# Electric car



## Ziggythewiz (May 16, 2010)

So...is this a car, or a bike?

What is the intended use?

70 mph can be scary in a VW bug, on a bike?? And rather uncomfortable for 75 miles at a stretch.

Typical e-bikes run from 24-48V, 144 seems a bit much.


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## Iain (May 15, 2012)

Hello, yes this is for an electric bike, wasnt sure if 70 was a safe idea or not, or even if the pack could be sized for such a job 

so [email protected] 250A peak for a 6kw pack, (100 kg?) which seems way to heavy 

maybe an electric motorbike would be a better idea with stronger frame and aero parts? 

thanks 

Iain


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## frodus (Apr 12, 2008)

do you mean 125Ah and 6kwh?

150 miles is going to require a HUGE pack. rethink your range requirements, or increase your budget and get a very large bike.


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## njloof (Nov 21, 2011)

Or pedal. You can easily stretch the range of an electric bike by using a food-based energy source.


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## Ziggythewiz (May 16, 2010)

Not at 70 mph...


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## Iain (May 15, 2012)

LOL peddling at 70... Id love to see that..

ok yes, 50 miles range is better I think at 50-70 mph you guys think? 
a 2.5 kw pack, or more pertinently: what is the largest size pack I could get away with 

thanks

Iain


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## njloof (Nov 21, 2011)

I'll be honest, I have a beefy chopper bicycle carrying about 1kW of lithium and it's a good chunk of weight to stabilize. Hang it off the top tube and your stability will suffer. I put mine just in front of the cranks.

Some folks build custom packs in triangles made to fit the frame, but I've never seen a 2.5kW one. Pick a battery and start looking at the geometry issues...


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## frodus (Apr 12, 2008)

Iain said:


> LOL peddling at 70... Id love to see that..
> 
> ok yes, 50 miles range is better I think at 50-70 mph you guys think?
> a 2.5 kw pack, or more pertinently: what is the largest size pack I could get away with
> ...


You won't be able to do that on a bicycle. And I wouldn't try, at those speeds, it's dangerous not only to you, but others on the road. 

To be possible, you could go 50-70mph on a motorcycle, you're going to be using between 100 and 130wh/mile, so you'd need at least 5kwh, but it could need to be up to 6.5kwh, but you want a bit over that because you don't want to discharge to 100%, so maybe 5.5-7kwh. There's no way you'd get 50 miles range with 2.5kwh of battery. And you'd almost 100% have to go with lithium. 

Above 5kwh the pack gets harder and harder to fit into a normal 600-700cc sized motorcycle.

And that motor might have trouble hitting 70mph. 48V is a bit low for a motorcycle. Start thinking 72-96V.

Also, try to use the correct units. You're speaking about energy (how many kilowatt hours) but using units for power (kw).


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## mizlplix (May 1, 2011)

Reverse engineer this one.

What speed would you feel safe stopping from with those brakes?

Some early motorcycles (motorbikes) looked similar to a mountain bike, but they had some suspension and better brakes.

They only went 35mph or so too...

Miz


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