John Stumbles wrote:


Even with the lower-capacity battery the panel is designed for its power
supply/charger is going to have to sustain its max output current for many
hours: long enough to cook a poorly designed PSU (not that I'm saying the
PSU might not be poorly designed :-). So with the larger battery the PSU
_should_ not suffer.


At last, some common sense!



Putting two batteries of different ages and capacities in parallel is
probably not a good idea.



Not especially, but not as dire as you think.


If you want a serious backup supply (maybe for emergency lights as well as
the panel) you could get a caravan/boat leisure battery (circa £30 for 85AH
from motorists discount centres) and a charger from Argos (£25 IIRC) which
will drop back to a maintenance charge for maintaining a float supply.


Overkill, but a neat idea.