Guys,
Having read this thread and knowing my laptop battery (LIon - three year old machine) had deteriorated to the extent of only getting fifteen minutes out of it, I decided to run some tests.
I charged the battery to an indicated full charge and then booted into the BIOS (did not boot to Windows) and disconnected the mains. I noted at what percentage of battery condition I got the first warning ("beep") of low battery and then at what percentage the machine "ran out" of charge (I had to sit by the machine whilst doing this).
The first cycle was 90% and 70% respectively. Clearly the battery or its reporting mechanism was way off so after reconnecting the mains (without booting) and charging I repeated it, booting to BIOS setup each time and running it down. I noted the readings each time and with each cycle the battery condition reporting and life improved to the extent that I can now get at least an hour plus out of a full charge and the machine shuts off at 0%. I ran this cycle a full six times and it took a full day.
The battery is still down on what it should be but it gives me a bit of breathing space before I'll have to replace it.
Clearly, the battery dislikes being "topped up" all the time ( I am usually plugged into the mains most days) but it is not practical to run the battery right down and recharge each time (particularly if you are working in Windows). I don't think any of us are doing the wrong thing by topping up - it is just unavoidable but the above may be of use to anyone who has battery condition problems and give you a bit extra life out of the baby.
By the way, I had to disable the "critical suspend" option in the Power section of the BIOS to stop the machine going into "suspend" mode when the battery got too low. Check your documentation.
Best!
HA