Battery disconnector/Kill switch - Yes or No?

[MFWL]

Dear all,

Against the background that I regularly find my Chimaera with an (almost) empty battery, I contemplate to have a battery disconnector applied, so that the battery discharges less quickly. Now I learned from my initial research that taking the battery "offline" affects the control unit as such that the Eprom(s) are reseted each time the battery is taken of the net.

What is you opinion on this matter? Go for it or leave it?

BTW: Using a permanent charger is - unfortunately - not an option now, since there is no electricity in my garage...

Best,

Max

[richard sails]

Hi Max,

I have a battery disconnecter fitted to my Griff (Pre Cat 4.5BV on the Lucas hot wire system).

I operate it every time I walk away from my car, I would not be without it as so many cars have been destroyed by electrical fires, other than fuel pipes its the biggest cause of fires in TVR's.

If you have the same system fitted, then its true that the adaptive data is lost when the power is removed, but this is re-learnt by the ECU in a couple of minutes, the only affect I have ever noticed is a slightly more erratic idle for a minute or two when first powered, but if the engine is cold its slightly erratic anyway.I am not talking very erratic, just a couple of hundred rpm at most.The ECU does not loose anything in the EEPROM which includes the maps.

My recommendation is to fit an isolator switch, preferably somewhere you can get to it quickly to kill all the power on the car, if only for fire protection.

[grumbledoak]

I had an isolator switch with a removable handle fitted to mine. Much better than breaking in all the time.

[Wicker Man]

Be aware that, after several months without power, the immobiliser can give up the ghost.
Perhaps you could rig up a solar panel as a trickle charger?

[Loubaruch]

Wicker Man said:

Be aware that, after several months without power, the immobiliser can give up the ghost.
Perhaps you could rig up a solar panel as a trickle charger?

I would disagree.

For 15 years I isolated the battery in my Griffiths over the winter months from November until April and the old Meta system never failed during this period. It did eventually fail while it had been running for a few months in the Summer but as it was then over 21 years old so not surprising. The Meta was replaced with a Toad system ( much better in all respects) and that has also been happy being isolated over the winter. Unless it is an insurance requirement to maintain the alarm/immobiliser system i.e. parked outside I cannot see any disadvantages in isolating the battery only positive ones!

www.bertram-hill.com

[Plan B]

I’ve used a battery isolator for 7 years. When reconnecting as the OP mentioned, the ECU has to re-learn emission settings but the car is entirely drivable immediately. The immobiliser (Meta) usually needs to be cycled a few times before it gets itself sorted out. I usually top up the battery once a month throughout the winter period Without the immobiliser that would need to be a weekly event.

[Penelope Stopit]

Have you bothered to check for what the current drain is?

[Classic Chim]

Penelope Stopit said:

Have you bothered to check for what the current drain is?

It’s nearly always alarm parasitic drain.
It happens on modern cars too
Any car left alarmed for weeks or months will eventually drain the battery it seems, well my mates forecourt is full of modern cars with flat batteries .

[MFWL]

Hi folks,

Many thanks for your input!

Problems with the immobilizer will not be of the essence, since I will have that removed soon. So I guess that the answer - at average - is yes and a switch will be installed (perhaps on the underside with the advantage of being accessible when the car is locked).

Best regards,

Max

[Penelope Stopit]

Penelope Stopit said:

Have you bothered to check for what the current drain is?

Will rephrase that

Have you measured how many milliamps/amps are being drawn from the battery?

There could be something energised that shouldn't be

Yes, a master switch cuts a current drain but doesn't fix a fault

[bobfather]

My insurer requires me to lock and alarm my car when not in use, even when it is stored in my garage. I can't do that if the battery is disconnected

[Loubaruch]

Penelope,

If you are so keen to know residual current drain on a Chimera or Griffith why dont you just measure it on your car ?

[magpies]

Loubaruch said:

I would disagree.

