Chas - LOL ! I had simply never ever noticed the battery icon on the pump screen - I've always 'gone down a screen' to see what it is! - where it tells you the actual %age. I expect if I could be bothered to plod through Roche's version of War & Peace I could find out whether the icons on both the pump and handset, plus the written %age screen all refer to the AAA batt or if any of them make reference to the internal battery - but in truth as long as the thing has a working battery (and of course the alarms work as long as there's a spark in the AAA although it won't do anything else, so probably a long long time before that one dies - so would you ever need to know, wouldn't you simply assume it was fine as long as there was a decent AAA battery in it?
I'll try not screwing the black bit 'across' quite so far next time - I've always thought there must damn well be a way that no-one had bothered showing me and hadn't been obvious to me, but as I've said before (not sure if it was to the forum at large, though) I didn't really have a very good 'handover' onto it in the first place - and that's involved more faffing about recently for everyone involved (Roche, the hospital and muggins AKA pig in the middle LOL) - however that's hopefully all water under the bridge now.
And - the handset battery - not understanding initially that it positively relies on being charged 'little and often' because of what we're used to with phones, cameras etc - I simply wasn't charging them often enough, so they were dying on me. Add to this that the charger we always used on 12v perfectly successfully simply didn't have enough oomph - though according to its markings it did - to do the job. Changed to a different adaptor - which we tested over a weekend away in the Moho when we were on EHU anyway so we had the choice, and it's been perfectly fine on 'just' 12v (with the 2 x solar panels on the roof doing their job with the 2 x 12v habitation area batteries keeping them both fully charged) ever since. I very very rarely need to test during the night and living in a bungalow or away in the van, the thing is only ever a few steps away in any case when it's on charge.
I'll see what happens next time a change a cartridge with the battery level and if it's still down then up, I'll ask Roche. Probably need to order supplies before Xmas though not quite ready yet, so they can both wait for the first week in Dec for that.