Storing cards with magnetic strips/chips (eg. credit cards) close to one another

[Wrichik Basu]

I recently bought a https://www.amazon.com/gp/product/B07X37P81D/?tag=pfamazon01-20 for storing our credit and debit cards, and similar cards with magnetic strips and/or chips. But father insists on not using it. He says that storing such cards close to one another will have adverse effects, as the two magnetic strips will help erase/destroy the information stored on each other.

I searched online, but couldn't find anything related to this. Is what father saying, correct? I don't think so, because (I believe) the strength of those magnetic strips are too low to influence each other. I mean, they are not neodymium magnets. Am I right?

 

[gleem]

I have seen posts on the internet that say it is possible if the two strips are in contact. Recommendations include having all cards face the same direction or placing the cards in a paper or tyvek sleeve when placed in a wallet. I always use a sleeve and have had no problems. Some wallets have compartments for different cards and should accomplish the same thing if only one card is in a compartment.

 

[MikeeMiracle]

The data is stored magentically on those cards, the cards themselves do not produce any magnetic forces so they cannot affect each other. A bit like storing two old style cassette tapes next to each other. The magnet is on the reader/writer to read/write the data, the actual strips/tapes themselves do not produce any magnetic fields.

Similarly with the chips too, they have no internal power source, there are wires hidden in the cards and when you bring then near a reader, the reader puts out a magnetic field which the wires pick up and induce a current in the chip, powering it and allowing it to be read. As soon as you move the card away from the reader the chip has no power again. It's the same system as door access cards at your place of work.

You can try this with old cards, the other side of the card card to where the chip is, take some scissors and cut half way through it. Your cards chip will no longer be readable as you have cut the wires which induce the current that powers the chip. You may not see the wires if you cut the card in half and try looking for them as they are very thin.

Update: On the card chips side that is used for "chip and pin" payments. Someone with the right equipment in close proximity to your cards can induce the current and then read the data the chip provides. You can get apps on your phone that can ready card data if you have NFC enabled on your phone. I have seen setups costing about £100 and a mobile phone pick up the chip details just by walking past them with dedicated NFC antenners and a suitable power source connected to their phone. If you have "chip and pin" cards there are various solutions to preventing this.

1) Get a wallet that does not allow EM radiation to pass through easily, they cost about £10
2) You can get "interference cards" which you place in your wallet like any other card. They pick up the signal and spew out gibberish data, in effect scrambling the data the cards chip sends out. Again around £10, this is what I use.
3) If you only have 2 chip cards store them next to each other, they will both respond and intefere with each others signals.

 

[gleem]

The magnet is on the reader/writer to read/write the data, the actual strips/tapes themselves do not produce any magnetic fields.

How is the strip read?

 

[sysprog]

How is the strip read?

There have been methods for unauthorized strip reading that involve adding a second reader to an ATM, or using a fake machine, but the more recently prevalent schemes use the proximity-based readability of RFID chips that are embedded into most newer cards.

 

[phinds]

The data is stored magentically on those cards, the cards themselves do not produce any magnetic forces so they cannot affect each other. A bit like storing two old style cassette tapes next to each other. The magnet is on the reader/writer to read/write the data, the actual strips/tapes themselves do not produce any magnetic fields.

Think about it. Magnetic tapes, whether audio, video, or data, are much thinner than credit cards and they are tightly wound on a spool. If there was to be any interference of the kind worried about by the OP, it would certainly happen with tapes, but it does not, for the reason MikeeMiracle stated.

 

[jtbell]

If there was to be any interference of the kind worried about by the OP, it would certainly happen with tapes, but it does not, for the reason MikeeMiracle stated.

It does (or did) happen sometimes with tapes. It's known as "print-through".

 

[phinds]

It does (or did) happen sometimes with tapes. It's known as "print-through".

Only, I think, if you store them in a warm place and in any case you're still not going to get that with credit cards. At NASA we had data tapes that kept their data reliable for decades (but they WERE stored in a cool room).

 

[jedishrfu]

I agree with others here. Magstrip technology has been around a long time in computer tapes, video recordings, audio recording reels, casette tapes...

The strip surfaces while close are separated by a thin strip of mylar with no degradation over a few years time ie upto 5 yrs at least. When they do degrade error correction for digital and signal fading for analog happen but they still work well enough to use and to copy.

The charge cards have even greater distances between them. Any loss of data is more likely due to magnets or scratching of the surface. For audio and video tapes sometimes the write head would interfere ruining the recording or either read/write head got out of alignment through misuse or overuse and read failures would occur due to tracking failures.