Alarm/Immobiliser run off leisure battery?

[spud350]

I don't use the van for long trips often but do try to run it on the weekends. However recently the alarm was disabling but the central locking not working. Checked the starter battery which was OK at 12v but the leisure battery which isn't used except the the usual blinds,interior lights, radio was at 3v.
Started the engine and there is 14v at both batteries.

Put a battery charger on the LB and tried the alarm again and it works, so does the central locking, so it looks like the LB is powering the alarm/immobiliser.

Why would the LB be now powering the alarm? Would the alarm be powered from a permanent live on the interior lights or something which is now powered by the LB?

Anyone else have this issue?

cheers Spud.

[Simon Jones]

Most alarms work by sensing a voltage drop when the interior light comes one when a door is opened. If you have interior lights running of the LB, but the alarm on the starter battery, then you can get some strange side effects. It sounds like your alarm is powered by the LB which probably would be correct if your interior lights are powered from there too.

I guess the solution is not to allow the LB voltage to drop too low otherwise the alarm will stop working. Have you considered a cheap solar panel from the likes of Maplins to keep it topped up?

[spud350]

The LB is willinton kit so I suppose everyone who has this would be the same?

I'm just guessing the alarm is on the interior lights but it makes sense what you say. I have a solar panel on the SB so it looks like I'll have to get another.

[jaylee]

Some alarms are also triggered by a negative switch on the doors which is a better option in my view than the voltage drop sensing type alarm, if you have ever had to lock & leave yer hazards or side lights on the volt sensing variety don't like it..?!!

[321Away]

you need to switch the alarm power over to the main battery, the central locking and the alarm controlled locking are 2 different things, the alarm usually controls only the priamry motor in the drivers door, the vehicles central locking is easily switched over to LB, there is a difference. Beware where you take the power from tho as a few main +ve wires can be easily knocked out if some1 knows what they're doing, so unless your using battery backup unit (thatcham grade), your alarm can be bypassed quite quickly.

Julian

[briwy]

Disconnect the leisure battery and if the alarm still works it must be running off the starter battery.

[Simon Jones]

My previous Clifford alarm had built-in battery so it would work when the main battery was disconnected.