Been having a good look at my chassis, and it seems to me there is no reason I can see why I shouldnt make a battery tray in the back over the diff mounting area, and even form a boot box over it (so the battery is in the boot but supported by the chassis)

Seems like a good way of moving a bit of weight from the from to the back, I know it won't make much difference but is a step in the right direction?

No reason not to, but don't go too small on the battery or cable as the starter pulls a lot of current down the now longer wires.

If you're planning one of the lightweight racing batteries it's not worth it IMO.

It puts a heavy item high up and very far back. Be better in the middle and low, passenger
footwell for example. Unless you are using a bike battery.

Try to keep the battery within the wheelbase, and low down.

I wouldn't think it will make a great deal of difference, but would think twice about putting a battery next to the fuel tank.
Paul

got mine in back , much better for setup,

I would only do that if you do not have space in the engine bay or passenger footwell.

You will need to have thicker cables if you do not want problems starting the engine.

Apart from that, it is ok, apart from the extra cable length and cost.

Better of using a smaller gel battery instead of the bulky Pb-acid.

You want a larger cross sectional area cable to take the maximum starting current to avoid a fire, let alone starting problems.

Get tri-rated cable from your local electrical wholesalers. You need to work out how big, but the current you need it to carry.

some interesting thoughts thanks, about the height, most people put it on the shelf in front of the scuttle, thing is, that is higher than putting it above the diff on independant cars.

I knew about the extra rating needed on the cable but its always worth mentioning these things in case I didnt, thanks

Mine's an MX5, so it's already in the boot. Best place for it, IMO, it's nice and tidy in there and dead confusing for Mr. AA Man

FWIW, the batteries used in NA and NB MX5s (mk1 and mk2) are smaller than standard batteries and a little lighter in weight. Maybe worth a look? (WestCo are the common battery "upgrade", and would probably be a good place to start.)

As for weight reduction, I'm not sure you'll be gaining much - the extra length of the extra gauge cables will see to that. However, if your car is currently front-heavy, this may well be a good step to take. Just make sure to fit it as far forward as you can.

Chris

[Edited on 26/7/2010 by iti_uk]

It really depends what engine you're installing and how the weight will be distributed anyway - my Indy was 60% to the rear with an R1 engine in, so if I was going to move the battery anywhere, it would have been further forward and lower down (just behind the steering rack probably).

Mines in the passenger footwell on the floor, short cable to the starter and was thinking of putting a heater above the diff!

the previous owner of my car put it at the back. I think it does look neater and cuts down the wires in the engine bay. The weight offset I think is probably very small.

Its really up to you. If you think its worth your time and money then do it. Nobody will tell you its wrong.