Optimate chargers.

[Barbel Mick]

If your battery is normally on the Optimate, or if not, put it on for a week before you go away, then disconnect it before you go away. It will be OK for a week or two, then, when you get back reconnect it. 

[Pete O Tube]

If you want to be certain as to whether there's any drain while the Optimate is unpowered, use your multimeter set to mA (and in series not parallel (as when checking voltage)).

[nigel s]

Ta Gents,good advice .
What with the ridiculous price of batteries at the mo,the days of replacing my battery every other year as a matter of course (Whether it needed it or not) are long gone.

[Ianmc]

   You could always check the charger with a multimeter on the “diode check“ setting on the clips when they are off the battery and the mains switched off.
That would tell you accurately whether there is anything feeding back.

[nigel s]

 

[Robotstar5]

Got no complaints about Optimate chargers apart from they only seem to last about 10 years  my bike's been parked in the garage on one for the last 3 years without any issues, it started OK a few weeks ago so the battery must be good.