Motorized chair manufacturers VS lithium

[Marcelo]

I don't understand why to this day manufacturers of motorized chairs don't use batteries
of lithium, would anyone know why this still happens today?

[Burgerman]

Yes. The manufacturers do not understand lithium adequately. And they also do not make aything. They buy in standardised parts, like control systems, wheels, bearings, motors, bolts, lights, actuators, etc. Then they make a frame to hold all the parts and sell it as a powerchair. They are not exactly advanced!

Lithium isnt a battery. Its a part of a system. You need to consider the motors, control systems, charge systems, C rates, and so on as a single unit. That is designed to work together in the way an electric car is.

Not a bunch of seperate universal parts. That may work with 2 standard lead bricks, but lithium doesent work that way. So they try and buy lead bricks but "lithium versions" that are plug and play. And that works very badly for a bunch of reasons.

[emilevirus]

But what about the new Permobil system? It now gives you the percentage and range left so it must have some kind of shunt inside the controller to calculate the draw and give you an estimated range/percentage. At this point, why not integrate a BMS and put Lithium batteries?

[Burgerman]

That isnt possible. Its programmers making up formulas to guess. They think lead batteries are like fuel tanks.

[Marcelo]

Yes. The manufacturers do not understand lithium adequately. And they also do not make aything. They buy in standardised parts, like control systems, wheels, bearings, motors, bolts, lights, actuators, etc. Then they make a frame to hold all the parts and sell it as a powerchair. They are not exactly advanced!

Lithium isnt a battery. Its a part of a system. You need to consider the motors, control systems, charge systems, C rates, and so on as a single unit. That is designed to work together in the way an electric car is.

Not a bunch of seperate universal parts. That may work with 2 standard lead bricks, but lithium doesent work that way. So they try and buy lead bricks but "lithium versions" that are plug and play. And that works very badly for a bunch of reasons.

They only think about making money, right? The last thing they think about is wheelchair users, right? But I think they're pretty stupid Because if they did it with lithium they'd make even more money, right, friend?

[Marcelo]

But what about the new Permobil system? It now gives you the percentage and range left so it must have some kind of shunt inside the controller to calculate the draw and give you an estimated range/percentage. At this point, why not integrate a BMS and put Lithium batteries?

I think they are very stupid Or very limited, right? Unfortunately, with so many electric cars coming out on the market, why not a motorized chair with lithium or a friend? That's very sad.

[emilevirus]

Here they say "fitting lithium batteries may void your warranty" https://www.magicmobility.com.au/servic ... questions/
But let's take their Extreme X8 for example. It's designed to go offroad, in snow, etc. But yesterday there was a lot of snow and I managed to take 130Ah out of my battery. That's more than 3x of what the lead bricks could offer. So Lithium is a MUST for this kind of chair but apparently it voids your warranty.

[Burgerman]

Because the AVERAGE user isnt on here. About 90% of disabled do a mile a day. Sit watching TV or drinking coffee or are say in an old folks home. And so they dont see the problem as a real problem. We are the odd ones. We are the problem. We dont fit the norm.

Add that to the way chairs are funded and bought. the vast majority are supplied to motability, a leasing charity in the UK or to the NHS and they do not ever have to compete in the world like the automitove and every other normal free market industry.

They dont need to keep making a better widget to sell their products. And they can charge whatever they want.

Tje lack of free market that drives inovation and pricing out in the real world of cars, lawnmowers, food, etc doesent really apply here. They are funded by that helicopter money and legislated and certified to death while the beurocratic bullshit decides what you will get.

Same reason they waited 10 years to get a used trabant 2 stroke or a moskacich car or a fridge in the state controlled socialist economy in the eastern block. Zero competitive market. Same reason that socialist everything, planed centrally controlled economies like venuzuala always fails.

If I made a perfect lithium wheelchair, it wouldnt sell. People in the US Canada, EU all get them "free" from insurace, the state, etc. And so you are not the one waving the cash. You are not the one they are trying to woo.

[Burgerman]

But yesterday there was a lot of snow and I managed to take 130Ah out of my battery. That's more than 3x of what the lead bricks could offer.

Thats 130Ah from a 244Ah battery? in that case and thats 6x more than lead bricks.
Or more realistically 5x more with a FULL SET OF LEAD BRICKS RANGE REMAINING for safe return!

And I think that the X8 doesent even have Grp24? Doesent it use bigger GRP 27/31 batts?
If so then you can get 300 Ah plus in it. Maybe not I dont have one.

Why dont the manufacturers do that? See post above... They SHOULD and its lighter too which saves more battery power! That thing is heavy, has 4 motors and tortures batteries.

