Invacare

[Burgerman]

Invacere are selling powerchairs in the US again I think. So you will have a little more choice. Not sure how good they are though. The mid drives they sell here are a bit of a nothing special. And they reduced their range over the years. But it all helps competition.

[shirley_hkg]

Hope they launch Xplore there .

[Burgerman]

Remember that I am the same size as an average american. And I had issues with inadequate torque, and shutting down. So I wouldnt hold your breath.

[shirley_hkg]

We've been using the 1st generation low torque GB for the last decade . Many of us have carer onboard our piggy trolleys most of time , that added up a total load of 20 stones or more . It survives .

HD GB is more powerful .

3rd generation claims even more torque and efficiency .

Can't understand .

[Burgerman]

Chair is more nose heavy. And more heavy altogether at 190kg.

Heres what happens.
Brushless direct drive has no gearing advantage. So while its super efficient at high speed free running, in low current and straight lines its the exact opposite under stall or close to stall conditions.

8MPH 2A only at the battery. So huge range, no problem going fast in straight lines. Good range.

Turn in place is a different matter. The controller is set to boost current 125A. It needs this to turn in place. To initiate a turn, with heavy, nose heavy chair, and a heavy user takes every Amp the controller, motor, and battery can get. I measured 175A at the battery with the chair EMPTY when initial chair turn was started for around 0.5 to 1second. I then reversed thechair to a wall, still empty, and reversed it. It is programmed to give max boost of around 125A per motor, or 175A at the battery and this falls away rapidly after 1 second.After 2 or 3 seconds its 40A. And thats not enough for even moving the chair from a standstill. If you keep trying it stays rolled back and you never get any power. If you wait several minutes you can get the full 175 battery Amps back, for the same 1 second, which gets it moving again if you are lucky.

So whats the issue? The fact that it has no gearing. This means that it takes about double the number of battery Amps for any given level of torque when conpared to a geared motor like a typical powerchair motor. So if you set turn acceleration or forward acceleration to a high enough value to get proper control, the chair cannot provide adequate Amps to move you after the first second.

Why does it roll back this battery Amp figure so fast? Because one of its safety rollback features is to protect the loom, and fuse, and battery. Its called 12T COOL BATTERY and 12T MAX BATTERY. I think those are rolling back power to save the loom/battery from the enormous currents.

It also has stall rollback, temp rollback, and case temp rollback too. It may also be one of these thats doing it. But they MUST do it or the loom, module or wiring will fail. And the battery voltage drops to about 18V as you try and turn.

The reason for the massive currents is the lack of gearing and direct drive. The reason its worse on the explore instead of the mid drives, or storm 3 is that its so heavy, and also so nose heavy making it harder to turn. So its basically unworkable. They (invacare) read my diagnosis, refused to admit I was right, although couldnt offer any way to make it work, and offered a 100 percent refund. Whats more, they claim its ok for 23.6 stone users, which would be me and a small chid on my knee. Well I can assure you that will never work! So they should ammend their advertising to 10 or 12 stone max user weight.

[LROBBINS]

So if you never turn in place it would be OK? If you could get into the guts of the programming, perhaps you could set it up to turn around the CG rather than around the center of the motors. In other words, always add a little fore-aft motion whenever the stick calls for turn in place. That's something that might be worth trying with a track chair too, but in that case have it turn around the center of the inside track rather then the center between the tracks. It would widen the turning circle a lot, but cut down the power demand.

[shirley_hkg]

Chair is more nose heavy. And more heavy altogether at 190kg. .

Chair weighs that much alone ?

It certainly needs lithium @ high C rate .

A123 26650 cells are 20C .

.
. And the battery voltage drops to about 18V as you try and turn.

[Burgerman]

So if you never turn in place it would be OK? If you could get into the guts of the programming, perhaps you could set it up to turn around the CG rather than around the center of the motors. In other words, always add a little fore-aft motion whenever the stick calls for turn in place. That's something that might be worth trying with a track chair too, but in that case have it turn around the center of the inside track rather then the center between the tracks. It would widen the turning circle a lot, but cut down the power demand.

It helps, get it to turn, as I had to do that manually. But once its rlled back, after attempt one, you go nowhere.

You fix by programming wont work because if it starts to move forwards even an inch and I dont want a turn that moves backwards or forwards then I will automatically correct that with my thumb! Negating the distortion you added in programming on the fly. The problem isnt fixable.

[LROBBINS]

You fix by programming wont work because if it starts to move forwards even an inch and I dont want a turn that moves backwards or forwards then I will automatically correct that with my thumb!

Good point.

[Burgerman]

I also think that if invacare worldwide which is huge with massive budgets cant get brushless gearless motors working right after the 3rd major revision, then there is no way we are likely to get it right.

[Burgerman]

I also think that if the might of invacare worldwide which is huge with massive budgets cant get brushless gearless motors working right after the 3rd major revision in 14 years, then there is no way we are likely to get it right.

So geared brushless like William and the new guy whose name I cant remember is the only way. Which is a shame as the gear reduction is much of the efficiency loss/gains/noise.

[LROBBINS]

Eugene

[Burgerman]

Thank you! Yes I just took a look.

He seems enthusiastic! Although I suspect that the roboteq and sole dependence on it for a commercial operation may be problematic.

[Williamclark77]

My chair is *only* 270 pounds and I would still say the max user weight for it would be 200 pounds without some redesigning. I only weigh 135 pounds soaking wet. I could build it 40 pounds lighter, but it's tippy enough as is.

Who is Eugene and is there a link to his chair? I'd love to see it.

[Burgerman]

Heres his thread. viewtopic.php?f=4&t=7344

The website is a little worrying. Theres a lot of this sort of thing!

concept / vision

The story is important – vision is the key. The story of Cheelcare began with a vision, and then this vision became a reality.

Inspiration is what has formed our vision. For us inspiration has been coming from the rational beauty of natural creations.

Our team of talented inventors, engineers and designers are transforming the world into a better and inclusive world for all.

By sourcing beautiful solutions from nature and transforming those into assistive devices we help people with limited abilities to integrate in life, feel comfortable and independent. The beauty of our applications is the harmony of the design concept, in which design follows function and proves itself. On test stands, at home, at work, at school, outdoors.

As a team we have proved that we can create something unique. Cheelcare Xceed is no ordinary power wheelchair, but a modern multi-functional assistive device for everyday activity, whatever the challenge. It is an expression of freedom and a unique attitude to life. It is the reflection of human dignity.

Which doesent seem to say anything. Like they took a load of nice sounding artyfarty/ green/ natural sounding type of words and ran them through a blender. And the site is very light on actual info/detail. But lets wait and see what he actually makes. Looks a bit like a wide pram at the moment! I expect a lot will change. I hope it will... He is at least interested in input and wants to make something better.

[Williamclark77]

I never venture outside of the "Everything Powerchair" section, so I had not saw it.

I wish him the best. It's hard to tell much without real specs. I'm sure he's keeping a lot private and I don't blame him. It's not cheap or easy to develop one from scratch. I know too well!

At least he's actually doing something different. It looks interesting.