22.2V - Battery Woes!

Batteries, Chargers, and Battery Management Systems.
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DrkAngel
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22.2V - Battery Woes!

Post by DrkAngel » Mar 18, 2013 10:44 am

I have been testing a prototype 22.2v 41.6Ah pack, on 24V ezip eBikes.
Range is very impressive, weather turned lousy so full results delayed, but performance seems anemic ... at best.

Of course, it is possible that I have just become spoiled.
My typical battery builds run at 25.9V.

After deducting road load and wind resistance, there is a certain amount of available torque for acceleration.

Hmmm ... As shown in the following graph, at 16 mph, after you deduct road and wind resistance, my 25.9V pack supplies more than 2x the available torque compared to my 22.2V pack.

Image
No wonder the 22.2V pack seemed anemic!
Of course, at lower speeds, this difference diminishes, but it is extremely important to consider torque differences at your project speed goals!
Who would have thought that a 12% decrease in voltage would make such a drastic difference at performance.
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Re: 22.2V - Battery Woes!

Post by wesnewell » Mar 18, 2013 11:09 am

ROFLMAO. If you want to twist the facts, why not just base it on 18mph where the difference figured your way puts it at a lot more than 2x. In reality the difference is constant at all speeds.
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etriker
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Re: 22.2V - Battery Woes!

Post by etriker » Mar 18, 2013 11:27 am

Some women weigh close to about 110lbs and don't need or like a lot of power on an ebike.

22.2v pack could be just fine ?

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Re: 22.2V - Battery Woes!

Post by liveforphysics » Mar 18, 2013 5:41 pm

etriker wrote:Some women weigh close to about 110lbs and don't need or like a lot of power on an ebike.

22.2v pack could be just fine ?

22v is plenty to make at least 50 times the 750w ebike guideline.

Just requires larger cables and a motor wound to be optimized for 22v. His specific example is tied to a BEMF related artifact of inability to draw more power at speed with one than the other over one having the couple extra volts it needed to exceed the BEMF voltage to allow one to draw full current and one can't.
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Re: 22.2V - Battery Woes!

Post by DrkAngel » Mar 18, 2013 6:01 pm

22.2V packs hold a couple nice perks:
1. The majority of recyclable laptop packs are in a 3-cell 11.1V configuration.
2. With a fair sized pack the LVC on a 24V controller cuts off at a safe-reasonable 20-21V.
(similar for 33.3V with 36V controllers, 44.4V with 48V controllers etc.)

Regearing, as with eZips-iZps etc., can shift the degree of torque and assisted top speed. See - Re-gearing the eZips-iZips
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Re: 22.2V - Battery Woes!

Post by DrkAngel » Apr 08, 2013 12:59 pm

22.2V - 41.6Ah eZip pack.

Still segregated into 2 - 22.2V 20.8Ah banks ... not done testing yet.

Image

I think that I must apologize for the badmouthing I have been laying onto this pack.
With the warmer weather and most especially the 13T modded 2013 eZip, performance is delightedly ... acceptable.

13T Mod
2013 eZip Trailz LS
Attachments
22.2v 41.6Ah.JPG
22.2v 41.6Ah.JPG (72.62 KiB) Viewed 1393 times
A little learning is a dangerous thing;
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There, shallow draughts intoxicate the brain,
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I enjoy enlightening ... and enlivening the spirit of the innovators.

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Re: 22.2V - Battery Woes!

Post by DrkAngel » Apr 14, 2013 11:58 pm

A fairly accurate comparison of my 22.2V pack vs my 25.9V pack.
22.2V vs 25.9Vs.JPG
22.2V vs 25.9Vs.JPG (72.12 KiB) Viewed 1257 times
Available torque, above the road load - wind resistance curve, is the most noticeable difference.

A lightweight with aerodynamic curves would likely be happy with the 22.2V 40Ah+ pack, but at 200lb and having tasted 25.9V, I don't believe I could be.
Might be perfect for the cyclist looking for prolonged assist?
A little learning is a dangerous thing;
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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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Re: 22.2V - Battery Woes!

