Scottish Elises

Does anybody have experience with a battery isolation switch on their Lotus (particularly S2 and onward with an immobiliser)?

Since I got my Porsche the Lotus has been relegated to a lock up with no power so can’t be on the trickle charger, it was being started every couple of weeks but even at that the battery has struggled recently.

It’s been suggested to fit a motorsport style isolator which would prevent the immobiliser draining the alarm but I have some reservations:
1- The remote locking wouldn’t work and I seem to remember the door can’t be unlocked using the key in the barrel- would I have to leave the car unlocked or at least the engine cover popped?
2- Would disabling the alarm and immobiliser (by removing power) invalidate the insurance?

Any advice would be appreciated, thanks

It would need a decent run to recharge the battery fully?

You could disarm the alarm/immobiliser, disconnect the battery then lock the doors with the key (like you need to do on a ferry). The key just disables the lock barrel. The car would would then at least have doors and engine cover 'secure'.

To get going again, open the doors with key, pop the engine cover and reconnect the battery.

Also there are charging posts in the front nearside service access panel. These can be used to for power if the car is locked and the battery flat.

I'm not sure on the insurance, it's pretty immobile with a battery isolator or the battery out but we know what insurance companies are like...

alicrozier wrote:It would need a decent run to recharge the battery fully?

Yes, just idling will have helped a little but not for the 6 months it's been sitting...

alicrozier wrote:You could disarm the alarm/immobiliser, disconnect the battery then lock the doors with the key (like you need to do on a ferry). The key just disables the lock barrel. The car would would then at least have doors and engine cover 'secure'.

To get going again, open the doors with key, pop the engine cover and reconnect the battery.

That sounds like the solution, my experience was trying to unlock the dead car with the key which of course didn't work. If it is already unlocked and you turn the key in the barrel- disabling the barrel, the door wouldn't technically be locked but couldn't be reopened without the key which is good enough I think.

alicrozier wrote:Also there are charging posts in the front nearside service access panel. These can be used to for power if the car is locked and the battery flat.

I didn't know about these

alicrozier wrote:I'm not sure on the insurance, it's pretty immobile with a battery isolator or the battery out but we know what insurance companies are like...

I agree it's pretty immobile, but the kind of technically I'm sure insurance would jump on if the question was to arise.

Thanks for your help.

I think it'll needs more than idling rpm to charge. I've always gone by 30 mins at minumum of 1,500rpm will give a good charge to sit for a couple of weeks (more revs than that wont help) - hence take it for a drive and keep the revs up a bit if sat idling at traffic lights etc.

Repeatedly starting and just idling may actually make things worse...

Do you have any scope to connect a solar charging panel to the battery


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Big thumbs up for battery isolating terminals.

I've seen something like this used effectively in just your situation.


You can leave a car for months in a lockup and then return and simply screw down the connector and off you go. You'll still need to give it a charge every now and then if you do short runs but in general this works well. It can also be viewed as an effective imobilser.

Thanks for the info, I hadn't seen the isolation terminal Ferg suggested but will look in to them, I was thinking along the lines of a motorsport kill switch.

Renny, no scope for a solar charger, fortunately my lock up is reasonably watertight and with no windows.

As Ferg has indicated the battery isolating terminal is the easiest. I had the same part fitted to my Elise in the image Ferg has upload and it was totally fine.

Ferg wrote:Big thumbs up for battery isolating terminals.

I've seen something like this used effectively in just your situation.


You can leave a car for months in a lockup and then return and simply screw down the connector and off you go. You'll still need to give it a charge every now and then if you do short runs but in general this works well. It can also be viewed as an effective imobilser.

What he said.

I've fitted a few of these to different cars

£4 on Ebay

KennyT wrote:Thanks for the info, I hadn't seen the isolation terminal Ferg suggested but will look in to them, I was thinking along the lines of a motorsport kill switch.

Renny, no scope for a solar charger, fortunately my lock up is reasonably watertight and with no windows.

A long drill through the wall and mount the panel outside?

Then a charge controller inside and then 2 wires down to the car

Great thread! Just ordered 3 battery isolating terminals.