[Burgerman]

OK heres a resna testing result from a large number of users from 5 years ago:

This is why they dont make chairs with any range. This was a study to see how much distance he AVERAGE chair user covers.

1.61 miles... That is almost definitely a bell curve. So anyone doing 3 miles is "extreme"... And they equate miles with battery state. I can kill a full set of batteries in 2 hours easily in a mile. 1 mile. By using a leaf blower tuning left right continually. Dead battery, never left my garden.

So when we say that a chair has 8 to 20 miles range, on resnas own "tests" (a very flawed gymnasium test anyway***) then they think that its way more battery than required.

The fact that a chair with decent agressive programming can kill a set of group 24 batteries in 2 hours while on bad terrain, or rolling at full speed, or leaf blowing the garden going back and forth never even occurs to them. Its so far from the average that its not even considered. So far from the norm that WE are now the problem. We are at the right end of the bell curve. Extremists!


*** They lap a oval marked on a smooth floor, do x number of laps at speed. They measure Ah used, and use the batteries 5h discharge rate capacity to calculate ultimate range. Why is that wrong? Constant speed is very low current. Its turning in place, cambered road edges and footpaths, or grass, carpets, and wiggling the joystick that eat much more power! And as a battery discharges its internal resistance goes up. And so its voltage drops off more under load. So when its 50% discharged the voltage drops below the threshold that the chair needs to stay ON. So you stop whth lots of power innaccessible.
They use the 5h rate for capacity. The much much lower 2 hour rate SHOULD be used and that still doesent take into account high current spikes as we climb or turn or accelerate. It just measures 7mph for 2 hours and 14 miles before we stop at constant current. So the resna range test given in a chairs specs will give a wildly optimistic miles expectation.

[emilevirus]

But yesterday there was a lot of snow and I managed to take 130Ah out of my battery. That's more than 3x of what the lead bricks could offer.

Thats 130Ah from a 244Ah battery? in that case and thats 6x more than lead bricks.
Or more realistically 5x more with a FULL SET OF LEAD BRICKS RANGE REMAINING for safe return!

And I think that the X8 doesent even have Grp24? Doesent it use bigger GRP 27/31 batts?
If so then you can get 300 Ah plus in it. Maybe not I dont have one.

Why dont the manufacturers do that? See post above... They SHOULD and its lighter too which saves more battery power! That thing is heavy, has 4 motors and tortures batteries.

New versions have grp 27 as of 2022. 2022 and under have grp 24. I had to cut out the battery box and make a new box because 230ah cells were 3mm too wide.
X8 pulls 45A just on flat surfaces! 80A going uphills. Over 100A when there's snow. There's no way a lead acid could last.

[Burgerman]

Thats because 4 motors, big low pressure tyres, and crap loads of weight.

Basically 2 fat tyre power wheelchairs. Rolled into 1. But that means it really needs twice the battery as well. One of the other things that those things do that really hammers the battery and causes the flip flop steering to be worse is this...

You want to turn (or just correct your path) so you add some turn input. Remember that rolling along in a straight like takes the least power. So now it adds more to BOTH motors on the left and less to both motors on the right.

The motor load compensation now sees the currennt rise as it tries to turn. It is supposed to do so, as to turn you add a little more volts on the outer wheels. And a little less on the inner wheels. Which increases current further. But because the rear drive wheels are effetively trapped in a straight line and outer one cant/dont turn faster the motor load compensation adds a crap load of extra power to try and make them turn. Why? Because compensation is just a bit of electronics that measures Amps and is quite sensitive. And is a positive feedback loop based on current. When it sees the extra turn Amps it then ADDS MORE. It does this as the outer rear wheel cant turn faster of course . So the outer one doesent naturally speed up in response to the extra turn voltage applied. So the controller bumps up the power! Rinse and repeat. The front outer ones, that were already free to turn now gets an extra boost of power too that you didnt command as its wired in parallel with the rear wheels...

So the front gets the result of the compensation that was applied to try and make the rear drive wheels turn. But realistically they cant! And the extra voltage diference they now recieve adds more current because they just cant turn... So then it adds more! It does all this "adding" by increasing the volts. And so current. Which turns the front wheels beyond what you were wanting.

So the result is that it steers like crap. And eats battery trying to force the rear to steer.

[Marcelo]

Here they say "fitting lithium batteries may void your warranty" https://www.magicmobility.com.au/servic ... questions/
But let's take their Extreme X8 for example. It's designed to go offroad, in snow, etc. But yesterday there was a lot of snow and I managed to take 130Ah out of my battery. That's more than 3x of what the lead bricks could offer. So Lithium is a MUST for this kind of chair but apparently it voids your warranty.