Post by emiyata » Apr 15, 2013 2:22 am

DrkAngel wrote:A fairly accurate comparison of my 22.2V pack vs my 25.9V pack.
Converting from a 24v brushed motor to a 48v brushed motor at the same wattage would help reduce losses,if that is your goal. It would be a major change but going to a brushless would really help get better efficiency.
Having the battery voltage below the 24v point really cuts the power down.
You would have been better off using the same amount of cells but wire them for 1S more than 25.9 at the cost of 1p. Voltage sag would be more but the way you ride the bike I don't think you would notice it. Less current means less losses.

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Re: 22.2V - Battery Woes!

Post by DrkAngel » Apr 15, 2013 11:47 pm

22.2V 41.6Ah pack getting rewired as 44.4V 20.8Ah.
Partly to protect cells and motor I will use a 20V - 72V, lowly 25A controller.
This will also allow me to try a 29.6V 31.2Ah pack. This will allow full use of an iMax B8, as charger balancer..
Lowering amps will limit damaging waste-heat at lower speeds while allowing zippy higher speeds!
Both use the maximum 18650 cells that can be squeezed into an eZip pack.

2008 eZip Trailz will become my testbed for overvolting, will be 22.2V to 72V capable, eZip pack or bulk pack.
I don't plan on producing anything with an excess of 30mph capability, I personally don't have a purpose for it ... as an eBike.
That is eMotorcycle territory ... as far as I'm concerned.
I plan on re-building one, gas bike stripped and rebuilt, legally registered, licensed, and insured, as my logical next stage of eDevelopment.
eCar as an eventual goal, first prototype for local city traffic, adding a generator for longer range, trips etc.
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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Re: 22.2V - Battery Woes!

Post by emiyata » Apr 16, 2013 1:24 am

DrkAngel wrote:22.2V 41.6Ah pack getting rewired as 44.4V 20.8Ah.
Partly to protect cells and motor I will use a 20V - 72V, lowly 25A controller.
This will also allow me to try a 29.6V 31.2Ah pack. This will allow full use of an iMax B8, as charger balancer..
Lowering amps will limit damaging waste-heat at lower speeds while allowing zippy higher speeds!
Both use the maximum 18650 cells that can be squeezed into an eZip pack.

2008 eZip Trailz will become my testbed for overvolting, will be 22.2V to 72V capable, eZip pack or bulk pack.
I don't plan on producing anything with an excess of 30mph capability, I personally don't have a purpose for it ... as an eBike.
That is eMotorcycle territory ... as far as I'm concerned.
I plan on re-building one, gas bike stripped and rebuilt, legally registered, licensed, and insured, as my logical next stage of eDevelopment.
eCar as an eventual goal, first prototype for local city traffic, adding a generator for longer range, trips etc.
sounds like you have your share of projects. Have fun.

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Re: 22.2V - Battery Woes!

Post by DrkAngel » Apr 16, 2013 2:09 am

DrkAngel wrote: Partly to protect cells and motor I will use a 20V - 72V, lowly 25A controller.
This will also allow me to try a 29.6V 31.2Ah pack. This will allow full use of an iMax B8, as charger balancer..
Lowering amps will limit damaging waste-heat at lower speeds while allowing zippy higher speeds!
Both use the maximum 18650 cells that can be squeezed into an eZip pack.
More perks!
An eZip with 29.6V 31.2Ah pack, without any regearing, will push to 20mph capability!
With a substantial torque increase ...
A 24% torque increase, as opposed to the 20% torque decrease associated with 16T or similar with the 13T mod.
Problem is, finding a controller that is 29.6V capable.
Except for the pre-mid 2008 eZips, universal voltage controllers seem to be the only available.
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 2015

EBike Toolbox - Bargains! $

Endless Sphere Wiki

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