Fastest R-NET chair?

[emilevirus]

Looking for the fastest chair with R-net. Is the max 15km/h? I don't mind about low speed torque. It's for outdoors, mostly on road. I can't find anything that goes about 20kmh that drives with a joystick. Any suggestions?

[slomobile]

Embiggen your wheels.

[emilevirus]

Would a bounder be the best candidate for that? Would like some suspension as well. I'm tired of feeling every small bumps on the road.

[Burgerman]

Heres the problem. And why you cant find...
A 70A controller is ok at 4mph (6kph) motors. Even 2 pole weedy 6mph at a push. A 90/100A controller is OK for a 4 pole 6mph/7mph. 8mph needs 120A or more and lacks torque... You say it doesent matter and want to go faster. But when it refuses to turn in place, or you start a ramp and it wont go up it. Or you roll along a slight hill and the huge extra current causes the power module to warm up and roll back power and then the chair stops, Or it refuses to set off on a slope. And cant steer properly. What do you do? Thats what would happen if you wanted anywhere near the speeds you want.

And theres another issue. Even if we had say 160 or 180A power modules (we dont) then a lead battery of double the size (and weight) would also be needed. Not for range (although it would also need it for that as well!) but because of the amount of current draw. (Amps.) So that then adds a huge amount of weight... Which needs yet more amps, rinse and repeat...

Knowing all this I decided that the only solution would be to increase the voltage. (no mobility controller can do that other than a scooter one and have a guess why those can do 36 or 48V?). So thats when I started playing with the Roboteq controller.

So if I took some 8.5mph 4 pole motors, 24V and even a R-net 120A controller and test, you get a weak chair, low torque, and the 120A controller overheats easily. Not great but you can use it. Its horrible though.
So thats about the limit and not really advised even by the manufacturers who add notes about lower torque etc. Which you dont think matters. But it does! As you would find out very quickly. Would I ever buy an 8mph chair? (13kph.) Well it depends. If it had a load of heavy rehab seating? Nope. If I lived near a ramp or a hill? Nope! If I was any heavier than a ballerina? Nope...

However. If I wanted a simple chair, no heavy rehab options, used it with LITHIUM batteries, on level ground (no hills) and was a 13 year old girl (and I am not) then yes. 8mph.

But you want to double that speed. In order to do that you need double the voltage. Or you need 240A controller!
So I did it with a 45V lithium pack, on 8.5mph (13.5kph) motors. So that I doubled the speed.
To get adequate torque I used an 150A controller. (Volts = RPM. Amps = torque. In direct proportion.)
To get adequate speed I used a 45V 13S lithium battery.
So this:
26kph, 16 mph.
And I can tell you thats too fast and not workable with casters.
https://www.wheelchairdriver.com/BM-MK3 ... rchair.htm

But thats what it takes to go faster than 13kph. At least to make it work properly.

[fishinjunky]

Would a bounder be the best candidate for that? Would like some suspension as well. I'm tired of feeling every small bumps on the road.

The bounder can do 7mph with the high torque motors and 8.5mph with the low torque motors but like BM said not recommended.
If you put in a LiFePo4 battery it's lighter and slightly faster.

Most chairs are 6mph or 8.5mph

[Jay_x]

In the US 8.5 mph is the fastest any chair will go due to insurance policies. Anything faster and insuracne will not cover it therefore manufacturers do not make chairs that go any faster than 8.5 mph. Even Bounder stopped making their 12 - 13 mph chairs and now their top speed is 8.5.

I assume you are in the EU which generally has chairs that are slower than in the US. I doubt you will find a chair anywhere made in the EU that goes faster than 7 or 8 mph, so about 13 or 14 km/hr.

I have the Bounder that goes 12 - 13 mph. Its great, I lvoe it. the only issues is the battery drains real quick. If you put lithium on that old bounder that would be a great way to go.

[Jay_x]

Embiggen your wheels.

how does this help?

