However, there's a better way to go faster.
Just DOUBLE the working voltage, instead of increasing the gearing. This way at lower speeds nothing changes. You simple send the motors a lower voltage, and range, torque, etc remain the same. But you *can* send the motor more voltage!
This results in GAINS in torque due to higher Amp, and 45 Volts, (even more so than a HD bariatric chair) & also doubles the speed if you wish, all at the same time.
So instead of swapping speed for torque & range - you get EVERYTHING! And huge efficiency gains at the same time. You double the max speed without increasing Amp draw at lower speeds. You get to keep the cake AND eat it too! This seems like magic - its not.
The mobility industries standardised off the shelf 24v low power mobility controllers, and ancient lead batteries (they all use these parts for the past 15 years), simply don't allow this.
So I don't use any of them! There is no easy "over the counter"
plug and play solution that will give you a higher volt solution.
It requires a bit of work, robotics controllers,
some serious understanding of the physics involved.
Real World Measured! (ISO figures would be 75 miles! But thats rediculous)
Or up to 7 days of "normal" daily use between charges. Or about 3x better any 24v powerchair you can buy!
Forget the rest! This BM3 chair WILL get you there! And back.
EXISTING CHAIRS: 10 to 25 miles (based on the unrealistic ISO standard “tennis court” tests shown above). Real world usable range may be half to two thirds of this figure. So those 15 to 25 miles figures on the chart may not be achievable in any case!
Apart from being a flat course, it makes no account of the fact that the surface charge effect causes battery voltage to drop below the 18V typical "keep alive" point on a mobility controller at 60 to 70 percent discharged point. So this is seldom achievable. So the figures quoted by manufacturers is highly optimistic. My own figures are Real World measured so are what you will really get.
Range even with new batteries, on standard lead powered powerchairs, is completelyinadequate for many of us & you never know if you will make it back home again. Some of us live on hilly areas, or a long way from the shops, or are very active. It restricts the very places that you may attempt to travel to. Especially later in the day. If you are paralysed as I am the thought of running out of battery power before you make it home again is scary!
Fancy a night out? Not sure if you have enough battery left? Its a real worry and I personally can't ever get through a busy full day with a lead battery powered chair. So you just tend to choose not to try to go some places. Impacting your mobility.
Now there’s no need to worry, this BM3 chair has the equivalent stored power of 6 (SIX!) Group 24, 70Ah batteries! It just keeps going...
The world is big! And has hills! >>>
And this huge lithium battery is some 50+lb lighter than lead is, at the same time as being 3x more capable. Further helping range and performance, especially OFF road. You will always get home! This level of range FREES you mentally to get on with your life, instead of worrying about the damned batteries leaving you stranded somewhere. You can just forget about them.
3 times the initial cost of one single set of MK Gel 73Ah gel batteries. And is equal usable storage to 3 sets as well. So 3x as "big" a battery. So its either 3x the cost, or the same cost per mile of range, depending on how you look at things!
But in addition to giving 3x the range, it allows 3x the speed if implemented correctly, and approx 5x to 10x the service lifespan!
So no, its actually massively cheaper long term. With some truly huge advantages IF IMPLEMENTED CORRECTLY!
Break even point is about 3 years. if you ignore range and performance and service life. Its crazy to use lead.
Lithium batterieshave been this way for a decade. That's why your phone and laptop, drill, bike, strimmer, RC toys, and everything else uses Lithium already.
It really makes a difference! You will wear out first, long before the chair does!
MUCH of the gains possible are lost however at a lower 24v. So its not just a lithium battery solution. In other words you wouldn't get this range, speed, or lifespan just by fitting a lithium battery to your old 24v powerchair.
BM3 BATTERY: 300% greater energy storage than typical large Lead (Gel/AGM)
High 10C rate Nano Phosphate LiFePO4, 45v, with a massive 3240 Watt/hours of usable energy. With just HALF the weight of a set of lead batteries! And 10 to 15 year expected lifespan.
