On 11/06/2015 22:10, Cursitor Doom wrote:
Hi all,

A pal of mine is hosting one of the TT Zero teams for this year's
competition. This is a race for the newish category of zero-emission
electric bikes. They're developing very rapidly currently and are at
present capable of putting out 160bhp for 37.75 miles (one lap) at least
(on a good day anyway). Some online calculator I've tried states this is
equal to about 120kW but that seems like an awful lot to me and surely
cannot be right.

1 hp = ~750W, so that sounds about right.

What makes you think its unrealistic? With the right battery technology
you can suck amps out of them at a ferocious rate.

I was just wondering what sort of electric bill he can
expect (after they've gone home, obviously). They made several overnight
charge-ups during testing and he said his breakers were repeatedly
tripping out. Anyone care to do the maths? You'll have to allow for
efficiency as well, of course, since the 160bhp is the power OUT.

The power out tells you nothing much of any use directly. Ideally we
need to know the energy density of the battery pack for an accurate answer.

I'll
pass on the result when I see him again tomorrow (assuming it's not too
horrible, that is, as he has a heart condition).

ok a wild stab in the dark: (figures could be out by a significant margin!(

Well let's say the bike is competitive, and it can lap in 20 mins. If it
were running at full power for say 50% of the lap (don't know if these
things have any energy capture from regen breaking?) That would give a
total energy output of say 120 * 0.5 * 20/60 = ~20kWh

That would suggest a battery capacity of something in the order of 30kWh

(by comparison the latest Nissan Leaf boasts a 24kWh battery) - so that
may be a bit of an over estimate for something that fits into a bike
(unless it has a side car for the battery!).

Still 24kWh would equate to anything from five to ten quid a charge
depending on how efficient the charging process is.


--
Cheers,

John.

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