Autocom Logic L1 battery life with bluetooth

Can anyone shed any light on the expected battery life of an L1 logic system with the optional bluetooth module connecting to a Zumo 550?

I have spoken to Autocom on a couple of occasions and have received conflicting advice. One guy says that the L1 with decent quality batteries should provide ample life when bluetoothing (?) to a Zumo and another advises that the bulkier bike powered option is the way to go and would avoid a battery powered bluetooth set up even with NiMH rechargeables. I need the portabilty of the L1 but not if it eats batteries by the day.

Anyone had experience with this type of set up.

Regards

YL

Old question, but this still might be useful to someone ....
I have an Autocom Logic L-IW bluetooth, rider to pillion, set.
I use a cable to the Zumo satnav.
No music, 'phone etc fitted.
Very careful with the Vox settings but only get usually max of 8 hours out of batteries.
Say, two days riding. Sometimes less. They start to hum and whistle about an hour before they die.
Expensive,(How much??), Duracell type don't last any longer than the cheapest own branded ones, in
fact the best ones I ever bought were French "Carrefour" ones - they lasted nearlya week!

I got a week out of my batteries but only used it for music.