So do you use lithium in your Estreme X-8?
Would it be too risky for me to put lithium in my Permobil F5 and charge it via the joystick with the original charger itself?

[Marcelo]

Because the AVERAGE user isnt on here. About 90% of disabled do a mile a day. Sit watching TV or drinking coffee or are say in an old folks home. And so they dont see the problem as a real problem. We are the odd ones. We are the problem. We dont fit the norm.

Add that to the way chairs are funded and bought. the vast majority are supplied to motability, a leasing charity in the UK or to the NHS and they do not ever have to compete in the world like the automitove and every other normal free market industry.

They dont need to keep making a better widget to sell their products. And they can charge whatever they want.

Tje lack of free market that drives inovation and pricing out in the real world of cars, lawnmowers, food, etc doesent really apply here. They are funded by that helicopter money and legislated and certified to death while the beurocratic bullshit decides what you will get.

Same reason they waited 10 years to get a used trabant 2 stroke or a moskacich car or a fridge in the state controlled socialist economy in the eastern block. Zero competitive market. Same reason that socialist everything, planed centrally controlled economies like venuzuala always fails.

If I made a perfect lithium wheelchair, it wouldnt sell. People in the US Canada, EU all get them "free" from insurace, the state, etc. And so you are not the one waving the cash. You are not the one they are trying to woo.

You are absolutely right in this sense, considering that we are a grain of sand in the desert.

[Marcelo]

Thats because 4 motors, big low pressure tyres, and crap loads of weight.

Basically 2 fat tyre power wheelchairs. Rolled into 1. But that means it really needs twice the battery as well. One of the other things that those things do that really hammers the battery and causes the flip flop steering to be worse is this...

You want to turn (or just correct your path) so you add some turn input. Remember that rolling along in a straight like takes the least power. So now it adds more to BOTH motors on the left and less to both motors on the right.

The motor load compensation now sees the currennt rise as it tries to turn. It is supposed to do so, as to turn you add a little more volts on the outer wheels. And a little less on the inner wheels. Which increases current further. But because the rear drive wheels are effetively trapped in a straight line and outer one cant/dont turn faster the motor load compensation adds a crap load of extra power to try and make them turn. Why? Because compensation is just a bit of electronics that measures Amps and is quite sensitive. And is a positive feedback loop based on current. When it sees the extra turn Amps it then ADDS MORE. It does this as the outer rear wheel cant turn faster of course . So the outer one doesent naturally speed up in response to the extra turn voltage applied. So the controller bumps up the power! Rinse and repeat. The front outer ones, that were already free to turn now gets an extra boost of power too that you didnt command as its wired in parallel with the rear wheels...

So the front gets the result of the compensation that was applied to try and make the rear drive wheels turn. But realistically they cant! And the extra voltage diference they now recieve adds more current because they just cant turn... So then it adds more! It does all this "adding" by increasing the volts. And so current. Which turns the front wheels beyond what you were wanting.

So the result is that it steers like crap. And eats battery trying to force the rear to steer.

[Burgerman]

So do you use lithium in your Estreme X-8?
Would it be too risky for me to put lithium in my Permobil F5 and charge it via the joystick with the original charger itself?

He uses 8 x 230Ah cells, a BMS, and an external charger.

If you were to do the same, then an 8Amp mobility charger isnt a great idea but it would work. But lets say you wanted to replace 230Ah... Actually 244Ah (measured) then at 8A it will take 30 hours, plus a couple of hours at CV and balancing. So about 32 hours.

This is why in my chairs I use a 40A charge, no BMS and a cell balancing charger.

But I suspect that you wont understand any of this due to the translation problem!

[emilevirus]

In my other chair, I use some cheap Chinese 12v 100ah lifepo4 with a 10A charger.
https://www.aliexpress.com/item/1005003901983182.html

Works fine but goes out of balance so if you do, get a 24v battery not 2x 12v or you'll have to charge them separately every few months.

[Burgerman]

29.2V will cook them long term... But its needed with a BMS as its overvoltage helps drag the low cells up and adds a degree of self balancing to make up for the crappy balance that the BMS allows. Again thats why I use a hobby charger at 3.55V per cell, without the continued bouncing on off/up down. So a solid continuous 28.4V with no cell ever exceeding 3.550V.

[emilevirus]

29.2V will cook them long term... But its needed with a BMS as its overvoltage helps drag the low cells up and adds a degree of self balancing to make up for the crappy balance that the BMS allows. Again thats why I use a hobby charger at 3.55V per cell, without the continued bouncing on off/up down. So a solid continuous 28.4V with no cell ever exceeding 3.550V.

