When we got a Sunamp Uniq heat battery last year we were a bit surprised to discover that it had no lights, switches or user interface of any kind. You can't tell whether it's charging or not, how much charge it has in it at any time (i.e. can you have a bath or not) and you can't tell it to start or stop charging. It just sits there doing what it's configured to do (It does that very well and we're very pleased with it.). So to cut a long story short I made a little box that displays charg