is any real danger to a compass unless it is put into close proximity to a very strong magnetic field or an oscillating magnetic field.

That said it's also not a bad idea to store a compass so that the needle is free to move but having said that I don't bother and I've got a Silva Tyoe 54 that seen years of use and is still accurate.

[arctic hobo]

I'd pack it how you like if I were you.

[alick]

Batteries do affect compass needles but only if they have a case made from ferrous metal. Like some or all of the leak proof ones.

The battery can't affect the compass just because it's a battery. A battery stores energy in a chemical form which doesn't have any magnetic effect until you put it in something and turn it on, only when an electric current is flowing does it make a weak magnetic field around the wires it flows through.

But a piece of metal that will affect a compass needle shouldn't do any harm. Remember that powerful magnets are supplied with a "keeper" bar of plain steel that you put between the two poles when the magnet isn't in use. That concentrates the magnetic field into the bar and is supposed to extend the useful life of the magnet, not harm it.

I don't think you've anything to worry about. It needs an alternating current (like mains, not a battery) to have a demagnetising effect on a needle.

Cheers

[crofter]

Thanks everyone for the advice. I'll pack them all together from now on.
Ade