Lightweight batteries?
Discussion
In the awesome S1 Exige rebuild thread on SELOC (George in NZ rebuilding an S1 Exige from ground up - well worth reading as it's incredible, awe-inspiring stuff), he mentions that instead of saving 6.5 kg by installing an aluminium fuel tank, he was going to save 6.5 kg later by swapping the standard battery for a 'lightweight battery'.
What's the deal with this? I know that normal batteries weigh a lot, and I'm assuming that Lotus stayed cheap and reliable by using a normal battery like the ones available in Halfords (lead acid). I'm assuming there's a typical battery in the back of my Exige too (otherwise it wouldn't start very easily). Now these batteries are usually 10-15 kg, right? Probably nearer 15 kg (does anyone know the exact weight?)
Saving 6.5 kg by changing a battery sounds like an impressive reduction that's very easy to do, no? So why isn't it a very common suggestion on the forums for those wishing to reduce weight without compromising comfort? Are the 'lightweight batteries' much lower capacity and less functional? Lead-acid is a pretty old, well-proven technology but I'd guess a decent lithium ion battery could provide the same capacity and rechargeability at a much lower weight. I know the raceboys use Varley (sp?) red top batteries, not sure what technology they use but they are purportedly much lower weight, but also lower capacity IIRC.
Another issue in the boot of an Exige is the actual space taken up by the battery - it's not an insignificant proportion of the boot volume in my car, and a new technology battery that was half the size would add a boot space benefit as well as a weight benefit.
So what are these lightweight batteries - are they a practical, direct-replacement option to lose some weight and add some boot space? Automotive use of lithium batteries is surely fairly mainstream now there are loads of Toyota hybrid 'vehicles' around...
What's the deal with this? I know that normal batteries weigh a lot, and I'm assuming that Lotus stayed cheap and reliable by using a normal battery like the ones available in Halfords (lead acid). I'm assuming there's a typical battery in the back of my Exige too (otherwise it wouldn't start very easily). Now these batteries are usually 10-15 kg, right? Probably nearer 15 kg (does anyone know the exact weight?)
Saving 6.5 kg by changing a battery sounds like an impressive reduction that's very easy to do, no? So why isn't it a very common suggestion on the forums for those wishing to reduce weight without compromising comfort? Are the 'lightweight batteries' much lower capacity and less functional? Lead-acid is a pretty old, well-proven technology but I'd guess a decent lithium ion battery could provide the same capacity and rechargeability at a much lower weight. I know the raceboys use Varley (sp?) red top batteries, not sure what technology they use but they are purportedly much lower weight, but also lower capacity IIRC.
Another issue in the boot of an Exige is the actual space taken up by the battery - it's not an insignificant proportion of the boot volume in my car, and a new technology battery that was half the size would add a boot space benefit as well as a weight benefit.
So what are these lightweight batteries - are they a practical, direct-replacement option to lose some weight and add some boot space? Automotive use of lithium batteries is surely fairly mainstream now there are loads of Toyota hybrid 'vehicles' around...
Heh - that's excellent. I have had the 'pleasure' of replacing the battery in my old VX220 turbo (in the front, under all the loom, like the S1)... took myself *and* an AA mechanic an hour in the pissing rain. He wasn't best impressed with the car at the end of the job, I ended up giving him a big tip to buy some beers that evening as we both ended up with badly cut knuckles and fingers...
I've got the Touring pack on my Exige and it's got a bunch of electrical toys, though I don't do stereo systems in Lotuses so no amplifiers or any other large-current devices. The aircon is pneumatic, isn't it - draws crank power but not electrical (glad to be corrected on this). I guess the biggest problem would be lights when the engine is off... once the engine is running, the alternator ought to supply enough electricity to cope with most things.
That said, I don't live in as nice a climate as you, and I don't own a garage, and I'm not best known for 'pampering' cars... so starting the car when subzero is a regular occurrence (and has been over the last two weeks)... whether the tiny race battery would deal with that, I don't know. I know the Exige only has a baby engine but 18 Ah is a lot less capacity than the typical 60 Ah.
Anyway, I've just come back from a great trackday at Brands and it's utterly clear that I don't need any modifications, the car is plenty capable enough as it is - just upgrade the nut behind the wheel and all will be good
Thanks for replying George in typical thorough fashion - you are doing one hell of a job on your car and hopefully it'll inspire others to keep these cool S1 Exiges on the road and track. It's going to be awesome and, crucially, stay that way for a long time (that POR15 stuff looks the nuts...)
I've got the Touring pack on my Exige and it's got a bunch of electrical toys, though I don't do stereo systems in Lotuses so no amplifiers or any other large-current devices. The aircon is pneumatic, isn't it - draws crank power but not electrical (glad to be corrected on this). I guess the biggest problem would be lights when the engine is off... once the engine is running, the alternator ought to supply enough electricity to cope with most things.
That said, I don't live in as nice a climate as you, and I don't own a garage, and I'm not best known for 'pampering' cars... so starting the car when subzero is a regular occurrence (and has been over the last two weeks)... whether the tiny race battery would deal with that, I don't know. I know the Exige only has a baby engine but 18 Ah is a lot less capacity than the typical 60 Ah.
Anyway, I've just come back from a great trackday at Brands and it's utterly clear that I don't need any modifications, the car is plenty capable enough as it is - just upgrade the nut behind the wheel and all will be good
Thanks for replying George in typical thorough fashion - you are doing one hell of a job on your car and hopefully it'll inspire others to keep these cool S1 Exiges on the road and track. It's going to be awesome and, crucially, stay that way for a long time (that POR15 stuff looks the nuts...)
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