The equivalent stored power of 6x hi-end lead/gel/AGM 70Ah powerchair batteries. Charge on average twice a week gives 2000 cycles at 80% D.O.D. That's a 1000 week lifespan. Or a theoretical 19.2 years before range drops below 80%. Or 37 miles. This battery will outlive the chair and probably the user.
This isn't just any old lithium fitted for marketing reasons (as powerchair manufacturers will eventually do!) Its a high performance, low resistance, high C rate, massive 45V power pack!
EXISTING CHAIRS: Lead (gel/AGM) battery, 700 to 1100 Watt/Hours max usable capacity at the rate we use them in a powerchair. Or 1/3rd the storage capacity, but 2x the weight penalty if you prefer. That's pretty crap! Worse, you can watch performance decline monthly & have to replace the battery yearly because it requires charging daily... 300 to 500 cycles best case. It’s quite staggering that practically all industry standard powerchairs are still using terrible antiquated Lead based batteries in the 21st century.Or in some low volume cases where lithium batteries are in fact used, they are far too small capacity in comparison, or sticking to the industry standard 24v. In both these cases are in fact missing out on all the great efficiency gains and other longevity and range advantages they could have had but have not figured it out. But doing a great marketing job regardless... In this situations lithium offers little or no advantages.
This chair actually uses an old Sunrise F55s powerchair main tubular thin wall steel frame (in modified form). Because I liked it. And about six other insignificant components (also mostly modified) from the same chair too.
All of the rest, including all the important bits, positioning of wheels, different motors, Robotics control system etc, seat, battery, footplate and mountings, anti tips, CG, wheels, axles, every bolt and bracket is all totally different. About 90 percent of the metalwork here is hand fabricated or very modified. There is very little of this you could buy from sunrise medical that would fit at all, at least without some modification. 2 parts that are utilised are the seat back fabric and the rear light. But not its mountings, or bulbs, and it includes 2 Radio control receivers. And 90 percent of this chair has nothing whatever to do with Sunrise at all.
The complete chairs centre section is fabricated from scratch, the fabricated motor mountings now moved inboard to allow the better AMT motors to be used with wide soft riding high floatation tyres and still keep the chairs width narrow. Footplate and mountings are fabricated to allow it to move up and down with the modified seat frame front edge. This is mounted on rubber blocks shown here, allowing the casters to rise and fall on bumps, while the footplate and seat front remain static. So the users stays at the same pitch on uneven surfaces. Removing vibration from the casters over uneven surfaces.
Much of the rest is taken from other
disciplines in the case of wheels, tyres, control systems, batteries, e.g.
aerospace or automotive, hobby, and / or severely modified. Or is a one off
component made by hand. In other words there's no way to buy one! Every
important parameter in shape, position, C of G position and dimension, battery,
motor, control system on this powerchair is quite drastically different from the
chair that donated the round tube frame. Certainly only a very few parts could
fit without taking a hacksaw to it!
EXISTING CHAIRS: 8 Amp, 28.8v, 10 to 16 hours, dumb charger. And only at home, no data-log or testing capability or charging in a vehicle possible. Only one battery type or device.
Charging, controllable via PC and Bluetooth if you wish. Logs data, shows cell balance, Ah in/out and battery state and much more as it charges. Roboteq software allows for extensive programming and setup, configuration, logging to PC etc. And in real time during use. All way more advanced and more configurable and informative than the typical mobility product and free to download including updates, without restrictions or cost.
EXISTING CHAIRS: Heavily loaded often small casters sink on soft surfaces. Small width & cross section, harsh riding drive tyres also sink and transmit vibration. Causing discomfort, pressure sores & muscle spasm problems. Only work well on solid smooth surfaces e.g. shopping centres.
Inadequate speed, torque or accurate control for any practical real world outdoor use. Short battery range, gives no user confidence in going anywhere that is too far or is too difficult type of terrain such a hills or grass.
