Motors - what's the story?

[RedAlH]

I'm looking for my next powerchair.

I have been using an Invacare storm 3 TT for the past 12 years and it's been excellent. I was anticipating that the quiet, smooth, brushless motors that i've been using would by now have been widely adopted.
I'm surprised to discover that this doesn't seem to even be an option.

I tried a Q500R yesterday and it was horrible! My storm did have the controls remapped slightly (can't remember exactly as it's so long ago), and it's a 13kph chair compared to the sluggish thing I tried yesterday, but the Q500 was noisy, notchy and barely controllable.

Is this really what everyone else is using?

[martin007]

I'm looking for my next powerchair.

I have been using an Invacare storm 3 TT for the past 12 years and it's been excellent. I was anticipating that the quiet, smooth, brushless motors that i've been using would by now have been widely adopted.
I'm surprised to discover that this doesn't seem to even be an option.

I tried a Q500R yesterday and it was horrible! My storm did have the controls remapped slightly (can't remember exactly as it's so long ago), and it's a 13kph chair compared to the sluggish thing I tried yesterday, but the Q500 was noisy, notchy and barely controllable.

Is this really what everyone else is using?

And worse things...

[steves1977uk]

Brushless motors are for light Chineseium chairs with lightweight persons, otherwise they draw too many Amps which overheats the Power module and then you have to wait for it too cool before the chair works again. This is common on heavy rehab chairs. Invacare went back to brushed motors with gearbox because they weren't suitable for some users.

Steve

[Burgerman]

I ordered a brand new one. And bought a cheap 2nd hand one to experiment with. And discovered HUGE problems with brushless generally.

Both the brushless chairs, I reprogrammed so that they steered and were properly controllable. You have to do that with EVERY chair.

But the problem was this. I am a heavy person. And the brushless motors simply do not have adequate torque. They pull a rediculous 191 Amps from the battery when turned in place (measured on the rear drive storm xplore chair) without a user sat in the chair! So after two to three turns in place the power module cries enough. And rolls back power to save itself and the batteries/cables from damage. And it was so bad that I literally struggled to get it to leave the house. I contacted the designer at invacare who after hearing what my issues were and what I measured admitted that there was a massive design issue and collected my chair. Refunded me in full. Then they stopped supplying them completely.

How exactly anyone gets them to move around in any sort of proper control absolutely baffles me. Thats only posible with an empty chair or a super light user provided its programmed in such a way that it would suit my grandma. So thats the story and the problem with them. There is no solution.

When rolling and not trying to turn in place they are quiet, and great for range and the suspension on the explore chair was the best of any chair I ever had. And I had a few!

The Q500 rear drive is also problematic. It CAN be made to steer properly and there are 8mph motors possible. But if you tested a typical 2 pole 6mph or 4mph one then they also dont have adequate torque. You need the thing PROPERLY programmed, and you need the R-Net controls, (not VR2) and you need the 120A power module (not the 90A one) and you need the seat moving back!!! Thats very hard to do on that chair. As the casters are too close together. And you MUST get the 4 pole high torque motors...

I moved the seat back, by ordering a centre footplate, and fitting smaller diameter front tyres on the very similar Q700R chair. It allows the heels to sit slightly between the casters, and so allows the seat to be moved rearwards. Turning an oil tanker indo a usable chair.

See: https://www.wheelchairdriver.com/board/ ... 33#p171026
Please read the whole page! Details make a huge difference.

[martin007]

How much do you weigh?

[Burgerman]

Was 20stone. Now about 16... Dieting. Well within the chairs specs regardless.

[martin007]

In Spain we use kg.
I calculate that I weigh between 60 and 70 kg.

[Burgerman]

20 stone 127kg
16 stone 102kg

Chair is for up to 150KG

https://www.invacare.co.uk/power-wheelc ... wheelchair
They junked the brushless. And now it uses 4 pole motors. But also that godawful linx control system so you cannot program it to steer properly. Or I would get another! 4 pole motors are much much better than the brushless junk.

[martin007]

I'm about 180 cm tall, but I'm a pencil.

[Burgerman]

In your case I would buy a suitable chair new. Run over the old one with a tractor. Then send the bill to the doctor with a solicitors letter saying you had no choice.

[RedAlH]

Hmm. I don’t understand how your results correlate with my real world experience of the last 12 years. I don’t doubt what you are telling me, I’m just surprised.