Well realistically, the wheelchair will be done before the batteries even when charged to 3.65v. I paid $150 for each so that's even cheaper than lead. Can't complain. Lasts about a week. Lead lasted a day, needed a charge everyday. After one year it was dead. It's my govt provided one and they use some crappy lead. I also need them to be easily swappable because I swap them before going to service it otherwise they'd freak out.

[Burgerman]

I would be facsinated to know what they service. I never serviced a chair in my life. Nothing to service!

Only to repair it if it fails or breaks. Or replace its tyres, when worn out. Its not like its got oil or air filters, valve clearances, fluids to replace, etc.

So short of just looking at it to see if it works, doesent make any funny noises, what can they do? They can do that in 30 secs at your house. It is another way to use the system to charge the insurance or user for something. A scam.

I used to do central geating systems in an earlier life.
I was asked to do the yearly service on gas boilers (furnace?) as almost every uk house is heated with one. Well I could do that. But I told most people that it was a scam. Theres nothing to service. You just waste some tme taking it apart, bang about for 20 mins, then put it back together for no good reason. If its working just carry on!

Of course the only time a chair really NEEDS servicing or rather proper configuration and preventitive "service" is when new.
CONFIGURE the thing properly on day one for the user. Takes 2 hours if lucky to several days to get right and may require dfferent parts or minor fabrication work. Grease every bolt, loctite safety ones, throw away steel bearings replace with stainless, grease all shafts and axles, spacers, etc, and route and fix/loosen all cables and loom as needed so nothing chafes or stretches or bends too tight in one spot, and spray protective elecsol or deoxit etc switch and connector cleaner into all connectors.

Then program it PROPERLY.

Throw away the charger and use a shirley zte zxd 2400 set correctly for battery type.

Then drive till it breaks or fails or makes a strange noise or whatever. Nothing to service.

[shirley_hkg]

Would it be too risky for me to put lithium in my Permobil F5 and charge it via the joystick with the original charger itself ?

I'd say it would induce unnecessary risks, if one didn't dare to jump out the comfort zone.

[Marcelo]

So do you use lithium in your Estreme X-8?
Would it be too risky for me to put lithium in my Permobil F5 and charge it via the joystick with the original charger itself?

He uses 8 x 230Ah cells, a BMS, and an external charger.

If you were to do the same, then an 8Amp mobility charger isnt a great idea but it would work. But lets say you wanted to replace 230Ah... Actually 244Ah (measured) then at 8A it will take 30 hours, plus a couple of hours at CV and balancing. So about 32 hours.

This is why in my chairs I use a 40A charge, no BMS and a cell balancing charger.

But I suspect that you wont understand any of this due to the translation problem!

I understand perfectly, burg man. In fact, I had already thought about that, right? Because charging at low amperages would take a long time, I completely agree with you on that. I would have to install an external charger, even in the 30 tamper range.

[Burgerman]

Well it depends.
Are we taliking about fitting 8x 244Ah cells, and having all the benefits of lithium?
In which case a powerful BALANCING charger is best.
Or at 2nd best a BMS and a powerful dumb charger.

But if you are taliking about some lead brick drop in replacement batteries then those are only going to be around 70 to 100 ah or they wont fit. In which case you dont get a real long life, or much extra range. But then you can charge with an 8A mobility charger...
But that basically misses out on the very reasons that we fit lithium batteries. A long lifespan, huge range etc. And it may be unreliable because of higher C rate discharge, deeper cycling and a BMS that do unspeakable things!

So what are we talking about here by lithium?

[emilevirus]

I would be facsinated to know what they service. I never serviced a chair in my life. Nothing to service!

Only to repair it if it fails or breaks. Or replace its tyres, when worn out. Its not like its got oil or air filters, valve clearances, fluids to replace, etc.

So short of just looking at it to see if it works, doesent make any funny noises, what can they do? They can do that in 30 secs at your house. It is another way to use the system to charge the insurance or user for something. A scam.

Then drive till it breaks or fails or makes a strange noise or whatever. Nothing to service.

By servicing I mean change tires, change motors, bearings, etc. Change cushions so happens every 2 years I'd say.

[Burgerman]

So you mean fix it...

I rebuild my chairs end to end and replace all parts subject to wear every 2 years roughly of USE. So if you have say 4 chairs, that means they all get worn out at 1/4 the speed. So not very often now. Once rebuilt they look, feel, smell, and are better than showroom. Because everything is refinished, replaced etc. Any part that can wear is thrown way. Any part that isnt, is refinished. And better bolts, stainless bearings, better tyres, bigger batts, lithium, new joystick, etc.