For 15 years I isolated the battery in my Griffiths over the winter months from November until April and the old Meta system never failed during this period. It did eventually fail while it had been running for a few months in the Summer but as it was then over 21 years old so not surprising. The Meta was replaced with a Toad system ( much better in all respects) and that has also been happy being isolated over the winter. Unless it is an insurance requirement to maintain the alarm/immobiliser system i.e. parked outside I cannot see any disadvantages in isolating the battery only positive ones!

www.bertram-hill.com

the problem is that the OP's battery is being drained unlike yours (or mine) therefore has a problem which needs to be found, but in the meantime a battery isolator will stop that happening.

[MFWL]

I don not believe that my car has irregular drain (don't know for sure), since the battery lasts a few weeks until empty. But even for me as an electric-layman, it makes a lot sense that the immobilizer and the alarm suck too much energy for the benefit they contribute. This is in line with what I heard from a TVR garage here in our region. Hence, I decided to have the immo and the alarm removed. The car will not be stolen anyhow (not too many thiefs are masochists... )

[richard sails]

My immobiliser and alarm power up in the alarmed condition and need to be deactivated before I can start the car, So once the thieves have powered up the car after finding or bypassing the hidden power switch, they then still need to defeat the alarm and immobiliser.

[s p a c e m a n]

I've got a solenoid isolator kit a bit like this fitted

https://www.ebay.co.uk/itm/333403179514

Means that I've just got a little waterproof toggle switch hidden on the outside of the car so that I can lock it and then isolate the battery. I normally remove the ECU if I'm leaving the car for a few days, much better than any immobilizer. If anyone coming to steal your car comes equipped with a spare ECU you was never going to stop them anyway.

[QBee]

In summary, kill switches are a good thing:

1. They allow you to stop flattening the battery (my Odyssey battery was isolated for 9 months last winter/spring/summer and was still 75% charged when tested prior to turning back on)
2. All Chimaeras drain the battery in a matter of a few weeks at best if left connected - the clock and alarm do the trick for you
3. You are so much more likely to isolate the battery before working on the car if it is as easy as flipping a switch, and it will do less damage to your battery terminals

Just think before you install it, because you will disable the doors, boot and alarm. Mine was installed in the boot, where my battery is, so I have to remember not to slam the lid while the battery is isolated. The ideal location is somewhere outside the car and within reach.

As Steve D says, a a lot of TVR fires these days are caused by things shorting onto the battery, or by frayed or knackered wiring. In my mind, fuel hoses come second.
Strangely enough, as i was driving mine yesterday I saw a car on fire on a main A road. The fire was under the bonnet, and by the time I was passing, a nearby garage had exhausted two large fire extinguishers on it to no avail - the car was well alight and on the way to being a burnt out shell. It was a 12 year old BMW. So it's not just our cars, but fibreglass burns particularly brightly.

[Classic Chim]

Penelope isn’t to know what we know maybe because we all know they drain the battery if stood for weeks on end alarm enabled..
Now there may well be another reason for it on any given car , a particular fault with that car, in essence yes it’s a good idea to check but as most of us owners already know it’s the alarm.
If you use your Tvr regularly your battery will never run flat as I drove mine for nearly ten years with no issues at all.
As o/p has pointed out, he doesn’t think he has issue anymore than the rest of us, including tonnes of modern car owners who leave cars enabled but not connected to a power supply end up with flat batteries.

[Penelope Stopit]

Someone has done the maths, saves doing some calculations and typing

.007A X 24 =.168 Ah's per day

.168 X 7 = 1.18 Ah's per week

1.18 Ah's X 5 weeks = 5.88 Ah's per month......

At 5 weeks a 100Ah battery bank would still be at 94.2% state of charge

At 5 weeks a 200Ah battery bank would still be at 97.1% state of charge


Newer stereos are even more efficient and I've measured them as low as .002A... That's just 1.68Ah's per 5 weeks




Wonder if these are any good?

Edited by Penelope Stopit on Friday 25th September 13:36

[s p a c e m a n]

I don't know how well a solar charger would work inside a locked garage

Make sure you fit a controller if you do buy one or you'll probably do more harm than good