Rebuild BM2 green...

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Re: Rebuild BM2 green...

Postby shirley_hkg » 22 Apr 2016, 15:01

:P Can't resists the temptation of tubeless . Shirley_hkg goes tubeless too . :lol:
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Re: Rebuild BM2 green...

Postby expresso » 22 Apr 2016, 15:22

Nice -- is that tire a direct fit - bolt in ?

its larger also - so you gain speed ?
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Re: Rebuild BM2 green...

Postby Burgerman » 22 Apr 2016, 18:40

Its a 10 inch aftermarket monkeybike wheel, not sure what tyre size probably 300 x 10. But its added some speed, but also lots of height as its 16 inches diameter. And maybe caster barrel no longer vertical?

Maybe an 8 inch tubeless rim would be better? But cant be done because of motor type.

Will increase speed by 14.9% and decrease torque by the same amount. So a 7.0 mph chair now goes 8.04mph
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Re: Rebuild BM2 green...

Postby shirley_hkg » 24 Apr 2016, 07:09

Burgerman wrote: So a 7.0 mph chair now goes 8.04mph


It's a 8.5 chair that I exceeded 8.04mph long ago , with full lithium on Bridgestone 3.50-8 tyres. :lol:


ON A BURNING AFTERNOON LAST YEAR :

Image


I may hit 20 kph down hill this summer. :P
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Re: Rebuild BM2 green...

Postby Burgerman » 24 Apr 2016, 08:08

Thats 12.4mph.

Are the casters not a problem if you lift up the rear? I have the rear of the chair adjustable for height, so have the ability to lower it to keep caster barrel at 90 degrees to the road. Or very close to it limited by frame/tyre gap.
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Re: Rebuild BM2 green...

Postby shirley_hkg » 24 Apr 2016, 11:02

NO. They didn't shake even at 15 / 85 weight distribution.

Unlike snaker's case, my chair's caster stems may be not vertical but lean forward slightly . That will only extends the ground contact point from stem, not shorten it .
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Re: Rebuild BM2 green...

Postby Burgerman » 24 Apr 2016, 15:33

Actually it doesent. It reduces it slightly. You draw a line through the hinge point to the ground, and the trail is the difference between contact patch and the hinge point (projected to the ground).

But if no shake then still not a problem!

http://www.rodbikes.com/articles/graphi ... k-rake.jpg
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Re: Rebuild BM2 green...

Postby expresso » 07 Jun 2016, 09:14

nice long ride - love the speed - shirley -
Last edited by Burgerman on 07 Jun 2016, 09:15, edited 1 time in total.
Reason: So I dont lose it!
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Re: Rebuild BM2 green...

Postby ex-Gooserider » 14 Jun 2016, 05:57

Just out of curiosity, I have an OLD Storm Arrow with GB motors, I believe the first generation. (I found an invoice in the bag on the back of the chair for 'final prep' dated March 2002. The free-wheel levers are a pair of paddles at the back of the chair that twist up for free-wheel or down for drive)

Any idea what the 'official' speed rating on it should be?

I'm in the partial-rebuild process with it right now, and wondering just what I will end up with....

I'm also working on a slightly newer (2005?) Ranger-X, with gear motors, which I believe is a 6mph chair, but I'm not certain about the GB series chairs.

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Re: Rebuild BM2 green...

Postby Burgerman » 14 Jun 2016, 08:56

I think 7 or 7.5. Brushless motors dont respond the same as brushed. Max speed is usually a result of max switching frequency as programmed or hardware limited. Esp if gearless direct drive. So the same motor on a different controller such as the roboteq could be massively faster. Also depends on the "generator" voltage. Obviously once this emf volts at x rpm exceeds battery volts it wont turn faster. But that has to be thousands of RPM rather than low tens/hundreds.
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Re: Rebuild BM2 green...

Postby shirley_hkg » 14 Jun 2016, 12:32

ex-Gooserider wrote:Any idea what the 'official' speed rating on it should be?


ex-Gooserider


They are the fastest breed of the GB, rated @ 8.5 MPH, may hit 9 on pneumatic 14" tyre.. :D
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Re: Rebuild BM2 green...