[emilevirus]

In the US 8.5 mph is the fastest any chair will go due to insurance policies. Anything faster and insuracne will not cover it therefore manufacturers do not make chairs that go any faster than 8.5 mph. Even Bounder stopped making their 12 - 13 mph chairs and now their top speed is 8.5.

I assume you are in the EU which generally has chairs that are slower than in the US. I doubt you will find a chair anywhere made in the EU that goes faster than 7 or 8 mph, so about 13 or 14 km/hr.

I have the Bounder that goes 12 - 13 mph. Its great, I lvoe it. the only issues is the battery drains real quick. If you put lithium on that old bounder that would be a great way to go.

I'd just buy these and put 230ah lithium. 12mph would be awesome

[emilevirus]

They dont sell in Canada. I'd need to find one up in US and import it. Any idea where to look to get a used one in US?

[Jay_x]

They dont sell in Canada. I'd need to find one up in US and import it. Any idea where to look to get a used one in US?

A used Bounder with the fast motors? Ebay is the only place really. You need to check repeatedly.

[Superchunk]

So I did it with a 45V lithium pack, on 8.5mph (13.5kph) motors. So that I doubled the speed.

Are you saying you can just feed more volts to stock wheelchair (permobil) motors for more speed and they'll be fine?

[Burgerman]

Well more or less yes.

But details matter.

The thing that hurts motors are basically 3 possibilities.

1. load. By which I mean current, Amps. The amount of amps a motor draws is directly related to torque. Load. So if they survive 120A - and they do as stock - and no gearbox or cush drive failures occur. So that as long as you still limit it to 120A max then they are physically strong enough. The RPM does not change anything here. So no damage from same torque as before. Amps = Torque in exact proportion.

2. Volts. You cant increase the volts beyond whatever it takes to make it pull the 120A limit. Because the controller puts a lid on this by reducing pulsewidth to make sure that never happens. So if you stall your chair against a wall then gun it the controller is limited to about 7V max as thats the point where the 120A limit occurs. Depending on motor impedance. As the chair speeds up, at max power, the motor which is also a generator too, starts to generate a voltage. So the controller then allows ever more volts to the motor while staying below its 120 LIMIT. So the only danger is that once you go above 24V the motor may physically fly apart. But I tested my 24V AMT motors on a power supply at 60V for 1 hour. Nothing flies apart. They draw around 5A free running, (NO LOAD so low current) and they dont get warm at all. So as long as you test at the RPM you want to run them + plus some extra just in case , then if they dont fail then no problem! Again, Volts = RPM in exact proportion. In the hobby world motors have no rated voltage. They are sold just as IMPEDANCE and RPM per VOLT.

3. So all good right? Well as long as you understand that at double the volts you get 4x the POWER then yes. Because doubling the voltage also means they will draw double the current. So if you were to run up a hill at twice the speed you did in the past, that you will be making a lot more power. That means more heat too. So up a hill if you dont use a little common sense you could burn them. If you understand this and use some common sense and just go fast on the flat then not an issue.

Watch this vid.
Its quite short. At the end I remove the seat, arms etc as I am messing with its settings. To test how fast it decelerates. Turn up the sound. You can hear how a 24V motor sounds with 4x the power! Like a motorcycle!

https://www.wheelchairdriver.com/gopro/RC-BM3.mp4

[Burgerman]

So I did it with a 45V lithium pack, on 8.5mph (13.5kph) motors. So that I doubled the speed.

Are you saying you can just feed more volts to stock wheelchair (permobil) motors for more speed and they'll be fine?

Yes and No. You can. But not with a mobility controller.
Thats is typically limited to around 21.xV in programming. Which you can raise a TINY BIT with lithium batteries. But thats limited to around 26V.

And mobility systems are DESIGNED around lead batteries. So that anything more tan say 2 volts higher than lead batteries and you will get an error, especially on "overun" when the regeneration current bumps the voltage up a bit as you slow down fast.

