Electrified Downhill bike - Page 4 - RC-Monster Forums

Metallover · 04.30.2010, 09:28 PM

You might find this interesting. Built by recumpence, also the maker of this.

A Bugatti has a power/weight ratio of 4.2lbs/hp.

This e-bike has 14 Horsepower and it weighs >50lbs. It has close to 3lbs/horsepower. That is only beaten by the fastest superbikes and indy cars.

http://endless-sphere.com/forums/vie...hp?f=28&t=9534

Video
http://www.youtube.com/watch?v=DtcTY...layer_embedded
[youtube]DtcTYmI5tfA[/youtube]

zeropointbug · 04.30.2010, 10:54 PM

That is what I'm talking about! 14hp is what I want in my ebike (not this one I will build for my brother), but in mountain bike form. So what motors are being used? Brushed?

Actually, to be fair this thing has a power to weight of more like 16lb/HP if you actually have someone riding it!

Hey, that gives me an idea, R/C controlled ebike!

Metallover · 04.30.2010, 11:23 PM

He's using two Astro 3210 brushless motors Astro makes them for ebikes by request. He's using CC HV110 controllers and lipos too. Check out the second page of the thread for pics. The first 4-5 pages are worth a glance.

zeropointbug · 02:32 PM

That's cool. How much are the Astro motors? What controller would he have used? .......NVM, I searched and found it: $400 not bad!

http://cgi.ebay.com/A123-cell-2300ma...item2a066e4733

I am wondering if these are a good buy? They are obviously genuine A123's, and they are a decent(ish) $8/cell, which I wouldn't mind paying the extra bit if I know what I am getting. I keep thinking $400 is alot for a battery for it, but then I remember that if you would buy a purpose built ebike battery, you are looking to pay $500-$600 for the same range, and then the cells they are no match for an A123 based pack... very inexpensive in the long run.

At least 2000 cycles @100% DOD x 20 miles range = 40,000miles/65,000km Then even after this point, the pack would most likely still be around 80% capacity, still perfectly usable IMO. $400/40,000miles = 1 cent per mile of battery cost over the life time.

zeropointbug · 05.01.2010, 11:24 PM

Metallover, could you tell me what your ebike consumes in Wh/mile? What speed, and whether you pedal or not?

PBO · 05.02.2010, 01:40 AM

Quote:

Originally Posted by zeropointbug

That's cool. How much are the Astro motors? What controller would he have used? .......NVM, I searched and found it: $400 not bad!

To me they look like the 3220 motor?

zeropointbug · 05.02.2010, 03:13 AM

Could be either motor really? Looks like they have good idle current too, good for an ebike for sure... now if someone could throw that in a hub with a planetary gear drive, you are flyin!

Metallover, okay thanks for the info, but how fast are you cruising at when you get 40Wh/mile?

This is for my brother, who says he doesn't need to go that fast, 40km/h (25mph) is fast enough, which I think is the top speed of the Nine Continents kit at ~36V, no?

I asked Cell_man at Endless-Sphere about the 15Ah cells, so a 12s pack should be 550Wh and at ~16Wh/mile that I am seeing kit suppliers say a bike will do at 35-40km/h, should be a good 30+ miles range. The large pismatic A123's are a good price of $2.5/Ah, or $38/15Ah cell,

Have you ever tested at various speeds and recorded the Wh/mile, say, in 5 km increments?

Metallover · 05.02.2010, 12:18 AM

Here is all of the data you would ever want to know about my bike
http://spreadsheets0.google.com/ccc?...A26RsYfg&hl=en

I get about 40wh/mi when I don't pedal much and drive like I stole it. I have gotten under 25wh/mi before, with lots of pedaling, and if I can get this controller modded I will lower the amp limit from 20a to 10a which should get me 25.5wh.mi without pedaling.

I'll also be able to remove the amp limit for twice the power.

Here's some AWESOME e-bike prediction software. It's worth the trouble of downloading it.
http://www.endless-sphere.com/forums...119810#p119810

Currently the bike can do 35mph pretty regularly. I've gotten to 38mph on a long flat and 39.5mph down a hill. This is with the 20a limit; raising the limit won't help my top speed tho.. With a 10a limit it will decrease my top speed to around 25mph.

On long rides I pedal as much as I can. I can get 15mi not pedaling and going full out all the time, so when I stay in town I usually don't pedal.

bumsnogger · 05.02.2010, 09:24 AM

Hi guys,The chain drive is a better idea,especially on an mtb with suspension.You need the weight suspended.If its hub mounted it makes it hard to do much,the wheels drop as soon as you get any air under them,making the bike handle awfully.

PBO · 05.02.2010, 07:28 PM

Quote:

Originally Posted by bumsnogger

Hi guys,The chain drive is a better idea,especially on an mtb with suspension.You need the weight suspended.If its hub mounted it makes it hard to do much,the wheels drop as soon as you get any air under them,making the bike handle awfully.

You're right but most who use the hub drive do it to keep the CoG down

zeropointbug · 05.02.2010, 11:58 PM

That's true. and quietness.

Metallover · 05.02.2010, 11:21 AM

Wheelies rock with a rear hub?

When I get 40wh/mi I am usually crusing at... 30-35mph.

My general guideline is that if you keep the average non-geared hubmotor e-bike to 25mph you should get around 25wh/mi without pedaling.

I don't know how fast it would go at 36v.. I got around max 25mph on 44.4v lipo with a 26" rim. Pedaling would probably get you to 25mph on 36v with the 9c, but you would be looking at about 20mph w/o pedaling.

Play around with that e-bike prediction software some and you'll see some better numbers.

zeropointbug · 05.02.2010, 03:46 PM

Okay, are you using the "fast" version or the regular version hub motor? THe fast version uses the 2806 motor instead of the 2807. But I think I would rather get the 2807 and run a higher voltage of 48V.

bumsnogger, yeah I would have to agree with you one that, if a good belt drive or something could be made I would much rather have external drive than hub driven. Suspension would feel like garbage for sure, unsprung weight is very critical in a good handling vehicle, be it car or bike.

Metallover · 05.02.2010, 05:39 PM

I've got the 2807, aka 9x7, aka the slow one. Plug the fast one into the ebike prediction software and see what you get.. I think the fast motor is made more for people who want to run 36v.

zeropointbug · 05.02.2010, 06:10 PM

Yeah, and the 2806 26" kit I think gets to 25mph on 36V? Is that right? I have having a hard time finding much info on speeds for the different kits.

I am thinking about the fast version as it would allow the bike to hit 30mph maybe on 44Volts (14s 15Ah A123 prismatic), and still have enought range to make it useful.