Remote battery isolator?

[Rich H]

Hey guys,
The Esprit has a battery drain of 0.25A so is killing batteries due to the crap alarm but I'm really not in the mood to strip it all out
It's buried in the centre console and its all wired into the immobilizer and central locking.

What I want is a remote battery isolator so I can wire in a switch somewhere in the cabin and isolate the battery (Which is in the boot)
I know them as battery contactors but the only ones I've found are either massively expensive solid state things or have pathetic load specs.

Any ideas where I might find a decent contactor cheaply? It's only a big relay really...

(Aircraft ones are all 28V - I've checked!)

Cheers
Rich

[Shug]

Cheaply is your issue - all the ones I've seen are for motorsport, hence pricier than they need to be.

Surely a man of your electrical nouse can rustle up the parts you need from inside an old telly?

[robin]

There is no easy solution to this problem, not least because you need the system to be able to cope with the starter current when engaged.

The red T-bar type thing you often see on the outside of caterhams, etc., might well work as being manually operated it can have big contacts that take the load and there is no danger (really) of it being operated during cranking such that it has to deal with connecting or disconnecting 100A on the fly.

The other option is to isolate the alarm system instead of trying to completely disconnect the battery. What's the betting there is a fuse you can remove that will reduce battery current to zero - all you now need to do is to either remove that fuse forever, or if the fuse is required to make the car work, wire a relay into that circuit in series with the fuse, and have the relay controlled by the ignition, or a toggle switch on the dash board (in fact if the fuse is relative small, e.g. 1-3A you might get away with just the toggle switch, but I would use a relay to be safe).

One thing to watch out for is if there is a secondary battery inside the alarm system somewhere that is charged from the main battery/alternator ... if this is the case then when you disconnect the main battery you'll cause this secondary battery to discharge and that might make the alarm go off/go wonky/break completely.

Cheers,
Robin

[Rich H]

Thanks guys,

Alarm doesn't have an internal battery, it's too old for that.
Trouble is the ingition is wired through the immobiliser so complicates things a bit.

I have a 'discarnect' fitted that isolates the battery at the moment but it's a pain as I need to faff around in the boot.
I think the battery master type key is the way forward, but I was hoping there might be a nice easy electrical option - clearly not!

Cheers
Rich

[robin]

I think there is - just isolate the fuse that is the cause of the current drain and fit a relay in series with that fuse - I cannot believe the immob/alarm is unfused?

[Rich H]

Sorry yes the alarm has 3 fuses for some reason.
Need to investigate again

Ta

[Stevie]

RS Components do a 100A battery isolator switch for about £15
RS Stock No 325-4840.

http://uk.rs-online.com

[Rich H]

Thanks but I wanted an electric one, the switches are a last resort

Really I need to find adn kill the fault of course...

[neil]

This looks like it will do what you need - http://www.rawcomponents.co.uk/100-amp-12v-relay.html

[Rich H]

Thanks but I need the spec sheet or there is a good chance the starter current will blow it to bits...
They are usually rated at 500A for 5 secs or similar for starter loads.

[neil]

Thanks but I need the spec sheet or there is a good chance the starter current will blow it to bits...

Surely that's half the fun! Just make sure you video it

[Rich H]

no

[Shug]

no

You've changed....

[Rich H]

I'll make my own instead

[Sanjøy]

There is no easy solution to this problem, not least because you need the system to be able to cope with the starter current when engaged.

The red T-bar type thing you often see on the outside of caterhams, etc., might well work as being manually operated it can have big contacts that take the load and there is no danger (really) of it being operated during cranking such that it has to deal with connecting or disconnecting 100A on the fly....Robin

Looking for something like this after I have killed another battery in the 340 after letting it go mega flat then putting 12 volts across it. Thoughts on an easier install option? Anything that could be put on top of the actual terminal?


S