Hi from Anglesey North Wales

[GT3]

To help from my experience;

I have a 36V 20Ah Ping mounted on the rear rack. It is difficult to handle from the side, but I don't notice it under way and have no traction problems with a front motor. It got me home when the roads were covered in ice and snow, although that would have had more to do with the Marathon Winter tyres.

My round trip is 32 miles and I regularly do 8 or 10 more. I've only run the pack flat once, at 48 miles. Range is entirely dependant upon use, I'm 16 stone+ with plenty of hills to climb. Using a 350W motor I average 18 odd mph. To travel at 30, you'll need a fast turning motor and plenty more power! Ideally I will move to frame mounted bottles, but am a little wary of the reduced capacity.

Hope that helps, I do like your home, I've had a weekend in the Cymyran for the last few years, driving the circuit - great facility.

 

[Quark]

Hi thanks for the advice, I'm initially looking to run 48v 15ah, I'm not sure if I will get enough range from this but its a good place to start, I would love to run 72v 20ah eventually but I need a frame that can store the batteries much lower, this is why I'm toying with the idea of building my own bespoke frame designed to accommodate all the power I need.

 

[Deleted member 4366]

Hi All,
Thanks for the warm welcome, although Im loathed to mount the battery in the rear so high up, with the bike frame I have there isnt very much room in the triangle, I have done a few tests with 15kg in the top box and it does feel a little top heavy but not unmanageable, i may have to drop to 15ahr or even 10ahr if the weight is really an issue, I may give it a few more tries with different weights. The bike will be pure throttle with no need to pedal but I still intend to pedal to help keep fit, the motor and controller are both capable of much more than I intend to use, but with a basic setup drawing around 30 - 40A continuous with potential 80A bursts of power it is likely it will be capable of speeds up 30 - 40mph but because of range I will limit this power and speed using the programmable controller and cycle anylyst, I realise this has legal implications but I have decided to try my luck with the law as I dont agree with the limits for electric bikes anyway. I like the sound of these water bottle batteries, what kind of output are they capable of? I was thinking of going down the 15ahr lifepo4 headway cells route, as I can easy add to the pack when budget and frame size increase! Hi to wissy im in Llangefni and need to ride to RAF Valley! Just need to figure out how to post some pics now!

When you test-ride with equivalent weight in the box, you don't get the torque effect from the motor, which unloads the front tyre and makes it slip. Torque is always difficult to control because you get maximum torque at low speed, so you have to be very careful. 80 amps will flip your bike pretty quickly with a heavy motor in the rear wheel and battery in a top box. I tried 40 amps and that was scary enough. You should have a look at the various threads on Endless sphere about taming the throttle, and consider using current control rather than speed control for which you need a CA or Speedict or similar. You'll see what the problem is as soon as you start riding the bike - and fall off a few times.

 

[Quark]

Yes it will be trial and error for the first build, I have a CA and a fully programmable controller so I will be able to tame the power to suit, plus I wont be able to use full power if I expect any kind of useable range from the limited battery capacity I can carry, your vision of me flipping over the back of the bike or constantly loosing the front end and crashing may well be a little over exaggerated! However we will see!

 

[Deleted member 4366]

your vision of me flipping over the back of the bike or constantly loosing the front end and crashing may well be a little over exaggerated! However we will see!

That's my honest opinion, not a hyperbole.

 

[Old_Dave]

That's my honest opinion,

My first build with a big rear box stuffed with 3 sla batteries, popped wheelies with ease.

My son said I was far to old to behave like a yob and had to stop it

Lighter batteries in a different box that was moved more forwards fixed it.

 

[Quark]

I'm also far too old to be a yob but the occasional wheelie wont hurt anyone! If it does turn out to be dangerous to ride then I will have to move to a new frame sooner than expected, but I've ridden some insane bucking bronco motorcycles in my time, so I can take a fair amount of instability before panic sets in lol

 

[Deleted member 4366]

With motorbikes, if you get a bit of slippery road to negotiate, you can slow down, and the motor will then make less torque. On an electric bike, when you slow down, the torque goes up, which is what causes all the problems. The effect is just about noticeable with 15 amps, with 25 to 30 amps, you have to be careful. By the time you get to 40 amps, it gets decidedly dodgy, and 80 amps will need additional electric system to tame the throttle. Hopefully, you'll be able to tell us all about it soon.
Ebike throttles/controllers use speed control, not at all like power control that you get with a motorbike, so when you open the throttle just a little bit, you get very high torque as the controller tries to match bike speed to that set on the throttle. I shouldn't really call it a throttle because it doesn't throttle anything.