Stop alarm going off when the battery is disconneted

[Tooleater]

I leave my camper van parked-up for a month a time.

In the freezing cold weather, there isn't quite enough juice to start it when I return to it.
I repalced the lead-acid battery with a new AGM battery but still get the problem (almost enough power to start the engine but not quite enough I'm guessing there's a power drain somewhere).


I bought a decent quality battery disconnect with the aim of disconnecting the battery and locking the van with the key only... that all works fine but when I go to unlock the van (with the key) the alarm goes off (the alarm has a battery backup).

The problem is; I always collect the van very late at night (2am) and it's parked right infront of a row of houses (rented parking space).

Is the most practical solution to pull certain fuses instead, so the majority of equipment is disconnected but the alarm still gets power?
I know solar is a potential option - can that be fitted to a can with a pop-top?

Cheers
Al

 

[Dellmassive]

You could add a dash top solar panel that may help.?

Or possibly add a second portable AGM battery in the cab, that's connected in with the starter battery via the front 12v socket... You can use a small voltronic b2b resistor/diode based charger box that will allow a small trickle power flow to support the starter battery... effectively doubling the battery power and time the van will last. While parked.

Or disconnect the van battery backed siren. Or muffle the sound by covering up the sonder?

 

[Pete C]

Our van battery easily lasts 4 weeks if we leave it.
You could check what is drawing current, and also confirm how old the battery is.

Another option is a Noco or similar jump starter.

Pete

 

[Craig.]

If you have MFD, set the central locking to open drivers door only so when you disconnect the battery the rest of the van is already locked and leave the alarm deactivated when you pull the battery feed.

That way when you lock and unlock the drivers door with the key whilst the battery is disconnected, the alarm should stay silent.

Do you have any aftermarket items wired into the van, such as a dash cam?

 

[roadtripper]

If you have a camper with a leisure battery have you fitted something like the ablemail trickle charger so it can keep the starter topped up?

If you are parked on the street you probably don't want something that looks like the van is being left for a long time and might not be missed for security and a big panel on the dash might do that, but yes adding solar to the roof to charge the leisure and then that charges the starter is something many have done, even with a pop top.

 

[Tooleater]

Thanks everyone for your excellent thoughts & suggestions

I've had the current draw analysed - apparently it's all totally within spec.
The technician belives it was the combination of a really cheap, undersized battery (allbeit only a few months old - fitted by the seller) and the freezing cold weather.

I do like the idea of the B2B trickle charger from the leisure battery but as I sometimes go 6 weeks without visiting the van, I'd like to get the alarm sonder / siren turned off, so I can go with the battery disconnect option.

Apparently this can be done with a diagnostic tool. Does anybody know how to do it in VCDS / VAGCom please?

Thanks in advance
Al

 

[Tooleater]

You can use a small voltronic b2b resistor/diode based charger box that will allow a small trickle power flow to support the starter battery

The choice is pretty mind boggling! Some seem to be designed for when the engine is running only.
Do you know which model might be suitable for trickle-charging from battery to battery when the engine isn't running please?

 

[roadtripper]

I think @Dellmassive means this simpler device - though this isn't suitable if your LB is not a lead acid based battery:

Votronic 3065 Battery Master - Standby-charger 12V

<p>This Votronic charger is a great way to trickle charge your engine battery in a motorhome, Installed between the starter battery and the leisure...

www.roadpro.co.uk

The alternative is the Ablemail AMT-2 which is much more flexible but a bit more costly:

Ablemail AMT12-2 Battery Maintainer

<p>The AMT12-2 Trickle Charger has been designed to keep a vehicle’s starter battery charged and protected from damage during prolonged perio...

www.roadpro.co.uk

If you are just doing a cheap and cheerful additional battery hooked up to the 12v socket then the Votronic is fine, if you have an existing leisure install and want something fit and forget then the Ablemail might be the better route.

 

[Tooleater]

Thanks for the advice roadtripper, much apprecaited, I'll lookinto those.

The Ablemail looks great but it seems it's not compabile with AGM / Gel battery chemistry... bummer

 

[roadtripper]

The Ablemail should be fine, it's more configurable and it's a popular choice on the forum. The only thing you need to set is if the target battery is lithium or any type of lead acid (including AGM/Gel). It works by feeding short pulses of current when the voltage thresholds are passed, it's a trickle charger not a bulk charger so it doesn't need a highly specific charging profile.