E30 Zone

my 2 door 1990 325 has the battery in the boot does anyone no why?i thought it was to do with weight distribution any ideas?

There's no room for it under the bonnet?

beemerbird wrote:There's no room for it under the bonnet?

there is room on the offside inner wing for it, as the battery tray area is there but vacant.

Someone has probably done a conversion then. My 325 has it in the boot, and I assumed it was standard.

mine does to, its pretty weird

It is the standard location for 325i coupe i believe. Helps with balance of the car for handling shifting some of that heavy weight into the rear of the car.

Yep, Euge is spot on. Only on 325's> as far as I know but kits can be bought for other models.

mines not a coupe, shorley it cant be for weight distrapution, how can a battery make much of a difference to weight distrabution its not a racing car its just like a luxury car.

It may be, then, that a fully spec'd 325 (AC, headlight wash / wipe, all the baubles etc etc) would not leave enough room in the engine bay for the battery, so as standard the battery was relocated to the boot. This is purely guess work on my part, however

iceox wrote:mines not a coupe, shorley it cant be for weight distrapution, how can a battery make much of a difference to weight distrabution its not a racing car its just like a luxury car.

Have you weighed a car battery? They are not light. Porsche "cured" the dreadful lift off oversteer of the first run, short-wheelbase 911s by adding 20 odd kgs to the front of the car in the form of 2 weight-plates. The "battery in the boot" is a definite must have to offset the weight of the six cylinder engine when compared to the beautiful weight distribution of the 4 cylinder cars.

It is incredible how, not so much the weight, but position of an object makes a difference in a car. The battery tray is by the firewall normall, hence within the wheelbase, but the tray in the boot is behind the rear axle. This shift of location makes an incredible difference, many times the weight of the battery. For instance, If I fill my petrol tank, the car does not sink much on the rear axle as the load is before the axle. If I fill my LPG tank, in the spare wheel tray, the thing sinks like a stone.

Just my 2 cents, though persoanally it seems a rather strange mod - and alot of cable.

Yes, standard on all 325i models apart from the Touring, which has it in the normal place up front.

iceox wrote:mines not a coupe, shorley it cant be for weight distrapution, how can a battery make much of a difference to weight distrabution its not a racing car its just like a luxury car.

I was told it was moved to the back due to weight distribution.

As Tesco says, 'Every little helps'

Speedtouch wrote:Yes, standard on all 325i models apart from the Touring, which has it in the normal place up front.

touring and cabby were the only ones that did not have the battery in the boot all 325s either 2 door or 4 door and the m3s all had the battery in the boot ( i think the diesel had the battery in the boot as well but cant remember to be sure .. ) the touring and cabby had the battery as Speedtouch says up front in the normal place

Yep all the 325s i have seen have it in the boot. However i have stripped it all out of mine and fitted the smallest battery i could get my hands on and it is now on the original tray.

Have saved much weight and it has enabled me to run much softer springs on the rear as i run with no spare wheel or back seats

This is a rally car so overall weight is very important, not least for stopping the sucker. Balance is very good with this set up as you can easily transfer weight to the rear using the throttle.

Funny to read that your suprised BMW would move a battery to distribute the weight of the car evenly between the axles. BMW has to have some tricks up their sleeves to be the best.

If that is a shocker, then all you convertible owners go check the same rear right corner and you'll find a 22 kg weight plate suspended onto the body. This is supposedly to avoid chassis vibrations. On wonder a convertibles are much heavier.

I have heard the above reasons, but also heard it was partly due to the excess heat generated by a B25/ S14.

I can't imagine why

Andy

johnlouis wrote:It is incredible how, not so much the weight, but position of an object makes a difference in a car. The battery tray is by the firewall normall, hence within the wheelbase, but the tray in the boot is behind the rear axle. This shift of location makes an incredible difference, many times the weight of the battery. For instance, If I fill my petrol tank, the car does not sink much on the rear axle as the load is before the axle. If I fill my LPG tank, in the spare wheel tray, the thing sinks like a stone.

Just my 2 cents, though persoanally it seems a rather strange mod - and alot of cable.

Regarding the sinking. It's all dependant upon the pivot points. The lpg tank although the weight must be lower, when calculated using moments, F=W1D1 as compared to F=W2D2. Even thought the value of W1 may be greater than W2, the D1 and D2 make an incredible difference.

In simple words, the car will get a boner.

H35-24 wrote:Funny to read that your suprised BMW would move a battery to distribute the weight of the car evenly between the axles. BMW has to have some tricks up their sleeves to be the best.

If that is a shocker, then all you convertible owners go check the same rear right corner and you'll find a 22 kg weight plate suspended onto the body. This is supposedly to avoid chassis vibrations. On wonder a convertibles are much heavier.

I was told they're much heavier because although the roof is chopped off, to make the body more rigid and stable they added extra thick "beams" or whatever running through the length of the sides of the car to prevent warping or something.


Just what I've been told by a mate, not sure if it's true or not, may be may not be, I have no idea.

I good suggestion though?

H35-24 wrote:Funny to read that your suprised BMW would move a battery to distribute the weight of the car evenly between the axles. BMW has to have some tricks up their sleeves to be the best.

If that is a shocker, then all you convertible owners go check the same rear right corner and you'll find a 22 kg weight plate suspended onto the body. This is supposedly to avoid chassis vibrations. On wonder a convertibles are much heavier.

I wondered what that was in the boot.

According to Jeremy Walton in his BMW 3 series book,

The battery was located in the boot because BMW decided to uprate the capacity of the battery from the standard 320i's 50 amp hour rating to 66Ah, plus an 80Ah alternator kicking out 1120 watts. (So presumably the larger battery would not fit in the engine bay well). The slight loss in luggage capacity was compensated by a slightly better redistribution of the considerable kerb weight.

I had also heard from someone else that it was to comply with German law at the time of production which required BMW to take some steps to try to sort out the tendancy of the back end to step out. This was the answer they came up with which seemed to satisfy the relevant authorities.

E30Gheko wrote:I had also heard from someone else that it was to comply with German law at the time of production which required BMW to take some steps to try to sort out the tendancy of the back end to step out. This was the answer they came up with which seemed to satisfy the relevant authorities.

Hmm, a large heavy weight placed outside of the axles - you would think that would have a pendulum effect, negating any advantage to be gained by adding weight over the back tyres...

Hmm, a large heavy weight placed outside of the axles - you would think that would have a pendulum effect, negating any advantage to be gained by adding weight over the back tyres...

That's a good point, the first answer to me sounds a bit more logical and comes from a well regarded source.

I can live with that Also, there is something vaguely exotic/sporting having it in the boot

I can live with that Also, there is something vaguely exotic/sporting having it in the boot

Also been incredibly handy when I've had to jump start a few of my mates cars. You can just reverse up which is far safer on a busy road!!

Yes, good point, it is handy for access. Unlike a VW Beetle and MGB GT I had, which had it under the back seat. The VW Beetle suffered a common fault where the seat springs would short the battery out - one poor owner discovered this while driving down the street with his kids bouncing up and down on the back seat