radio failure

We have got into the habit of only using one of our two batteries. It is kept topped up by the solar panel, so the second battery is just kept in reserve. Today I decided that we should let the second battery have a bit of a top up, so switched from battery 1, to both, to battery 2 while under way with the engine. 

In retrospect I have a vague memory of reading that this is a bad idea, but I did not remember at the time. 

The radio immediately started misbehaving, putting out a lot of static and the squelch button did nothing to stop it. I think I must have fried the radio somehow with my battery shenanigans. 

Luckily we still carry the old Swiftec radio that came with Robinetta as a spare, and have pressed it back into service. This is the second time we have needed it because the iCom failed. The "new" radio is out of guarantee now, and I suspect it will be cheaper to buy a replacement than get it fixed. Time will tell.