Disconnect 12 volt battery

[Honey Ward]

We will be away for 3 months and have been advised to disconnect the 12 volt Battery. We have disconnected the cover, and need to know what tool is required to actually disconnect it. We will not be removing Battery. Thanks. 

[Hadrian1]

A suitable spanner ?

Personally I would just leave it and charge it when I got home.

[forkingabout]

For safety always disconnect the - NEGATIVE terminal first & reconnect it last! 

 

[jthspace]

8mm spanner from memory, but have a 10mm with you just in case!

As @forkingabout says, it's very important to remove the negative (black) connector first - and tie it back so it can't accidently flop back towards the Battery. 

When you undo the positive terminal (red), the spanner will undoubtedly touch the chassis as there is little room to maneuver so it's imperative that the negative lead is disconnected to avoid a short.

[hind]

Wouldn't disconnecting just one terminal (preferably negative one) be enough? Self-discharge rate should be low enough to keep the Battery in acceptable condition for 3 month of storage.

[jthspace]

42 minutes ago, hind said:

Wouldn't disconnecting just one terminal (preferably negative one) be enough? Self-discharge rate should be low enough to keep the battery in acceptable condition for 3 month of storage.

I thought that, I expect you are correct though.

[jthspace]

Not sure there is enough room under the seat, but I've got these fitted to my MX5's for when they are not used during the winter.  £6 on Amazon

[flash22]

26 minutes ago, jthspace said:

Not sure there is enough room under the seat, but I've got these fitted to my MX5's for when they are not used during the winter.  £6 on Amazon

More trouble than they are worth, OK for more vintage cars with no complex electronics

[MikeSh]

3 hours ago, hind said:

Wouldn't disconnecting just one terminal (preferably negative one) be enough?

Yes,  and safer too. The +ve terminal/clamp should have a cover over it which is best left secure. The -ve clamp just needs to be secured away from the Battery -ve terminal (or wrapped in something insulating) so it doesn't remake the circuit and defeat your efforts to disconnect it.

[jthspace]

2 hours ago, flash22 said:

More trouble than they are worth, OK for more vintage cars with no complex electronics

My Eunos is 1993 and my Mk4 is 2018 - I use these on both when they are under CTEK charge - the CTEK confuses the stop/start system on the Mk4 as Mazda use a 25v system and a very large capacitor. The alternator switches off when not needed and relies on the capacitor - all part of the CO2 reduction system.  Without the above Battery switch, the stop/start reset can be a pain in the a*se.