Thx all.
I have an Internatrix alarm, did not mention this in the original post, as not many use this brand.
Never had a problem before, but lately I get three weeks with the alarm off and the battery does not have enough left for a start.
Just checked, the alarm pulls 3.8mA when unarmed, which is to specifications, battery takes a charge well and charging system runs battery at 14.5V when idling. Everything in spec, so my battery at just over two years old is probably getting tired.
Have not done the rectifier recall yet, but everything tests out fine.
By the way battery life on my alarm pager/remote is around four months.