High floatation low pressure puncture proof tubeless tyres, lightly loaded large front casters, tons of power, huge battery capability make this sort of thing easy! Want to walk a dog up the beach? In the forest? Fields? Snow? Photo shows a friend in Thailand on holiday having fun.
Battery door at rear, 4 inches plus ground clearance, 5psi Kevlar reinforced K-Shield puncture proof tubeless tyres for smooth ride and floatation on soft ground, sand, snow. EVERY part show quality powder coated for protection against salt and corrosion. Including all fabricated centre section, motor mountings etc. No ugly rear overhang like production chairs means I can reverse my HEAD to a wall. This chair is just 37 inches long INCLUDING footplates and anti tips. Rear punctures on these special tyres are practically 100% impossible. Deflated FRONT tyre no problem! And no harsh riding skinny "flat free" tyres here! I can always get home.
EXISTING CHAIRS:Almost without exception use skinny harsh riding high pressure or foam filled 3.00 x 8 drive tyres. Or smaller. These transmit vibration and cause discomfort & spasm. They sink on soft surfaces, like wet fields, sand, snow. They are either tube (so suffer many punctures) or solid/foam filled (so called puncture free), which both eat battery power and give an even harsher ride.
For moving powerchairs around remotely, for service, cleaning, loading into vans, etc.
Switch transmitter on & automatically take over remotely! Maybe walk your dog?
High power RC capability built right in. DSMX Dual channel Frequency hopping, 3.2 watts RF output (boosted from original 100mW by some 32x) and with an AR10000 Receiver and 3 additional satellite receivers means accurate full safe Radio Control capability at up to 4 miles line of sight, and around a mile in and around buildings and cars. Just switch on, and take over at any time. Yes its safe to walk your dog. It cannot run away or lose control.
TOTAL 37 inches long including footplate and anti-tips. Shorter than all other powerchairs. No cushion fitted here. Low seat height. Allows for a thicker 3 or 4 inch deep (high risk) type cushions to be fitted without resulting in a high overall seat height.
Custom 45V high power control system and safety equipment lives below seat tray base. This is a custom control pod, made as small as possible with an APEM hall affect 5v swing joystick and controls to set max speed, RC ON/OFF, Power ON/OFF, etc. And status LEDs for battery, control mode etc. Pilot plus plastic shell only.
Roboteq controller, inverters, contactors, fuses, RC system, current sensors etc +other electronics, live "inside" the seat pan.
Battery: Safe, Lithium ion Phosphate (78 x 12Ah 10C cont. cells in 13x series and 6x parallel configuration). 43v nominal (46.8V charged). 45v nominal running voltage. 720A continuous current rated. 360A continuous charge capability. Given a large enough charger that is 5C or 12 minutes to fully charged is possible before damage.
Cycle life of 2000 cycles to 80% D.O.D. (1500 cycles even at 100 percent D.O.D). That's at least 5 times better cycle life than the best conventional gel or AGM lead based battery. And HALF the weight! Saving some 50lb! And since you need charge only every few days will last 10 to 15 times longer. (Equivalent usable stored energy to 6x group 24 lead batteries). Or 3x the usable energy storage capacity @ 3240 Watt/hours (compared to usable energy in a typical pair of group 24, 70Ah batteries at a high discharge rate). This pack would be at home in a small Electric Car!
Control System: Roboteq HDC2450 with 150 Amps per motor at 45V. Approx. 13,500 Watts electrical power capability for over 60 seconds. Almost 3x the power level of the mobility industries BEST offerings and for much longer before any thermal rollback occurs! Radio Control capability is built right in & full comprehensive PC control & data logging, graphing and battery, motor and controller real time monitoring capability + programming via PC and USB. Custom script/code for powerchair usage includes such things as motor compensation settings and other advanced control user settings. This controller is UNUSABLE without the script I use for control. And External current sensors to allow motor compensation to be utilised. Don't just go buying one thinking this is plug and play stuff. It will not be drivable!
