W.O.T. Addiction-Withdrawal

General Discussion about electric bicycles.
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DrkAngel   10 GW

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W.O.T. Addiction-Withdrawal

Post by DrkAngel » Apr 20 2013 10:36am

Your first eBike experience is likely to be some cheap store bought item.
In the USA this would be something in the 250-500w range with a top speed of ~15-16 mph.
Often with a limited controller, as an attempt to minimize inefficiency and maximize the severely limited range.
The limited speed and power exude anemic performance!

Not surprisingly, these limitations tend to promote an all or nothing mode of throttle usage.
No harm done? ...
The typical manufactured eBikes seem to be safety regulated to endure this ... abuse?

Yes ... my first eBike was an eZip Trailz with a 450w motor and a paltry 16mph top speed, typically used in a WOT (Wide Open Throttle) manner only.
An on-off switch from battery, direct, to the motor might have been more appropriate!

It was not till I upgraded to a 36V battery that I was forced to begin weaning myself away from my acquired WOT addiction.
With a 23-24mph top speed I was forced to reduce-regulate the throttle. (20mph legal eBike speed limit)
More importantly, with the newfound 675watt of motor output it became important to closely consider the temperature of the motor, and controller.
42v(36v battery at peak charge) x 35A(controller) = 1470 watts of power input at full throttle.
This is an initial ~1500 watts of heat production WOT from a dead stop!(0% efficiency point)
(1500w is he heat output of a fair size electric heater ... inside an electric motor the size of a soup bowl.)
Reducing to a WOT 675w heat production and 675w power output when near to 12mph, (50% efficiency region).
Near top speed, amp input decreases(~10A) and efficiency increases (~80%) for 42V x 10A = 420w input.
420w input x 80% efficiency = 336w motor output + a mere 84w heat production.

Yes ... I have a math background, physics too.
Heat is the enemy - efficiency is the friend!

The Cure

1. Reduce throttle! ... Efficiency range of the BCM (battery-controller-motor) shifts, dependent on throttle position!
1/2 throttle turns the 12mph (WOT)50% efficiency range into the 80% efficiency range.
Judicious throttle usage could produce an 80% efficiency rate at all speeds!

Of course this would produce a pitiful start from a dead stop.
So you want to get to a healthy efficiency range quickly ...

2. Pedal assist the motor getting to the efficient range of the BCM.
With lower gears, at low speed, a human can handily apply a brisk acceleration, quickly putting an eBike into a
healthy region of it's power and efficiency curves.

Reasonable throttle usage and fast feet/quick shifts allow me to jump ahead of traffic from any red light ... takes them almost half a block to catch up to me, cruising at my 20mph.
Last edited by DrkAngel on Apr 22 2013 9:18am, edited 9 times in total.
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Chalo   100 GW

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Re: W.O.T. Addiction-Withdrawal

Post by Chalo » Apr 20 2013 10:57am

You make good points about being deliberate with throttle position.

I'd like to point out that if you pedal, there is only one correct height for the saddle. If you want to sit up straighter, you have to raise the handlebars up or bring them closer to you. There are lots of options for accomplishing this. Lowering the saddle to get a more upright position impairs your pedaling (though it is a time-honored approach among DUI bike riders).

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Re: W.O.T. Addiction-Withdrawal

Post by Ykick » Apr 20 2013 11:15am

I learn from pacing roadies - will often base throttle control on that performance spectrum. Doing so returns incredible range from a smallish battery. The ideal eBike IMO is one that an average fat guy like me can ride at mild competitive levels.

I've learned Thumb throttle allows me to wedge a bit of flesh from Thumb inbetween the rotating ring and housing. Doing so provides better overall control when demanding small increments. 'guess this is what CA can help with too and all the wonderful work Justin is putting into PAS, current based throttle, etc?
Talent must not be wasted.... Those who have talent must hug it, embrace it, nurture it and share it lest it be taken away from you as fast as it was loaned to you.

