EZip 450w - Re-Gearing for 30mph w/Pedal Assist

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DrkAngel   100 GW

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EZip 450w - Re-Gearing for 30mph w/Pedal Assist

Post by DrkAngel » Sep 05 2012 1:22pm

I started with a 2008 EZip Trailz ... several years ago ...
I keep coming to the point of outgrowing it!
But ... I keep coming up with "improvements" that prolong it's usefulness.

1st I found a 16T compatible freewheel, this allowed a 20mph cruising speed, up 25% from oem.
20 mph Upgrade - $20

2nd I developed high capacity - long range Li-ion battery packs, recycled from laptop batteries.
Homemade Battery Packs

Now my eZip provides cruising at 22mph, with some assist till near 25mph.
Sadly, I need to jump in front of, and try to stay ahead of, 30 mph traffic!
While my eZip helps me get up past 22mph, above about 24 mph it is all me, humping along, dragging a heavy bike.
So ... I decided to re-gear for higher speed.
Motor side freewheel sprocket is at it's limit with the 16T, so increasing the motors sprocket is the other method.
(Increasing voltage would accomplish my goal ... but that is another story.)

I've never been able to find a Plug-n-play component.
Finally I came across a good candidate.
Best of all it might require only minimal modification!
"Drive Sprocket 12 teeth for #410 Chain"
Click on Picture!
Image $23.99/shipped

Multiple items cheaper from fancyscooters.com.
"Drive Sprocket 12 teeth for #410 Chain"
Most important ... the 11mm ID should fit perfectly.
"Spaces" might be easily modded to the 4mm needed, for the "key".
Small file work might suffice?
Probably easier to modify "key".

Projected "no load" speed will be 33.3mph.
Placing , my target , 30mph speed (90% of no load speed), near the end of the effective power curve.
______________________________________________________________________

Received my 12T upgrade candidate.
The all important 11mm ID seems usable - 11.07mm - can't get much closer to perfect.

2 factors require modification.

1. Width of the body.
OEM is 9mm, the replacement is 12mm.

Image
3mm removal with grinder seems easy enough.
Shaft is long enough to allow no mod.
But ... gauged resizing would allow precision sprocket alignment!

2. The inner shaft grooves are 3mm in width, the 4mm "key" requires a wider "keyway".

Image
Solution - rather than attempt an extremely difficult internal resizing of the sprocket, I will break out my dremel tool and grind the appropriate 1mm from one edge of the key.
Should be fairly simple to accomplish.
______________________________________________________________________

Key - modded
12T key.JPG
12T key.JPG (23.69 KiB) Viewed 1565 times
Fits nicely
Keyed.JPG
Keyed.JPG (20.31 KiB) Viewed 1612 times
9T vs 12T
9T_1.JPG
9T_1.JPG (15.69 KiB) Viewed 1612 times
12T_1.JPG
12T_1.JPG (36.63 KiB) Viewed 1612 times
Just gotta slap it on a bike and take er for a spin.
Jammed up a toe & real busy. .
Want to be in good shape for assist trials.
.. but will provide details-results soon!
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

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EvoBikeShop   100 W

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Re: EZip 450w - Re-Gearing for 30mph w/Pedal Assist

Post by EvoBikeShop » Feb 24 2013 10:13pm

Just an fyi, you can get a 13t sproket from gng. Go to thier website and go to the parts page, you can find it there. I have on installed on my currie motor.

EBS
My bike (a work in progress) 30mph club on 20's! Sold and missed.........
http://endless-sphere.com/forums/viewto ... 28&t=46977
EvoBikeShop wrote:This ebike thing is an addiction.

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DrkAngel   100 GW

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Re: EZip 450w - Re-Gearing for 30mph w/Pedal Assist

Post by DrkAngel » Feb 24 2013 11:01pm

http://www.gngebike.com/parts

Image

Got 1, proper fit, just needs longer chain.
Should push eZip with my 22.2V 41.6A Li-ion pack at 20mph!
Will post trials in its own thread ... after Spring gets Sprung.

15T also available.
See - Re-gearing the eZips Simple Mods
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - February 2019

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

User avatar
DrkAngel   100 GW

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Posts: 5157
Joined: Dec 15 2010 11:14am
Location: Upstate-Western-Southern Tier NY. USA

Re: EZip 450w - Re-Gearing for 30mph w/Pedal Assist

Post by DrkAngel » Mar 09 2014 12:09pm

Of course 30mph with a 450w output motor is pretty darn tough to maintain.
30mph with a mountain bike requires ~1000w output.
Even a race bike requires >700w.
Leaving a required 250-550w pedal contribution!

Image

So ... gotta pump up the motor output ...

Upping the motor voltage pushes the wattage output up!
24V = 450w
25.9V = 485w
33.3V = 625w
36V = 675w
44.4V = 832.5
48V = 900w

I graphed the drive train outputs for a multi-speed crankdrive and was able to determine 44.4V as optimal, (with proper gearing), for a 30mph capable eBike.
Crank Drive 44.4V2.jpg
Crank Drive 44.4V2.jpg (104.92 KiB) Viewed 1085 times
Now 44.4V can be damaging to a 24V motor.
Solution! Well ... patch or fix, is to limit amps.
Typical 48V controller might be 40-50A, limiting controller to 25-30A? will limit low speed acceleration but should allow full motor output at 30mph optimal point.
At low speed, a high percentage of amps are wasted as damaging heat.
Efficiency reaches more acceptable when motor attains >40% of no load speed.

Image
Cutting input amps almost in half will have no effect on peak motor output!
But it will reduce low speed full throttle energy waste - damaging heat production.
Yes ... it will also reduce "off the line" acceleration, but not that much of a priority ... to me.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There, shallow draughts intoxicate the brain,
And drinking largely, sobers us again.

I enjoy enlightening ... and enlivening the spirit of the innovators.

New & Improved - Acronym Definitions

Index - Homemade Battery Packs - Updated - February 2019

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

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