Battery cut off switch

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Remyd
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Forename: Remy
Surname: Dubois
Location: Buckingham

Battery cut off switch

Post by Remyd » Wed Dec 30, 2020 5:04 pm

Fitted a battery cut off switch and new battery to the mg today. Pretty straight forward and easy job even for a newbie like me. Planned the work in my head well in advance and it was plain sailing.
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Remy Dubois
1971 MGB GT

Dave Wheatley
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Location: SW Scotland

Re: Battery cut off switch

Post by Dave Wheatley » Wed Dec 30, 2020 7:29 pm

Well done. I've had trouble for a few months now with battery going flat after a few days standing. I would want my cut off switch to be more accessible though. Blooming daft place to site a battery when there is plenty of room under the bonnet!
Isuspect my flat battery problem could be my cheap and nasty radio with the memory live wire.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

Ian Fozzard
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Re: Battery cut off switch

Post by Ian Fozzard » Wed Dec 30, 2020 8:02 pm

Dave, my cutoff switch on my BGT is on the bulkhead just behind the passenger seat. Easy to reach from the driving seat. It interrupts the negative earth cable so is very easy to fit.

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

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Tom Brearley
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Re: Battery cut off switch

Post by Tom Brearley » Wed Dec 30, 2020 8:59 pm

A really good mod for working in the electrical system, and also handy as an immobiliser if the switch is the removable 'key' type. You just need to be aware if you have passengers in the rear, or any bags stowed behind the seats, that the switch might accidentally get knocked, killing the ignition! Guess how I know...
1973 MGB GT
Mallard Green / Autumn Leaf

Ian Fozzard
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Re: Battery cut off switch

Post by Ian Fozzard » Wed Dec 30, 2020 9:01 pm

Also kills the alternator if the engine is running when the battery is disconnected!!

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Dave Wheatley
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Re: Battery cut off switch

Post by Dave Wheatley » Thu Dec 31, 2020 9:51 am

Thanks Ian and Tom.
I think fitting the key type switch should solve the accidental switch off problem.
Ian how did you route the negative cable to your cutoff switch? On my car, single 12v type, the negative terminal is towards the rear of the battery "box".
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

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B Faiers
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Re: Battery cut off switch

Post by B Faiers » Thu Dec 31, 2020 9:56 am

Just a quick warning.... If the switch is the red removable 'T' shape key type.

Be aware that the plastic key is not hard wearing and after some time the end will wear/compress and not have enough length to push the contacts in the switch together. I cured the problem with a self tapping screw in the end of the key, but not something you want to be doing on a cold dark night. The other altenative is a muti-jointed passenger who can reach behind the seats to push and hold the key in place whilst you drive ;)

My final solution was to buy a better quality switch with a non-removable key. As the twist switch is black it hardly shows against the black carpet so is not obvious to the casual observer.
1964 MGB Roadster
1958 MGA Coupe
1926 MG 14/28 Bullnose
2012 MG 6TSE
2003 MG ZS180

Ian Fozzard
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Re: Battery cut off switch

Post by Ian Fozzard » Thu Dec 31, 2020 10:15 am

Dave, this is what I did:

1. Remove original cable from battery to earth
2. Buy new cable with two ring ends. Make sure it is long enough to reach from original earth point to battery switch.
3. Assuming the battery switch has two posts with nuts, as I believe they all are, attach original earth cable from battery negative to switch post (it will probably require a different orientation).
4. Attach new cable from original earth to switch.
5. Hole in the rear bulkhead requires to be in location giving space for switch body in battery box, behind passenger seat. Key sits conveniently to hand behind seat.

I have the two 6 volt batteries, so you may need longer cables?

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Ian Fozzard
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Re: Battery cut off switch

Post by Ian Fozzard » Thu Dec 31, 2020 10:26 am

B Faiers wrote:
Thu Dec 31, 2020 9:56 am
Just a quick warning.... If the switch is the red removable 'T' shape key type.

Be aware that the plastic key is not hard wearing and after some time the end will wear/compress and not have enough length to push the contacts in the switch together. I cured the problem with a self tapping screw in the end of the key, but not something you want to be doing on a cold dark night. The other altenative is a muti-jointed passenger who can reach behind the seats to push and hold the key in place whilst you drive ;)

My final solution was to buy a better quality switch with a non-removable key. As the twist switch is black it hardly shows against the black carpet so is not obvious to the casual observer.
I have these red keys in my BGT and Midget (and in other cars I've owned). Never noticed any wear at all and I disconnect whenever parked.

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Dave Wheatley
Posts: 161
Joined: Fri Sep 28, 2018 4:55 pm
Forename: Dave
Surname: Wheatley
Location: SW Scotland

Re: Battery cut off switch

Post by Dave Wheatley » Thu Dec 31, 2020 10:32 am

Ta for the tip B Faiers!

Thanks Ian, it was how you got the cable through the bulkhead that I was wondering. Thought there might have been an existing hole!

While we are on about batteries, does anybody else have trouble undoing the lid "screws"? As I undo say the third screw, I find that at least 1 screw that I have undone has done itself up again. Very exasperating, and the last one has always seized up anyway. I am tempted to cut the screws off, and install large self tappers.
Edit. Is there a name for the lid screws? Polite answers only please!
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

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