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DrkAngel   10 GW

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Re: W.O.T. Addiction-Withdrawal

Post by DrkAngel » Apr 20 2013 5:14pm

Mindless Meandering
I didn't seem to truly appreciate the joys of partial throttle till I began taking meandering journeys along the Allegheny River Valley Trail.
On hot days I take gentle cruises through the cool deeper forest.
I have a dedicated Comfort Cruiser, 20mph capable but typically cruise at 10-15mph.
Big comfy seat-suspension post lowered to the frame for a full upright seating position, comfy grips and big comfy tires ... a true pleasure ...
No pedaling, gentle starts ... elegant cruising ...
And at the lower speeds, I can cruise for hours on a charge! Image

Image

Sorry to confuse ... separated differing subject.
Last edited by DrkAngel on Apr 26 2013 11:23am, edited 2 times in total.
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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liveforphysics   100 GW

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Re: W.O.T. Addiction-Withdrawal

Post by liveforphysics » Apr 20 2013 5:44pm

Ride deathbike. :-)

You will either instantly embrace the concept of only riding partial throttle or enjoy being hoisted and thrown in the air by your groin. :-)
Each carcinogen vapor exposure includes a dice roll for cancer.

Each mutagen vapor exposure includes a dice roll for reproductive genetic defects in your children.

Each engine start sprays them into a shared atmosphere which includes beings not offered an opportunity to consent accepting these cancer experiences and defective genetics life experiences.

Every post is a free gift to the collective of minds composing the living bleeding edge of LEV development on our spaceship.

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DrkAngel   10 GW

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Re: W.O.T. Addiction-Withdrawal

Post by DrkAngel » Sep 11 2013 8:32am

DrkAngel wrote:Mindless Meandering
I didn't seem to truly appreciate the joys of partial throttle till I began taking meandering journeys along the Allegheny River Valley Trail.
On hot days I take gentle cruises through the cool deeper forest.
I have a dedicated Comfort Cruiser, 20mph capable but typically cruise at 10-15mph.
Big comfy seat-suspension post lowered to the frame for a full upright seating position, comfy grips and big comfy tires ... a true pleasure ...
No pedaling, gentle starts ... elegant cruising ...
And at the lower speeds, I can cruise for hours on a charge! Image

Image

Sorry to confuse ... separated differing subject.
2009 eZip LS keeps getting better! (20mph capable w/ 7s 25.9V Li-ion battery pack & 16T mod.)
I built a 29.6V 31.2Ah recycled Li-ion battery for my 2008 eZip Mountain Trailz, early 2008 was the last production of a multi voltage capable controller, 24V rated but runs at 37V nicely ... or so I thought ...
Turns out my $258 2009 Trailz LS (Low Step sounds better than "Ladies"), runs at higher voltages also!
8s12p 29.6V 31.2Ah, stuffed into oem pack pushes me along at 22mph.
Original purpose was to allow a 20mph capability on an oem eZip.
Rather than regearing for higher speed, with the resultant lack of torque, upping the battery voltage increases torque and ups the speed capability towards the "legal" 20 mph.
Sadly, I have been too lazy to "un-mod" the bike back to oem gearing, so I have to constantly monitor my throttle to "keep it legal".
20mph w\9-16T mod / 25.9V x 29.6V = 22.86mph
16mph w\9-20T oem / 25.9V x 29.6V = 18.29mph

OEM Trailz w/road tires should cruise at 20mph.
Last edited by DrkAngel on Sep 11 2013 10:27am, edited 1 time in total.
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 - November 2018

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

etriker   100 kW

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Re: W.O.T. Addiction-Withdrawal

Post by etriker » Sep 11 2013 9:50am

2 ways.

1. ride out way out in the woods.

2. ride with my wife Nancy. :)

( riding is kinda boring without her )

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DrkAngel   10 GW

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Re: W.O.T. Addiction-Withdrawal

Post by DrkAngel » Sep 11 2013 10:28am

DrkAngel wrote: 2009 eZip LS keeps getting better! (20mph capable w/ 7s 25.9V Li-ion battery pack & 16T mod.)
I built a 29.6V 31.2Ah recycled Li-ion battery for my 2008 eZip Mountain Trailz, early 2008 was the last production of a multi voltage capable controller, 24V rated but runs at 37V nicely ... or so I thought ...
Turns out my $258 2009 Trailz LS (Low Step sounds better than "Ladies"), runs at higher voltages also!
8s12p 29.6V 31.2Ah, stuffed into oem pack pushes me along at 22mph.
Original purpose was to allow a 20mph capability on an oem eZip.
Rather than regearing for higher speed, with the resultant lack of torque, upping the battery voltage increases torque and ups the speed capability towards the "legal" 20 mph.
Sadly, I have been too lazy to "un-mod" the bike back to oem gearing, so I have to constantly monitor my throttle to "keep it legal".
20mph w\9-16T mod / 25.9V x 29.6V = 22.86mph
16mph w\9-20T oem / 25.9V x 29.6V = 18.29mph

OEM Trailz w/road tires should cruise at 20mph.
Worse! I found that by removing the center screw and staggering the cells, I can shoehorn 9s12p 33.3V 31.2Ah into the oem pack!
20mph w\9-16T mod / 25.9V x 33.3V = 25.71mph
16mph w\9-20T oem / 25.9V x 33.3V = 20.57mph

So, until I drop my bike back to oem gearing I must apply constant throttle restraint ...
To maintain legal speed and ...
To limit heat production!
I have run an alternate eZip, unmodded, with 9-20Tgearing, at 37V for 4000+ miles with no overheat problems.

