Battery position?
 

Hi guys and gals. Bearing in mind that I'm building a heavy-ish roadster type car with a dirty great iron block V6 up front my mind has turned to weight distribution. I've weighed the lump and 'box and even without clutch, flywheel, alternator, PAS pump, inlet manifold, ITBs, exhaust manifolds and fluids it still weighs an eye watering 182KGs, by the time all those bits n bobs are added its going to be resembling a rather ugly 1/5 Tonne if I'm not very careful. The motor is positioned as far back in the chassis as is reasonable but to try and counter all this weight up front I've been thinking about positioning some of the other heavy bits. To this end I have been thinking of using two six volt batteries in series and mounting them either side of the fuel tank. It will be easy to create access hatches in the rear deck and dedicated battery fixtures can be easily fabricated. electrically they can be connected via a key operated cutoff switch for safety (and security) which could even be mounted between the seats. So what do you think guys, is this a good idea or am I wasting effort?

D.

As long as you use heavy enough cable it should be fine. You might want to run a separate cable from each battery to the solonoid to compensate for the increased voltage drop of the longer run required.

Cable run shouldn't be a problem, MGBs, Jags and Beemers often had batteries under the rear seats or in the boot floor 25mmsq or bigger cable will do the job. Running a separate cable from each battery is a non starter as they will be 2 No 6 volt batteries so need to be in series, i.e. one battery's negative connected to earth and its positive connected to the negative of the other battery then the positive from that one connected to the starter solenoid. My biggest concern is the proximity of the two batteries to the fuel tank in the case of a rear end shunt. How would it be considered for motor sport scrutineering for example?

D.

No more comments, viewpoints, ideas?

D.

depending on what kind of eats you have you could put the batterys behind the seats but infornt of the bulkhead, 1 6V on ither side maybe depends on the seats i think i could just about manage that on mine, i dont think mr IVA man would be too keen on having the battry right next to the fuel tank though.

tilly

Bearing in mind quite a lot of people put a passenger foot rest in, what about between that and the bulkhead on the floor?

oh go on then... here,s my thoughts....:)

I,m not keen on the idea of the battery/ s being so close to the tank, i know other cars (production cars ) have had them in the rear, but .......

the back end of the 7 style car has very little protection of the tank area, so this is just IMHO i,d like to keep the 2 items , tank/battery apart from eachother to minimise the risk of the 2 items causing a problem to eachother.

Also, even tho you are using the mighty V6 motor, the position of the engine is quite far back in the chassis, look at how far back it is from the "axle line" of the front wheels, so having the battery mounted centrally in the car won,t adversley affect the weight balance of the car..... IMHO of course

cheers
andy

24v BOA's HATE low voltage output and struggle to start if the volts are low, any voltage drop could get annoyingly tedious.

May be worth looking at a decent MEGAMONEYWALLETSTRIPPING gel battery..

TT

Thanks for the input guys. I've had concerns about my idea with it putting the batteries so close to the tank myself (partly why I asked the forum really), the batteries could be placed in secure metal/wooden fixtures to keep them apart from the tank perhaps?

Passenger footwell? Not really much benefit there as it only lowers it not moves it back, it would lower the CofG though.

Volt drop? Really not an issue as long as heavy cables are used, I can easily get 35mmsq cable and would run both pos and neg to the engine bay to minimise points of potential (no pun intended) high resistance/voltage loss.

Behind the seats? I really don't think there is room for two 6 volt batteries there, I'm 6'2" so the driver's seat will be as far back as it goes to accomodate me.

I think TT's point about it not being necessary might be correct though, I've got the lump as far back as I can and it is well behind the front axle line. I'll have to weigh each corner to see what the distribution is like (I have some great portable weighing devices that can measure up to 100KGs per wheel) but I'll have to get the front suspenders done first.

Just kicking ideas around at the moment so I'm happy to hear other people's ideas.

Cheers, D.

Just thinking about it some more and maybe there would be room behind the seats if I made a boxed recess in each side...............

D.