Moving from Bitcoin Core to Electrum
Bitcoin Core, the “full” Bitcoin client, uses a lot of disk space to store the blockchain. I use GdMap to clean up my SSD and was recently shocked to see how many GBs are occupied by those files. So I decided to join the dark side and switch to a lightweight wallet. There are several of them around of which I chose Electrum. The only trouble I had were my old (donation) addresses that are too much of a hassle to change. I seem to have solved this problem by creating a second wallet in Electrum and here’s how I made it:
First, I imported private keys for all needed addresses from Bitcoin Core. In Debug Console I typed
dumpprivkey "<address>" for every address I wanted to keep.
Then, I started up Electrum, selected File — New/Restore and entered all the keys I obtained in previous step. If you do that, pay attention to all warnings and remember to backup this wallet — you won’t be able to recover it with your seed.
After that I was able to use my old addresses to receive and send Bitcoins in Electrum. Minus the gigabytes of blockchain data.