Fortunately! It looks like 33.3V will keep the oem eZips near the "legal" 20 mph limit!
Rather than the 20% torque loss associated with the 16T mod, going from 24V to 33.3V (100% /24 x 33.3 = 138.75% torque)
So a 25% speed and ~40% increase in, acceleration-hill climbing torque, turning the lackluster eZip into a reasonably respectable machine.
Upgrading to 36V controller will allow 33.3V and 37V Li-ion use, 30-31V low voltage cut off works nicely with 33.3V Li-ion, 37V DOD will have to be monitored more closely.
PAS function is sacrificed with most aftermarket controllers.

OEM 24V 10Ah SLA pack = .240kWh @ 10A discharge = .120kWh usable capacity (1C discharge rate).
Upgrade 33.3V 31.2Ah Li-ion pack = 1.039kWh @ 10A discharge = 1.000kWh+ usable capacity (<.3C discharge rate).

Oh! and the 1.000kWh usable Li-ion pack still weighs noticeably less than the .120kWh usable SLA battery!
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 - November 2018

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

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DrkAngel   10 GW

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Re: W.O.T. Addiction-Withdrawal

Post by DrkAngel » Sep 13 2013 8:29am

I just created a voltage performance graph for the venerable Unite My1018z 450w permanent magnet gear reduction motor.
This is a comparison of reasonably expected torque and speed profiles from various voltages.
MY1018zs.JPG
MY1018zs.JPG (47.12 KiB) Viewed 1081 times
Points
Resistance line is a reasonably accurate representation of a combined road and wind resistance, based on a mountain style bike with rider in a "normal" position.

Torque line is based on an unlimited controller, typically controllers provide less torque at low rpms and would represent as fairly horizontal deviation at lowest rpms. While cheaper to manufacture, this also helps diminish damaging heat.

Higher voltages, especially at lower rpms can produce damaging heat!
Limiting throttle at inefficient lower speeds or using a lower amperage controller helps keep the motor from "burning up".

Efficiency with full throttle from:
a dead stop is nearly 0% = ~100% (1000w) wasted heat!;
mid speed is nearly 50% efficient, 500w heat and 500w power;
near top speed efficiency increases to near 80% for 200w heat and 800w power.

With throttle restraint at lower speeds, (or a limited amp controller), a motor run at 48V might suffer less damaging heat at full speed than at 24V "dogging it" up hills etc.
Oh! And reducing a controllers amps by half ... only affects-diminishes performance in the lower speed-efficiency region!
Full throttle - controller+motor drains full amps at 0 rpm, this amp drain diminishes as speed and efficiency increase till amp drain is minimal at top speed - nearly 0 amps at maximum no-load speed.
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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 - November 2018

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

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docnjoj   100 GW

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Re: W.O.T. Addiction-Withdrawal

Post by docnjoj » Sep 13 2013 9:12am

Hi DKAng
Are you using N/m or ft/lbs for torque values?
otherDoc
E-bike stable at our house

Steintrike Mad Max full suspension trike rear Cute 100H going on: Whoops, Cute wheel broke but I fixed it.
Sun USX delta trike EbikeKit small geared front wheel sort of front suspension for wife

Agniusm/A123 AMP 20 36 volts on the Steini has been taken off.
2x16000 Multisport from HK now gone as they died after 2 years
New Luna 10S bottle battery 13.6AH now on mine
Relatively New 10S4Px2 for wife's bike giving 20ah @ 40 volts home made Panasonic from Tumich. BMS's rule.

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DrkAngel   10 GW

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Re: W.O.T. Addiction-Withdrawal

Post by DrkAngel » Sep 13 2013 10:23am

docnjoj wrote:Hi DKAng
Are you using N/m or ft/lbs for torque values?
otherDoc
Neither ... sorry ... torque values are based on 100% of oem - 24V. (100)
48V = 200%, (200), etc.
Comparative values, for this motor only.
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 - November 2018

EBike Toolbox - Bargains! $

Endless Sphere Wiki - Lost?

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