[emilevirus]

Well here we have winters and SALT. The frame just rusts like crazy after a few years. Same thing for cars. You won't see cars over 10 years old here unless they wash their car every ride which almost no one do. Wheelchairs are even worse because they use low quality metal/aluminum.

[emilevirus]

Well it depends.
Are we taliking about fitting 8x 244Ah cells, and having all the benefits of lithium?
In which case a powerful BALANCING charger is best.
Or at 2nd best a BMS and a powerful dumb charger.

But if you are taliking about some lead brick drop in replacement batteries then those are only going to be around 70 to 100 ah or they wont fit. In which case you dont get a real long life, or much extra range. But then you can charge with an 8A mobility charger...
But that basically misses out on the very reasons that we fit lithium batteries. A long lifespan, huge range etc. And it may be unreliable because of higher C rate discharge, deeper cycling and a BMS that do unspeakable things!

So what are we talking about here by lithium?

I configured my BMS to stop charging at 3.43v and once in a while I increase it just to get it balanced properly. With a 100Ah you still get 2x the range and they're cheaper than lead so it's hard to say no. Also, BMS keep getting better and better. BT BMS are pretty good. I've had 0 issues with mine so far. It's not as good as a DIY 230ah one but if someone isn't tinkerer, it's still an upgrade over a lead brick.

[Burgerman]

Again it depends on a bunch of things.
If your chair is programmed agressively and you drive it like you stole it the typical lead brick keeps of tripping out as the BMS see intermittent high currents, or low cell voltage under load etc. And then we have get back home issues. We had a guy that dis all of that called nandol on here and he was repetedly rescued.

We also had a guy whose name I forget that had internal construction issues that made it keep tripping out. And I myself programmed a guys chair and that made it start acting up. Because now the chair actually responded! The battery couldnt.

So...

You may be lucky or not.
And it will likely be OK if the chair is programmed in grandma mode, or hovercraft mode as I call it, or if you are light, or if its a weedy controller of motors, or if its not a heavy rehab chair thats around 190kG withou a user. But dont count on ot being a reliable fix if you are several of the above.
But then I also blow fuses and make tripswitches pop too. But thats easy to fix with a heavier fuse. But the cells themselves dont like it either if like nandol you wire the chair to run direct from the cells and bypass the BMS. So it can work, it depends on a bunch of things. Inc the quality (internal resistance) of the cells used, the weights, programming, motor speed, controller capability, user mentality and expectation, BMS fitted, etc etc.

So as long as you understand that stuff, you may well be fine. But just dont count on it. Many tried. Some seem OK, some others not so much!

[Burgerman]

Well here we have winters and SALT. The frame just rusts like crazy after a few years. Same thing for cars. You won't see cars over 10 years old here unless they wash their car every ride which almost no one do. Wheelchairs are even worse because they use low quality metal/aluminum.

Really, I would have to move. Last night 0 to 1C and 9C today. Thats way too cold already!

[emilevirus]

Again it depends on a bunch of things.
If your chair is programmed agressively and you drive it like you stole it the typical lead brick keeps of tripping out as the BMS see intermittent high currents, or low cell voltage under load etc. And then we have get back home issues. We had a guy that dis all of that called nandol on here and he was repetedly rescued.

We also had a guy whose name I forget that had internal construction issues that made it keep tripping out. And I myself programmed a guys chair and that made it start acting up. Because now the chair actually responded! The battery couldnt.

So...

You may be lucky or not.
And it will likely be OK if the chair is programmed in grandma mode, or hovercraft mode as I call it, or if you are light, or if its a weedy controller of motors, or if its not a heavy rehab chair thats around 190kG withou a user. But dont count on ot being a reliable fix if you are several of the above.
But then I also blow fuses and make tripswitches pop too. But thats easy to fix with a heavier fuse. But the cells themselves dont like it either if like nandol you wire the chair to run direct from the cells and bypass the BMS. So it can work, it depends on a bunch of things. Inc the quality (internal resistance) of the cells used, the weights, programming, motor speed, controller capability, user mentality and expectation, BMS fitted, etc etc.

So as long as you understand that stuff, you may well be fine. But just dont count on it. Many tried. Some seem OK, some others not so much!

Mine pops wheelies everything set to 100%. Of course you need to understand. Usually BMS specs are listed under the listing. Take 150A continuous and it'll be fine. Mine is 100A but 200A peak for 30s. It never tripped even when I hooked a motorcycle to my wheelchair to try to start it, battery was dead. (Voltage did go down, I lost 2 bars on my joystick.)