So you would need to do a custom system such as I did with the 50V capable Roboteq 150A per channel robotics controller. And that needs SERIOUS work and coding, current sensors, a one off purpose built joystick, wiring loom etc. And a LOT of configuration in the coding.

[Burgerman]

Embiggen your wheels.

how does this help?

It doesent. It makes the controller suck double the current to go twice as fast. But unfortunately also double the current at ALL other slower speeds. And limits torque to half. And halves range as it eats up battery power. Because of peukert this is worse than half the range.

That murders its controller and so it rolls back power (by stall current limiting and by only havng a few seconds boost, and by thermal roll back) very quickly. Also it means half the peak torque and so wont turn in place or climb a hill or a threshold. And the motors get overheated and die faster too as twice the current/power required at every speed.
You want to keep the SAME overall gearing as stock. That means stock wheel diameter and so same stock torque, same stock current (Amps) at every speed.

And instead double the voltage. So now at full stick 2x as fast! No downsides. And with stock current, no range reduction at all. The normal speeds, same torque and control as stock, no battery torture, no overheating motors or controller, no rollback of power. But twice the possible RPM (speed) so best of all worlds.

But that doesent work with any stock controller.

[emilevirus]

So I found a 10 years old Bounder for $1000US. Do you think it's worth it or too old?

[Burgerman]

The faster a bounder is the less torque and control. And the more it eats its battery. You will not be happy unless you know that first.

Age of a chair means nothing. It is quite possible for a chair to be 20 years old and as new. I have a couple of unused ones that are backups.
Or a year old and look like its been to war and found in a ditch. So it just depends.

You need to see it. And understand what you see. Mechanically, it depends on maintainance, such as drive chains... Those will probably need replacing regularly, so may be new or knackered and again depends on mainainance. So you cant really know.

[emilevirus]

I'll put 230Ah cells so range wont be an issue. Apparently they still do 10mph package but as addon.

[emilevirus]

They say the speed package requires Linx. Any idea why? They're both 120A. I'd rather R-NET as we have OEM access.

[Burgerman]

The linx system is identical in performance capability. But they likely went with it as its cheaper.
But terrible in regards programability if you are us. No access to OEM level programming. And if you do (and I do) its completely unfathomable! And doent work properly in windows either.
And so run away!

[emilevirus]

Here's their reply:

Hi Émile,

If you are outside the United States, then we can provide the Bounder at 11.6 mph. If in the United States then 8.5 mph is the top speed from the factory. In either case, the R-Net will not do with the high speed motors-you will be required to use the LinX electronics. You can use the R-Net for the ST4 motors with a top speed of 6 mph.

[Burgerman]

Nonsense!

120A is 120A

The R-Net is 120A for 10 secs. Then 100A.
The Dynamic system is 1sec at 120A and then 90A... As far as I remember.

Either way, faster than 8.5 mph is a terrible idea! I really dont like 8.5 mph chairs at 120A as they steer badly and have inadequate torque once you program the things to go, stop, steer in real time. Its a step too far. And they eat batts. So I always order 6.2 to 6.5 mph chairs now.

[Jay_x]

Here's their reply:

Hi Émile,

If you are outside the United States, then we can provide the Bounder at 11.6 mph. If in the United States then 8.5 mph is the top speed from the factory. In either case, the R-Net will not do with the high speed motors-you will be required to use the LinX electronics. You can use the R-Net for the ST4 motors with a top speed of 6 mph.

wow, so that is weird. Kind of dumb but there you have it. I had no idea.

[Jay_x]

Nonsense!

120A is 120A

The R-Net is 120A for 10 secs. Then 100A.
The Dynamic system is 1sec at 120A and then 90A... As far as I remember.

Either way, faster than 8.5 mph is a terrible idea! I really dont like 8.5 mph chairs at 120A as they steer badly and have inadequate torque once you program the things to go, stop, steer in real time. Its a step too far. So I always order 6.2 to 6.5 mph chairs now.