Postby Burgerman » 14 Jun 2016, 14:09

That right I think from memory. They made the newer ones slower (more poles same controller frequency/speed) to improve starting torque and low speed cogging after the early ones. Theres a thread here somewhere from years ago.

I may hit 20 kph down hill this summer.
Maybe more with those wheels/tyres.
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Re: Rebuild BM2 green...

Postby Swan T.W. » 14 Jun 2016, 16:07

I have that chair. 8.5 mph is correct.
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Re: Rebuild BM2 green...

Postby funkykeyboard » 17 Jun 2016, 12:32

Burgerman wrote:Now, each individual cell is to be fully charged to 3.600V and sit at this CV voltage until its current falls to 20mA. At which point it then has 1000mA drained from it, and it goes into a pile in a box to wait for 1 month.

CHARGE 3.600V 5A
TERMINATION POINT 20mA.
REMOVE 1000mA exactly (at 5A Discharge)
STORE IN A BOX!

After 1 month, each will be fully charged once again, back to 3.600V and terminate at 20mA, and the actual mAh that was returned to each cell, (-1000) will be written on the cell in marker pen. This figure is the amount that the cell has SELF DISCHARGED (over and above the 1000mA we already removed) over the month.

This allows us to build 8 separate parallel groups, that have the same TOTAL self discharge, before assembling into the Series connected battery. It means that if we store the battery for a few months it will discharge each group at the same rate. So it will remain in balance.

2 at a time, takes FOREVER!

in layman's terms,, what is the real world consequences of not going through this laborious process? Especially on a chair that gets used virtually every day?

I think you said your builds have a 10 year life expectancy.. So would a real-world consequence be 5 years, 3 years?

aall reading it again, does it just mean it will take longer to balance?
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Re: Rebuild BM2 green...

Postby Burgerman » 17 Jun 2016, 17:38

If you randomly assemble you may get lucky or close to it anyway. The real dangers are as follows

1. Theres a rogue bad cell, and you dont catch it. Once built and discovered it is a horrible job trying to find it and unbolting the whole pack to swap it out...

2. It doesent change service life. It only means that balancing at the end of a charge will be easy. If you charge every day which you wont need too if your pack is a sensible size, or every few days in winter, it will be fine. If you have to leave it a month as I have had to, 3 months in fact, it could take several days on charge to rebalance cells worst case. Restarting the charger every 8 hours.

It was more important with the hyperion as it was 300mA balance current. The PL8 is 1000mA so 3x faster. A typical BMS is only 60 to 100 mA so that could take literally a month! So what actually happens is that they never get balanced and cells get damaged...

So you will be OK with PL8, with Hyperion too unless unlucky should still be ok, if you really do charge at least weely to be sure. After all most people never do this...

Its like balancing your cars wheels. Do you have to? No. Is it a good idea? Obviously.
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Re: Rebuild BM2 green...

Postby snaker » 18 Jun 2016, 01:51

I see BM2 has some turnbuckles at the front and the rear. Does the original F55 frame already have them? Or did you modify F55 frame to fit them?

My chair only has 2 small latches under the seat pan to change the seat angle, but the adjustable height is just 1cm. I am thinking about fitting a turnbuckle at the front like BM2. Is this job easy for a small local workshop (I mean for those who are not very skilled)? Can you give me the code name (mechanical name?) of the turnbuckles used in BM2? So I can search and buy them.

download/file.php?id=4456&mode=view
download/file.php?id=4455&mode=view
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Re: Rebuild BM2 green...

Postby Burgerman » 18 Jun 2016, 07:33

Turnbuckles? Do you mean rose joints? Self aligning rod ends? There are non on the original chair.
I use them all over the place when building cars, bikes, powerchairs because they are strong, adjustable and can be aquired quite cheaply in bulk. Almost all of the BM chairs are fabricated from fresh metals, inc footplate design, all mounting points, etc. apart from the green fat tubular frame. Including all of the seat positioning mounts, footplates, centre section, motor mountings, wheels, etc.

