Alarmnet 7835C - using main control's battery in place of on-board battery for backup

[Mike Cooper <mcooper674@xxxxxxxxxxxxxxxxxxx>]

Question for anybody experienced with AlarmNet transceivers....I'm
planning on adding an AlarmNet 7835C to my existing system and would
prefer to have the battery backup of the main panel supply the 7835C
instead of the 0.7 amp-hour battery that comes with the 7835C, which is
harder to locate an identical replacement for.

So, if I were to answer no to programming question 33 (Battery present?
Y/N), what exactly does this disable - the 7835C's on-board charger,
low-battery monitoring, or both?  Or would it also disconnect the
battery terminals altogether so that the unit would not accept any DC
current from those terminals during an AC outage?  Knowing if the
charger still functions even with a no to Question 33, I assume, would
dictate whether I need to wire a diode into the positive lead between
the 7835C battery positive post and the Vista control's battery positive
lead.  Your thoughts?

Best regards,

Mike