Nah the high speed chairs are great! I especially like going thru real smooth bike paths at full speed. Also gets me to the grocery store down the street and back nice and fast which is great when its freezing cold out. My bounder is currenlty dead and I really miss the speed

[Superchunk]

Also gets me to the grocery store down the street and back nice and fast which is great when its freezing cold out.

Oh my God, this is also a key motivator for me wanting more speed

[Burgerman]

Just tried to use the OEM version of the LiNX programmer to check IF the longest boost time can be upped from the 1 second. And I uninstalled it instead because the software is JUNK. I cant get it to work properly scrollbars missing, layout and structure is nonsensical and I couldnt get to the stuff I wanted to look at. RUN AWAY.

[Burgerman]

Nonsense!

120A is 120A

The R-Net is 120A for 10 secs. Then 100A.
The Dynamic system is 1sec at 120A and then 90A... As far as I remember.

Either way, faster than 8.5 mph is a terrible idea! I really dont like 8.5 mph chairs at 120A as they steer badly and have inadequate torque once you program the things to go, stop, steer in real time. Its a step too far. So I always order 6.2 to 6.5 mph chairs now.

Nah the high speed chairs are great! I especially like going thru real smooth bike paths at full speed. Also gets me to the grocery store down the street and back nice and fast which is great when its freezing cold out. My bounder is currenlty dead and I really miss the speed

You guys must all be driving around in chairs programmed for your grandmas!

[emilevirus]

Yeah, it'd be to use on road & bike paths. I only weigh 100lb so motors shouldnt struggle.
My Magic Extreme X8 has 10S lifepo4 and runs at 31v. Goes around 13kmh and it's super stable, could go even faster but R-Net won't take over 35v.

[Jay_x]

Nonsense!

120A is 120A

speed

You guys must all be driving around in chairs programmed for your grandmas!

what does programming have to do with it? Best programming in the world is not going to make my chair any faster

[Burgerman]

Well for a start the motor voltage on a stock R-net power module is usually set to 21.x volts. SOME allow this to be set as high as 26. Some (I didnt find one yet) can be set a little higher. This determines the actual speed the chair can go, at max stick! So you are wrong.
That only applies if the battery voltage is above this figure though. So with lithium you can increase it a little.

But that is NOT what I was talking about.

When a chair is programmed in grandma mode, hovercraft mode or whatever you like to call it like most chairs are, then the thing doesent respond to the stick directly. Everything is push, wait to see what happens. Especially turn rate acceleration and turn decellerations.
This then diguises the fact that the taller gearng or higher speeds (exactly the same thing) or inadequate controller power, or cheap / too small batteries no longer has adequate torque. Or contol. Because it no longer has ANYWAY because of the hovercraft steering! And so you wouldnt know or be able to feel it, directly or feel if things like motor load compensation is set correctly, or much else. Its all so vague that you cannot feel anything much. Or make a chair go where its told.

So when a chair IS set to follow the joystick, in real time, like a computer mouse or your cars steering wheel, you soon learn to expect the chair to do EXACTLY THAT! If it doesent then it feels like theres something very wrong. It feels as if you are flying a RC plane and some interference prevents control intermittently. It feels that at times of high load, the chair no longer does as you tell it. And its not only obvious its very frustrating and its dangerous. IF you are expecting it to respond as it should and it doesent or theres some delay you hit stuff! Break your feet. Or go off a curb.

This is why 100 to 120A is NEEDED for 6mph. At 12 mph you would need twice this for proper control. At EVERY speed. Because 12mph gearing draws double the current even at slow speeds. If you are happy driving around with no real control and have a chair programmed in granny mode you cant tell much difference until it stalls out on a ramp or something.

[emilevirus]

You can feel that when a lead acid is very low. It's very hard to steer, slow response. You almost hit a wall everytime. (I have crappy chinese batteries)

SOME allow this to be set as high as 26. Some (I didnt find one yet) can be set a little higher

Mine allows to be set to 31v. It's a Magic one. On my other chair it won't go past 25v. Probably limited in firmware.