Thanks everyone for their help. I have been working on this and think I now have it clear. I hope the following is helpful and please let me know any corrections, tweaks or issues.
EXPLAINING AND SETTING THE TIMER CHARGE SYSTEM ON OUTLANDER PHEV
If you have or set up cheap-rate electricity at night, then you should set up the timer so that you get home and plug in, knowing that it will only commence charging once the cheap period starts (or at least avoiding charging in the highest rate).
However, if you ever want to charge elsewhere (eg at work or fast charge station) during the day, then you don’t want the timer to operate on these occasions, or you’ll come back having plugged it in only to find it has not charged at all!
For this reason, you can set ‘Location’ – once this is properly set, the timer works only when the car is at the selected location (eg home), which is automatically determined via GPS, but in any other place the timer is disabled, so wherever else you lug in, it charges immediately.
However, when selecting ‘Location’, it has to show as registered. Initially I had set home as the street address (but it was not the exact parking location) and when I selected Location it said ‘not registered’. I had to delete and re-register the home address and use ‘TUNING’ arrows to register it precisely. It now shows as ‘Registered’ and works as it should:
Now for the timers!
For this explanation, let’s assume your home electricity rates are as follows:
Cheap rate 9pm to 9am
Shoulder (middle) rate 9am to 3pm
High rate 3pm to 9pm
BUT at weekends it is always Cheap rate.
You can set three different time periods, eg 1 could be cheap rate, one could be shoulder and the third high – but this would NOT be a good solution (for example you’d never want the car to charge at HIGH rate if you could avoid it!). To set the timers needs more logic.
You can only set one timer per day. So if you want to charge the car from midnight to 9am (cheap rate) then you could set timer 1 for 00.00 to 09.00. BUT if you did this, you could not charge it from 9pm to midnight (unless you disabled the timer, which is a pain and I at least would forget to turn it off, or to turn it back on!).
Luckily, there is a partial solution. The timer does not only operate in the day chosen. So for example if I chose TUESDAY for timer 1, and selected timer 1 to operate from 9:00 PM to 9:00 AM, this is actually telling the car to START CHARGING ON TUESDAY AT 9:00 PM (which you would expect) but to CONTINUE CHARGING INTO THE NEXT DAY AND FINISH CHARGING AT THE NEXT 9:00 AM (ie WEDNESDAY) – like an airline flight, it should say (Next Day)! (I imagine that this would be overridden by the Wednesday setting if it conflicted, eg if timer 2 was selected, which was set to turn on the charger at 6:00 AM and off at 7:00 AM, it would stay ON at 6:00 AM as it is still on from the previous day’s instruction, but would go OFF at 7:00 AM rather than timer 1’s 9:00 AM, but I have not checked this).
The weekend transition.
Because I have cheap rate all weekend, and also tend to drive in and out of home frequently during the weekend, I want the car to charge whenever I plug in for a top up. So I could select timer OFF for Saturday and Sunday.
However, I got back at 10:00 PM on Sunday evening with an empty battery, and plugged in, and it started charging (a click and a solid green light). But come Monday morning it was not fully charged. What happened? The timer was OFF for Sunday – so it charged from 10:00 PM until the end of Sunday, ie 2 hours charge. But when Monday started, timer 1 (which is selected for Mondays) came into force. And timer 1 is 9:00 PM to 9:00 AM. So as Sunday moved into Monday, the charging was switched off – Monday’s charge timer said OFF UNTIL 9:00 PM, so it did as it was told, and switched off!
I have now resolved this by selecting another timer setting (timer 2) for Saturday and Sunday. Timer 2 is set from 0:10 AM to 23:50 PM. BUT AT THIS POINT I ALSO USED THE ‘FULL CHARGE’ OPTION.
I found the wording confusing, but have worked out that selecting ‘FULL CHARGE’ ON on the right side of the ‘Timer Settings’ page will OVER-RIDE THE TIMER CUT-OFF TIME whereas selecting ‘FULL CHARGE’ OFF really means ‘TIMER FULLY ON’! (That is, when ‘Full Charge’ is set to ‘OFF’ the charging is determined solely by the timer times, but if ‘Full Charge’ is selected to ‘ON’, the charging will start according to the timer ON time, but charging will continue until fully charged regardless of the Charging Timer's OFF time).
So on Saturday and Sunday, the timer is now set to charge any time (between 0:10 AM and 23:50 PM, but to continue charging until the battery is full. So now, if I get home at 11PM on Sunday evening and plug in, instead of switching off at 23:50 PM and me finding barely any charge on Monday morning, it will get its full charge before going off!
(One potential problem remains: If I get home at 1 AM, the timer will already be in the Monday regime, ie, don’t charge until 9:00 PM. So I will need to be in a fit state to switch the timer off in order to get a full battery in the morning. But if I wasn’t, I shouldn’t be driving!).