Battery Vehicle Society

Thanks for the offer, Howard, but I'm already well into building my Yamaha conversion.

Jeremy

EVguru wrote:..................Good grief, we'll make as little progess by never dissagreeing as we will if we never agree.

I'm sorry if my tone comes over poorly sometimes, but as I've stated many many times, I find writing a very difficult process, which is why you're unlikely to get many articles for 'Plugged In' out of me.

Thanks for adding that bit Paul

As Paul says we wont make progress if we all lived in a lovey dovey world would we,BUT sometimes plain text can come over as agressive as we dont see the other persons expression and dont forget when you are face to face with someone we can get 75% of the meaning of something via facial expressions, so can we all remember what we are posting and what someone else may read it

Right moving on ........... sounds interesting all this

ChrisB

This caught my eye at the bike show last year.

www.megelli.com

Their 125r was a fabulous looking machine and quite light at 110Kg

I spoke to their sales guy and he was quite interested in the idea of doing an electric version, but at the time they were bust just getting the 's' model into production.

Jeremy
My bike (unfaired, 130 kg + 65 kg) uses around 5 kW at a steady 50 mph on the flat. That seems to compare well with your 1 kW at 30 mph, just looking at air resistance.
i.e. (5/3) cubed * 1 kW = just under 5 kW.


Totally agree about this not being a perfect medium. Need more meetings and a central venue where we can all meet up once in a while...

MalcolmB wrote:
Totally agree about this not being a perfect medium. Need more meetings and a central venue where we can all meet up once in a while...

Why not give Skype a try? It's free and works pretty well www.Skype.com Could also use YouTube too

Yes I've had a Skype account for a couple of years ... and used it about three times just to keep it active. It might work for some people, but for me nowt beats real life meetings

MalcolmB wrote:Yes I've had a Skype account for a couple of years ... and used it about three times just to keep it active. It might work for some people, but for me nowt beats real life meetings

I too agree but with petrol well over £1 a litre and with people scattered over the country such as you in Newcastle and me in Dorset it gets expensive and a lot of good communications can be done by other means. I do it all the time with people scattered all over the country and indeed abroad too but yes there are good reasons to get together and meet up too.

I know that John Lilly is rather keen on the idea of the TT as is Frank Wykes so perhaps meeting at a BVS committee meeting may be a good idea?

Many thanks for that, Malcolm, it's comforting when pure hypothesis gets confirmed by a real world data point! My guess is the rolling resistance for your bike might be very slightly higher than for my lightweight machine, so if anything my present model probably errs on the side of being slightly pessimistic, which is a good thing.

I can press on and try to model the power/weight/speed trade-offs a bit better now. I'm still thinking along the lines of a very light bike as the answer, primarily because the acceleration and hill climbing power requirements are significantly reduced. It'll need a regen controller, for sure, as the 5% to 8% power recovery that might give will reduce the required battery weight by a useful amount.

I doubt that traction and ultimate road holding will be an issue, so there may well be some benefit in going for narrow tyres, to reduce rolling resistance and also reduce the rotational mass of the wheels (which will save power when accelerating).

I suspect that LiPo batteries will be needed for the lightest possible power source, provided that the safety regulations don't rule against them. An acquaintance is using a big Kokam LiPo pack in an experimental electric aeroplane and hasn't had any problems yet, which is reassuring. He's pulling a steady 8 to 10kW from his lightweight battery pack, with a peak of around 12 to 14kW I believe, which is probably close to the requirement for a small IoM racer.

Jeremy

How light were you thinking Jeremy? The Megelli that Paul linked to looks good, and being a new British company they may be interested in donating a machine without engine if a well-conceived proposal were put together on behalf of the BVS.

It might be possible to do the same with motor, controller and batteries.

I doubt that traction and ultimate road holding will be an issue, so there may well be some benefit in going for narrow tyres, to reduce rolling resistance and also reduce the rotational mass of the wheels (which will save power when accelerating).

Narrow tyres will probably not be available in high enough speed and load ratings and there really isn't such an animal as a low rolling resistance motorcycle tyre.

When I was helping with the Porsche in the US, everybody was running a standard size or narrower LRR tyre at maximum pressure (or above!). Looking at lap times and throttle maps, we decided to change our 185/70-15 tyres for 225/50-15 road legal race tyres (Hoosiers) at the same time as we upgraded our suspension. The difference was dramatic, both lap times AND energy consumption fell. The ability to carry much more speed through corners reduced the need for acceleration.

Rolling resistance is more or less a constant based on weight, not speed. You gain most benefit where it's influence is highest; at low speed around town. At higher speed air drag dominates and you don't see the effects of lower rolling resistance.

It'll need a regen controller, for sure, as the 5% to 8% power recovery that might give will reduce the required battery weight by a useful amount.

Backing off the throttle earlier to control speed saves more energy than you'll recover under braking. Regen should be used with extreme caution. I've seen two crashes in racing due to its use. Locking the rear wheel on a motor cycle (an effective lockup, since it HAS to rotate to generate) can be disasterous and some race schools teach you not to use it at all.