I’m probably 14 stone, haven’t been weighed in years. I’ve used my chair all day, every day for all manner of things. Climbing kerbs, walking the dog on rough terrain, giving my mrs a lift home from the pub when she’s drunk too much etc.

In that time I’ve replaced 1 motor, a couple of power modules and one joystick. It’s been a great chair which is why I’ve held onto it for so long.

I’m at a loss what to look at for a decent replacement.

[Burgerman]

Delayed action and slow steering which they programmed in especially badly on that chair was done partly to disguise the issues. But I cannot drive a chair programmed that way. So I programmed it to respond properly. And then it tries to take even more current in order to do as its told. Thats when it starts actually cutting out. Or run it up against a curb and stop. Then try to climb it a couple of times with no run up. 1st you notice it cant... (not enough torque) And then it cuts out and you are screwed till it cools.

I know you had someone program it but it had walls set up by he factory that wouldnt actually allow you to do this properly even if you wanted to. So unlesss you had access to a real OEM or in fact engineering level programmer you woudnt be able to adjust the turn acceleration scaler in order to actually program the chair to steer properly anyway. That and the fact that you are around 4 stone lighter probably combined to desguise the issues. But they tried (from invacere) to make it work for 2 months and it just couldnt be done. And I wasnt the first. The guy that designed these motors at invacare/PG already understood the problems and why it was happening when I spoke on the phone. He was surprised that I did too. He realised that in order to get adequate torque at a sensible current level you must have gearing. Making the direct drive motor diameter bigger would do the same thing. But you cant really have it any bigger than it is, as its already the same diameter as the tyre internal. Hence the problems.

What you are looking for in your next rear drive chair is:

a) centre mount footrest.
b) so that it allows you to move the seat back and take all that weight off the front casters, and put it over the drive wheels As that makes the whole chair easy to turn, shorter, and keeps the drive wheels from slipping on loose ground or wet leaves etc. Make the whole chair way way better.
c) 120A Rnet control syste,
d) 4 pole motors.
e) access to a programmer. You dont need OEM because there are ways to do the things you need to do without this.

Everything else like seating, etc is an afterthought. Get a to e above right first!

[RedAlH]

Thank you, I appreciate the advice.

I have remembered that the seat was moved back on my storm to improve the manoeuvrability and balance.

Unfortunately, I can’t use a central footplate with the way my legs behave, but I’ll take the rest onboard.

[Burgerman]

Then the problem you have is that every rear drive chair will drive like an oil tanker because your feet must sit ahead of the rearward facing caster wheel when you reverse. So that means way too much weight over the caster tyres, and evil heavy feeling steering. And rear wheel traction reduced so that the tyres slip in many situations. It makes the chair very unweildy indoors hard to turn into and out of rooms or turning in tight spaces. And it eats more battery. This sadly is how most rear drive chairs are sold. That combined with the weedy motors (2 pole) and stupid programming, and swing away foot riggings and you can see how rear drives get such a bad reputation indoors. They CAN be as good as mid drive in tight places. With your backside sat mostly over the drive wheels. And a short narrow centre footrest.

It might pay you to look at a few centre drive chairs or the sunrise Q chair that is called the 500H (hybrid). Or similar chairs such as the rear drive Dietz ones.

[martin007]

Hmm. I don’t understand how your results correlate with my real world experience of the last 12 years. I don’t doubt what you are telling me, I’m just surprised.

I’m probably 14 stone, haven’t been weighed in years. I’ve used my chair all day, every day for all manner of things. Climbing kerbs, walking the dog on rough terrain, giving my mrs a lift home from the pub when she’s drunk too much etc.

In that time I’ve replaced 1 motor, a couple of power modules and one joystick. It’s been a great chair which is why I’ve held onto it for so long.

I’m at a loss what to look at for a decent replacement.

Burgerman has given you some ideas.

I recommend you to look at the Sunrise powerchair catalog.
It's advisable to check the weight and dimensions of the powerchair.
A lighter powerchair consumes less energy.
One more centimeter of width is the difference between accessing (or not) a place.
A powerchair with a high center of gravity is unstable and unsafe.
The capacitance of the batteries is crucial.
I would stay away from 6 wheels powerchairs.

[Burgerman]

Get a 4 pole motor, 120A R-net one of these. https://dietz-power.com/advanced/

Has all seating options avaialable, better buid quality than sunrise according to a rover a chair tech on here, and has GRP24 battery, etc. Every box ticked.

[RedAlH]

Thank you all for the advice. It’s very much appreciated