One wallet on multiple devices

Bitcoin Questions and AnswersCategory: General questionsOne wallet on multiple devices
Dirk Thomas asked 2 weeks ago

Hi,

I have a Mycelium wallet on my iPhone für daily expenses. Can I use the seed phrase to dublicate the wallet onto another mobile device and use both devices alternatively? (= Can I spend the very same Bitcoins with either one of my devices or should I have two different wallets with different Bitcoins on each of them?)

I ask this, because I don‘t really understand the technology and wonder, if my iPhone-wallet is the actual location of my Bitcoins (like cash in a pocket) or only the interface to my digital funds somewhere on the internet (like an online-banking tool).

Thanks a lot vor your help!

Dirk

1 Answers
Steven Hay answered 2 weeks ago

Hey Dirk,
 
While it’s technically possible to do this, by exporting your Mycelium private key as a seed phrase or QR code and importing it into the wallet on the other device, I wouldn’t advise it.
 
I think doing this will likely result in problems. For example, change addresses are likely to cause difficulties. If you have 1 BTC (which came from a single payment to you) on wallet A and make a payment of 0.5 BTC, how Bitcoin works is that it’ll send the full 1 BTC but split it between your recipient’s address and a new change address controlled by your private key. What I can see happening is that, after this payment is made, wallet B won’t be aware of this new change address and will display a 0 balance, whereas wallet A will display the correct 0.5 balance.
 
In short, I think doing things this way is likely to lead to all sorts of unexpected behaviours. Unless you can find a wallet specifically designed for syncing between multiple devices, I’d say that it’s better to create 2 separate wallets. To avoid transaction times and fees, it should be possible to sweep bitcoins between these wallets if this functionality is supported by the wallet.
 
I believe Mycelium supports sweeping, via the Accounts > Settings > Cold Storage tab. See our guide to sweeping here:
 
https://99bitcoins.com/know-more-private-key-import-vs-sweep-difference/
 
Finally, bitcoins exist as records on the public blockchain and they’re not stored within your device. What your device stores is the private key which enables signature operations (such as spending) from addresses on the blockchain. It’s a subtle but important distinction.

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