Sorry if this has been asked before but I cannot make the forum 'search' facility work (Firefox, latest issue). Anyway, having been in use in hot weather since 2005 my 700 battery is not holding a good charge. I am an electronics engineer with experience of working on all kinds of the latest production kit so I would like to buy and replace the battery myself. Can anyone advise me of the battery type (or alternatives) and, ideally, any service notes on how to change the battery. Maybe there is also a lithium backup battery on the board that could be usefully changed at the same time? Many thanks.