big wattage motors draw amps whats the solution? bigger amps

[b0331e]

I have been informed that using a big motor say 750watts it will draw more AMPs from the battery, hence less range. So what would be the best set up to keep the range above 15 miles with hard throttle use and with the added !OFF ROAD! speed of 20mph+

"I know you ALL might be shouting get a 50cc moped, but the bike will be used for the following:- commuting, pedalling in the morning for fitness and getting home as quick as possible, with little or no use of the pedals"

For instance 500w 48v 15ah or 250w 36v 10/15ah or 350w 36v etc etc.
Common sense says I would need big AMP and VOLTAGE ratio as possible, to handle the BIG motor.

Or have I just answered the question myself.....


Finally a lot of people are saying that a 250w 36v 10ah set up will do 15 -20 miles on fairly flat ground with little or no pedalling is this the case.



B0331E

 

[Cyclezee]

Hi Bobbie,

This might sound obvious, big motor + big battery = big weight and the result would a bike is that hard to pedal without power.

 

[banbury frank]

Hi There is no such thing as a 500 watt motor

our Direct drive Brush less motors are suitable for 36 volts in to 72 volts in so 1,000 to 3,000 depending on controller and battery voltage

Gerard Motors are different as the will damage the gears with to much power


so its volts ( Battery ) X amps The size off the controller + the BMS off the Battery

A lot off battery's only have a maximum off 10 amps out some like the 48 volt battery's from BMS China are set at continuous 20 A peak for short time 40 A

48V 10Ah Li-Ion Alloy Shell EBike Battery Pack - BMSBATTERY


For longer range hey sell a 15 AH 48 volt battery but it is out off stock at the moment


This is the 1,000 48 volt kit to go with it

http://www.bmsbattery.com/ebike-kits/209-cute-1000watts-q-12-frontrear-driving--motor-e-bike-kit.html

They sell front and rear disc brake compatible


= Electrical watts the motor is about 80% good at turning that to power watts on the road

Hope this helps

Frank

 

[banbury frank]

Hi

Another thing to add I kept it separate or information overload

RPM per volt

Our motors and others like BMS Have different coil windings

So we do 5 or a 7

5 windings 12.5 revolution per minute per volt

We use this for high top speed but low climbing power but mainly when we fit into a 20 inch rim for folders

our normal kits use 7 windings so 9.5 RPM per volt Good Hill climbing And general use


SO volts say 48 v X diameter off Tyre in inches X 60 gives you inches per mile


convert inches into miles gives you miles per hour MPH



This is not a sales add as I do talk about other suppliers




Frank

 

[b0331e]

Cheers guys,
So what you are really saying in LAY MAN TERMS, will be that in order to have a high MPH without sacrificing on range I would need 48V 15ah battery with a big motor/hub wattage?
Also if I decide to cycle only (NO electrical assistance) it would be a great strain due to the weight of all the equiptment.
Would a 350w motor been ok with either a 36v or 48v battery?
Looks like I should stick to the standard 250w 36v 10/14ah setup ??

well thanks again

B0331e

 

[NRG]

If you want to go fast you need volts and a motor with a high speed wind for the wheel size you have.

Going faster requires more power so you need a motor with a high rated wattage so it won't destroy itself at high currents and sustained periods at speed.

To get high currents you need a suitably rated controller.

To power it all you need a battery with a good C rating to managed the high discharge current and to get range you need a battery with a high Ah.

Powerful motors add weight and the need for larger batteries adds more, this makes the bike more cumbersome to handle and manoeuvre and also makes it harder to pedal.

The Bafang BPM motor is well thought off and the 350w version will power you well above the legal limit....it's a good compromise between weight, power and battery requirements.

 

[b0331e]

Thanks to you too NRG, The only complete 350w on the market are the Alienbikes crew up in scotland, the Aurora and the Apollo, the Apollo being my first choice Electric Bicycles - Apollo £1,099. alas the 750w motor will draw amps from the 36v 16ah battery.

Do you know of any complete bikes closer to the UK!, or london rather(for warranty purposes, i would like the trader who I purchase the bike from to be within 50miles).

Otherwise it will have to be a conversion and there's only three traders I may go with, Cyclezee, Xipi or S.Larkins of Greenwhich london, do you know of any more Mr NRG

 

[banbury frank]

Hi

This might answer some off your Questions Battery 36 volt 15 AH

Hi Frank, below is the return journey from work on my converted mountain bike, I uses an iPhone app to capture the data. Overall very impressive nearly averaging 20 mph over 28 miles.
I have ordered a larger front chainring since I find I am spinning out on the downhills. The assistance I get from the motor is excellent, even against a head wind I was averaging 18 mph. The battery lasted the full journey and still had life left at the end, once I gauge the limitations of the battery I will use the motor a bit more giving me better results. I peddled as I normally would probably about 200 watts, as I said earlier I still want to ride my bike as a bike and use the motor to assist and bail me out when I get the dreaded knee pain.
Overall result very impressive and a talking point amongst my workmates. You can see the actual route if you click on the blue link .... View on Map
I will contact you soon to return the controller to add the brake regen wires.
Thanks

Pat

Sent from my iPad


Date: 13 June 2011 10:28:12 GMT+01:00
To: "Caffrey, Pat"
Subject: MotionX-GPS Track: Track 006

Hello,

Pat uses MotionX-GPS on the iPhone and is sharing with you the following track:

Name: Track 006
Date: 13 Jun 2011 8:51 am
Map:
(valid until Dec 10, 2011) View on Map
Distance: 28.2 miles
Elapsed Time: 1:26:14
Avg Speed: 19.6 mph
Max Speed: 28.1 mph
Avg Pace: 03' 04" per mile
Min Altitude: 119 ft
Max Altitude: 614 ft
Start Time: 2011-06-13T07:51:22Z
Start Location:
Latitude: 55.103634º N
Longitude: 1.598218º W
End Location:
Latitude: 55.403013º N
Longitude: 1.707127º W


Frank

 

[b0331e]

Thanks Frank.

Information slightly useful! I spoke to your brother the other day, also looked at your website and ebay pages, alas the pricing of what you have on offer has confused me. So can you PM if you have a complete bike for £1000 mark or a kit + fitting + my own bike (TREK 7300fx 2004/5) for the same money please? Bearing in mind either must meet some if not all of my requirements..........


B0331e

 

[banbury frank]

Hi

b0331e

Can you please Email me at

frank@xipi.co.uk

Then I can respond as I don't monitor my pm box on the forum

Frank