Vehicle alarm.

[xsparks]

I was surprised to find that my brothers motorhome alarm is fed from the leisure battery. Is this normal practice? Mine is supplied by the vehicle battery. It just seems to me that the leisure battery might have demands put on it that would render the alarm inoperative

 

[ctc]

Mine has its own battery, when it goes flat you get phone calls telling you they can't make contact with it. The battery is only charged when the alternator is charging, if it had been run from a battery charged on EHU, it would be working all the time.

 

[Stealaway]

I was surprised to find that my brothers motorhome alarm is fed from the leisure battery

I am.
Maybe the fitter couldn't be bothered to check the 12v supply he found.
Most vehicle alarms are powered by the starter battery - mine have always been.
It should be hard to change it over

 

[Spriddler]

I don't think that's normal practise but perhaps it was thought better to have the leisure battery run flat than the starter battery which would immobilise the vehicle (and render it impossible to charge it via the alternator).