Dave Wellings on Safety Items with Rear Mounted Batteries

Dave Wellings on Safety Items with Rear Mounted Batteries

This week a MogTalker had his Roadster catch fire when the battery live cable chafed against the battery retaining bracket and shorted out.

The fire was fortunately brought under control quickly and the damage appears from photos to be repairable, although the seat backs look a mess.

There are varying views on where a battery is best located. Under the rear panel is a traditional place to put the battery.

MG put them there from a very early period.

Twin sixes fit nicely either side of the prop shaft and can be fitted low down, so weight distribution and Centre of Gravity are both covered well.

Furthermore that position keeps the battery cool - but accessibility is poor, and there is a long cable run to the engine.

On the bulkhead - the battery is set high, and on the drivers side for right hand drive.

Having a weighty item high up is not good for the centre of gravity, and having a container full of acid over ones legs is not ideal.

The battery also gets subjected to engine heat, but is easy to get at and has short cable runs.

If your battery is in the back, you need to check the cables, to make sure there is no chafing.

I did mine this morning.

First pic is the new jack and lifting board. Note the sleepers under the rear wheels.

This is the right side looking forward and shows the earth cable connection to the battery.

The cable curves under the carrier and locates on the left side lower bracket.

It doesn't matter really if this cable chafes, because it's to earth anyway.

I've included this one to show how hard it is to see anything from below.

Obviously you can take the tool tray out and remove the alloy flap behind the nearside seat to see more.

But the camera can get where no man has gone before.........

You can see here that there are two red live cables.

You can also see what I think is a master fuse, I've not yet had this apart for a look.

Any short downstream of the master fuse will blow the fuse, so it's only a risk on the short length of wire between battery and fuse.

The thin wires are the adaptor for the battery conditioner, which pass through the wooden bulkhead in a grommeted hole just to the left of the wingnut.

The big red cables are tied out of the way with a red cable tie, and I suspect that I did this when I fitted the neoprene liner to the ally cover plate.

You can see here the relationship between all the fittings.

Note that the battery has twin terminals - two positive and two earth, so that it can fit multiple applications.

Note also that the live cables cross over the car in the black wrapped cable high up.

This is not the cable visible in the previous two shots, that's the handbrake cable.

Note to self: The battery needs a clean.......

This is where it sneaks inside the car.

Handbrake cable at the top, live cables below.

This is adjacent to the offside leaf spring front mounting.

The cable then runs inside the cockpit under the offside trim panel.

It emerges here.

This stud is under the dash in the top right hand corner.

From here the power is fed to the fuse boxes.

2017 note: I later added a fuse to the battery charger positive cable.

Note that this is a 2005 Morgan and things have evolved both in terms of where the fuse boxes are, where the relays are, and where the master fuse is.

In 2012 the master fuse was under the dash. Currently most of the Traditional electrics are in a sealed box on the bulkhead.