These are m8 Female rose joints. http://www.wheelchairdriver.com/BM3-con ... 0_0766.JPG
Mostly I use m8 Male rose joints, heres some! http://www.ebay.co.uk/sch/i.html?_odkw= ... r&_sacat=0

Take a look at a few pics of footplate, seat frame, mountings, bars etc.
There are 8 in this image:
http://www.wheelchairdriver.com/BM3-con ... hair-6.jpg

10 here:
http://www.wheelchairdriver.com/BM3-con ... hair-9.jpg
http://www.wheelchairdriver.com/BM3-con ... air-14.jpg
http://www.wheelchairdriver.com/BM3-con ... air-13.jpg
http://www.wheelchairdriver.com/BM3-con ... air-12.jpg
http://www.wheelchairdriver.com/BM3-con ... air-10.jpg
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Re: Rebuild BM2 green...

Postby snaker » 19 Jun 2016, 02:54

Yes, they are rose joints, I used wrong word "turnbuckle". I just see in a car forums site in my country, people argued about these items in 3 pages. Someone recognized "rod joint" in English but there are not equivalent words in Vietnamese. They simply called them "chicken leg" :lol:

How about the tube between 2 rod ends? Does it have a code name (e.g M8 male rose joint tube)?
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Re: Rebuild BM2 green...

Postby Burgerman » 19 Jun 2016, 08:11

No its 16mm aluminium bar. Cut, drilled, tapped to M8 as needed.
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Re: Rebuild BM2 green...

Postby Burgerman » 19 Jun 2016, 11:20

download/file.php?id=4326&mode=view

Another 8 here. And 4 alloy bars. Drilled and tapped M8 thread. And then powder coated and stainless steel washers and stainless steel locking nuts. They allow me to adjust the frame height to make sure its equal both sides, and above the bigger wheels/tyres.

In this picture only the green part is F55 and it is stock, 18 years old, powder coated green. All the rest is either modified, from different chair, hand made, or nothing to do with powerchairs...
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Re: Rebuild BM2 green...

Postby Burgerman » 22 Jul 2016, 21:13

Bump so I dont lose it...
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Re: Rebuild BM2 green...

Postby hank » 22 Jul 2016, 21:15

:lol: :lol: :lol:
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Re: Rebuild BM2 green...

Postby Burgerman » 24 Jul 2016, 09:19

You never heard that before? :)

Its quite common on forums to give the odd post a bump to get it near the top or the first page if its still relevant or waiting for a reply or something.
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Re: Rebuild BM2 green...

Postby shirley_hkg » 02 Oct 2016, 14:34

Can't you belive that ? There are really 8" tubeless . :D
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Re: Rebuild BM2 green...

Postby shirley_hkg » 02 Oct 2016, 14:36

Can't you belive that ? There are really 8" tubeless . :D
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Re: Rebuild BM2 green...

Postby Burgerman » 02 Oct 2016, 14:47

Where can I get some?
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Re: Rebuild BM2 green...

Postby LROBBINS » 02 Oct 2016, 15:40

Pity those nice looking alloy rims wouldn't work on the MicroMotor in-line motor hubs. I'd certainly rather have them than the gloss-black painted 8" trailer wheels now on Rachi's chair. BTW, those aren't the only 8" tubeless tires that can be had - Rachi has Carlisle Turf Saver 4.80 - 8 tubeless; diameter 16.5", mounted width 4.8" running at 5 psi.
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Re: Rebuild BM2 green...

Postby expresso » 02 Oct 2016, 15:47

nice tires - would love to fit those to my chair -
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Re: Rebuild BM2 green...

Postby Burgerman » 02 Oct 2016, 15:48

No they are 8 overall. Actually 9. CASTER wheels/tyres.

5 inch diameter rim, 2 inch tubeless tyre. 2+5+2=9
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Re: Rebuild BM2 green...

Postby LROBBINS » 02 Oct 2016, 17:20

Ah, that is different. What's their width?
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