Disconnecting battery.

[tangerinedream]

Originally posted this on Facebook as on there anyway and quick responses from other people who can't leave their phones alone. However, friendly though they are, nobody would/could actually answer the question, confirming that (hopefully) Pistonheads is where the true gurus reside.

I've got a bouncing rev counter and lots of threads on Pistonheads suggest replacing the big fuse. Embarrassingly, this will be the biggest car related job I will have undertaken, but God loves a tryer and we've all got to start somewhere. Before poking around down there, I understand I need to disconnect the battery, and that the recommended means of doing this is to disconnect negative first. However, there is no way on God's green earth I can do this on my car without removing the air box which is nicely sealed etc and which I really don't want to do. So, can I just disconnect the positive terminal instead or is that a really bad idea? If it's possible, what do I need to watch out for?

[ukkid35]

tangerinedream said:

So, can I just disconnect the positive terminal instead or is that a really bad idea? If it's possible, what do I need to watch out for?

Yes just the positive, that's what I do. But there is good reason to disconnect the negative terminal and that is because the entire chassis/engine is still connected to the battery, so there is a greater chance of causing a short (or a fire) by dropping something that touches the positive terminal and just about anything else. To be on the safe side put back on the terminal cover that came with the battery when new.

[Revvit]

Given the accessibility issues I've had a battery isolator/master switch installed. One turn and the battery is effectively disconnected without a spanner in sight. Not expensive to install and a handy addition in my eyes.

I've also had the battery shifted to the boot.

[tangerinedream]

Thanks Both - that's great. I'll find something to cover off the positive terminal properly (and great tip to keep the terminal cover when I next replace the battery).

[ukkid35]

Revvit said:

I've also had the battery shifted to the boot.

Great for weight distribution and COG, never did like batteries mounted high in the car. However any short right next to the fuel tank is going to be a much quicker disaster.

[Revvit]

I'll definitely not be wanting any petrol leaks

Given the number of other electrical components in the boot space it probably doesn't add much more of a risk, especially as I've had an auto electrician go other the entire car sorting out any gremlins.

Having said that, I am considering plumbing in an automatic extinguisher

[mike_e]

Make sure you keep the keys outside the vehicle or a door open when you reconnect the battery, the car will immediately lock itself once you hook up the battery.

[Mr Cerbera]

ukkid35 said:

Yes just the positive, that's what I do. But there is good reason to disconnect the negative terminal and that is because the entire chassis/engine is still connected to the battery, so there is a greater chance of causing a short (or a fire) by dropping something that touches the positive terminal and just about anything else. To be on the safe side put back on the terminal cover that came with the battery when new.

The most consistent (and prehistoric) way I've found is to cover the +tive with a heavy sock whilst I work on it.

Simples !

[Byker28i]

mike_e said:

Make sure you keep the keys outside the vehicle or a door open when you reconnect the battery, the car will immediately lock itself once you hook up the battery.

Door open, boot open (where the fuses are) and of course bonnet open. Have the key fob ready for if the alarm goes off..

[FarmyardPants]

The main thing to remember if you remove the +ve terminal first is to make sure the spanner doesn't touch the chassis or engine while you're undoing the nut for the +ve terminal.

[tangerinedream]

Thanks chaps. I'll do the positive, but make sure I don't touch anything with the spanner and that nothing else touches the positive terminal. I happen to have half a tennis ball knocking about. That (or a big sock) should suffice.

[Juddder]

Revvit said:

Given the accessibility issues I've had a battery isolator/master switch installed. One turn and the battery is effectively disconnected without a spanner in sight. Not expensive to install and a handy addition in my eyes.

Any chance of a photo or link to the switch you used?

I've tried a number of the twist-to-disconnect battery adapters, but none of them fit under the scuttle correctly

Also have a battery brain sat in the box which I might now install seeing as I'm working on other bits of the engine!

[Revvit]

Revvit said:

I'll definitely not be wanting any petrol leaks

Given the number of other electrical components in the boot space it probably doesn't add much more of a risk, especially as I've had an auto electrician go other the entire car sorting out any gremlins.

Having said that, I am considering plumbing in an automatic extinguisher

Just arrived, great price too.



I'm sure that most engine bay fires are as a result of bad maintenance (or a lack of it), but as the car will be a keeper, I thought for the money it was worth it.

My only concern is how many red pull handles can one car have

Edited by Revvit on Saturday 2nd July 12:31

[gruffalo]

I would say three red handles would look good.

[Revvit]

gruffalo said:

I would say three red handles would look good.

Just don't pull the wrong one