Rebuild BM2 green...

[Burgerman]

:mrgreen: Wish I could use my hands to build stuff.

You can use others hands as I mostly have to do. You learn to instruct!

[Burgerman]

Lights. Very hard to photograph. The yellow ones will be red LED when they arrive. So all will be red.

They are lots brighter than this seems to show. Sunglasses required!

Evening, room lights...

Daylight...

[expresso]

Love it- very nice -

[hank]

Has Santa been with your new Cobra Seat.

[Burgerman]

Not yet... Waiting. But THEY get it on the26th, so I get it 2days later...

[SteveO]

Lights. Very hard to photograph. The yellow ones will be red LED when they arrive. So all will be red.

They are lots brighter than this seems to show. Sunglasses required!

Evening, room lights...

810_1344.JPG

Daylight...

810_1342.JPG

[quote="Burgerman"]Lights. Very hard to photograph. The yellow ones will be red LED when they arrive. So all will be red.

It's looking great, can you post a link to where you got the led bulbs from or did you have to replace the whole fitting? Either way can you do a link please? Also you added a 45 degree thermal switch for the fan, could you show us exactly where and how you fitted the switch and which fan you used as I'd like to do the same to mine
Thanks John

[Burgerman]

http://www.ebay.co.uk/itm/361442455527? ... EBIDX%3AIT

http://www.ebay.co.uk/itm/380891608375? ... EBIDX%3AIT

http://www.ebay.co.uk/itm/121215117549? ... EBIDX%3AIT

some use different! Take a look first.

Thermal switch was out of my pile of bits. Came from an old power supply. http://www.renge-components.com/photo/p ... mostat.jpg Like this. 40C woulds be better.

[SteveO]

http://www.ebay.co.uk/itm/361442455527?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

http://www.ebay.co.uk/itm/380891608375? ... EBIDX%3AIT

http://www.ebay.co.uk/itm/121215117549? ... EBIDX%3AIT

some use different! Take a look first.

Thermal switch was out of my pile of bits. Came from an old power supply. http://www.renge-components.com/photo/p ... mostat.jpg Like this. 40C woulds be better.

That's great, thanks and those bulbs just go in as a direct replacement? And how do you attach the thermal switch to the PM and then to the fan?

Cheers John

[Burgerman]

The chip is fixed with epoxy inside the case, the wires go in series with the computer fan. And a resistor to give approx 12V and connected permanantly to the 24V supply.

[jim4472]

Info from my duff 80 amp controller fets

IRF100N

IR037T

2Q 8K

Data Sheet
http://www.irf.com/part/_/A~PB-IRF1010N

hopefully this will help with Irvings request.

Jim

[Burgerman]

https://www.google.co.uk/url?sa=t&rct=j ... RQ&cad=rja

Barely 80A capable, and theres no heatsink as such in the pilot plus, and they are 11mOhm...

[SteveO]

The chip is fixed with epoxy inside the case, the wires go in series with the computer fan. And a resistor to give approx 12V and connected permanantly to the 24V supply.

So I epoxy the switch directly to the inside of the case near the mossfets and run two wires to the positive wire on the fan, obviously splicing into the pos wire. The connect the fan wire direct to the batteries via a resistor? Or even just to one of the batteries? Sorry to be a pain in the ass but I don't want to get it wrong.

Thanks John

[Burgerman]

Yes. Never connect anything to one battery...

[ex-Gooserider]

The chip is fixed with epoxy inside the case, the wires go in series with the computer fan. And a resistor to give approx 12V and connected permanantly to the 24V supply.

So I epoxy the switch directly to the inside of the case near the mossfets and run two wires to the positive wire on the fan, obviously splicing into the pos wire. The connect the fan wire direct to the batteries via a resistor? Or even just to one of the batteries? Sorry to be a pain in the ass but I don't want to get it wrong.

Thanks John

NEVER, EVER, CONNECT ANYTHING TO JUST ONE BATTERY IN A SERIES SET!!!! Always connect across the entire set and design the circuit to produce the desired voltage to the important bits if they don't run on the set voltage*.... Tapping into just one battery in the set will produce an imbalanced load and damage the batteries by causing them to charge unevenly. Search for threads on the need to 'balance' or equalize the charge in the batteries if one wants maximum life out of them. One of the minor advantages of BM's car charging setup is that it automatically balances the batteries any time he hooks up to it.

In theory if one only charged in parallel, the imbalance caused by connecting to just one battery would be corrected each time you charged, but it still isn't a good idea, as you'd be discharging to unequal depths of discharge.

* Getting the desired voltage is an electronics 101 thing, as it is pretty simple, and it is best if you understand the theory, but for chair stuff, the three basic approaches are to:
1. Use two identical 12V devices in series, so they split the 24V from the pack;
2. Use an equivalent value resistor to drop the undesired voltage and dissipate it as heat - make sure the resistor has the wattage rating and be careful where you put it!
3. Use a DC-DC converter.

I will leave it as 'an exercise for the student' to explain how / why each approach works, and the costs / benefits of each....
(doing this will help your understanding, so it's worth the effort....)

ex-Gooserider

[SteveO]

This is reason I ask my questions before doing anything first. Thanks John and exGooserider for your valuable advice which is priceless to me. Now, before I do anything I will accept your "student' to explain how / why each approach works, and the costs / benefit" exercise and post my findings here afterwards. Just coming on here everyday stops my brain turning to mush but it pleases me no end that you are all here to freely offer your fantastic advice making it possible for us to take control of our lives.
Tank you

[hank]

Any luck with your new Seat John.

[Burgerman]

Email this morning, 16th to 18th.

But stuck on bed with a sore so might not be an issue...

[hank]

Sorry to hear that. get well soon.
No rush for new seat yet then.

[nandol]

Next job. Making the powerchair RELIABLE!

Stock powerchair motor couplings, on most powerchair motors, or rubber cush drives if you prefer, fail with monotonous regularity. As soon as you fit decent low resistance batteries (throw away those gels), fit decent wiring, and program the chair to turn, stop, and go.

I have a draw full of these failed ones. From 3 different motor manufacturers. It feels like a gearbox failure, but in reality its a £2 part... Most are similar. What happens is that suddenly you put some real torque through them. And the outside case splits, jams under load as it expands.

I fix these now BEFORE they can fail.

The problem: (Good one on the right...)

olá Fellas,that part also fail in my motor two or three weeks after the old lady crash my chair with her vehicle
I already send this link to ivanov so he can from now on fix this problem, he also says the right motor is kaput,and i have to buy a pair of new ones

In Brazil you can drive a car with or without insurance...and its legal !!

[Burgerman]

I have to do the same to fix my BM3 too.

No insurance... Its the wild west over there still.

[shirley_hkg]

Can't resists the temptation of tubeless . Shirley_hkg goes tubeless too .

[expresso]

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

its larger also - so you gain speed ?

[Burgerman]

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

[shirley_hkg]

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.


ON A BURNING AFTERNOON LAST YEAR :




I may hit 20 kph down hill this summer.

[Burgerman]

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.

[shirley_hkg]

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 .

[Burgerman]

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

[expresso]

nice long ride - love the speed - shirley -

[ex-Gooserider]

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.

ex-Gooserider

[Burgerman]

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.