Well thank you very much man! I am still lucky things still work, but I think we can safely say that using a lower voltage power supply for this cradle was okay though.. wouldn't you? I could see it the other way around with a higher voltage use than what it came with causing problems, but not a lower voltage one.. Let me know if I'm wrong!
You are right - you will almost always be safe with a lower voltage rather than a higher one. (The very rare exception is units with badly designed switched-mode voltage regulators that can't handle the higher current that they may take at lower input voltages - best not to worry about that!).
But different appliances will vary in their ability to withstand incorrect polarity. Many will use a blocking diode, so if the polarity is wrong they just won't respond at all until the supply polarity is corrected. Some others will use a reverse diode across the input to blow a fuse if the polarity is wrong. That will protect the expensive electronics but will stop things working until the fuse is fixed. And some devices will not have any protection - they will normally start to emit smoke after 5 - 10 seconds if the polarity is wrong.