Custom Joystick Pod Uses a Pilot Plus shell (its small and I had one!), custom switches, LEDs, Speed potentiometer and a replacement Hall Effect Joystick by APEM. This is much better suited to the Roboteq than the PG Drives ones for technical reasons. Custom loom, contactors, inverters for lower voltage brakes, lighting etc.
Speed: Nominal 15MPH or 24KPH (Actually about 16.4MPH measured speed via GPS)
Range: At least 45 Miles or 72 Kilometres real world on footpaths. More if calculated in the same way powerchair manufacturers do things. (The official ISO tennis court test) Or 15 miles+ of very unfriendly steep hills, beaches, off road use etc. About 3x what you will get from any other industry standard lead battery (AGM/Gel) powered powerchairs.
Ground clearance: 4 inches or 100mm (without tie down bolt - 2.5 inches with this installed).
Seat height: 16 inches at the rear, 17 inches at the front edge. Adjustable dump. Rehab seating also possible but may implement stability. Chassis mods recommended. Car style seats or other high/heavy seating not an option as they raise the G of G too high for good stability with the lightweight battery and short wheelbase.
Rear tyres: 145/70 - 6 (14.5 inches x 5.5 inches wide) low pressure tubeless 4 PSI high floatation for sand, off road, and comfort on the streets or off road! 4 ply, treated with off road puncture treatment. Best for ride comfort, snow, mud and keeping width below 25.5 inches. Wear very fast in summer.
Or: (Preferred option shown above) 15" (6.00 x 6) Kevlar lined puncture proof (turf tyres) for dry summer use. ALL tyres are tubeless, fitted to alloy tubeless polished aircraft rims. (Tubeless tyres are approx. 20x less prone to puncture deflation). And these Kevlar re-enforced and are PUNCTURE PROOF and last a very long time. They can be run at 5 to 6 PSI for best floatation and grip and offer a lot of vibration isolation.
Front casters: 3.00 x 4 tyres (9.7 inches x 3 inches) Treated with puncture seal. Powerchair can drive safely with a totally deflated front tyre due to rearward C of G (mass) position. And for the same reason these work on sand and snow too.
Width: including a 20 inch cushion, 25.4 to 26.4inches depending on rear tyres fitted. (All Terrain or Turf).
Length: Including footplate, anti-tips etc. 37.5 inches total! Shorter than all other powerchairs.
Charging: While mobile in a car or from the wall at up to 20 amps and 47v with an ultra-accurate automatic cell balancing Hyperion 1420i computerised 550 watt charger. Includes PC control, graphing, battery capacity measurement and IR resistance testing via PC.
Finish and durability: ALL bolts, nuts, washers, bearings, spacers, axles, from polished stainless steel. All other metal parts including hidden ones are heavy show quality gloss powder coated. Corrosion proof on our salty winter streets. All power and motor cables are high quality 10sq mm heavy gauge crimped and soldered. Built to shrug off corrosion and abuse.
Programming: PC based free to download, all possible options. This is a very technical programming tool that allows PC control, several different input control devices (including Radio Control) and logging information options in real time while in use on a laptop.
Motors: AMT 24V 8.5mph, 130Amp stall at 22V. Running on 45V so stall current up around 240 Amps, and RPM doubled to achieve 16+mph. Limited to 150A / 45v by Roboteq/software/ Custom script/code and external current sensors.
Lights: LED rear, LED bright driving lamp front.
Radio Control: JR 12X transmitter, converted to DSMX, and power output increased from RF out of 100mWatt to 3200mWatt. RC receiver is DSMX Spektrum AR10000 with 3 satellite DSMX additional receivers located in rear lights, seat back, seat tray front edge. Approx 4 miles line of sight range or at least half mile in and around vehicles and buildings. RX powered from Roboteq 5v directly, and 3 channels used. One for emergency RC switch to stop the chair via main battery contactor if required. 2 used for control. RX switched on off from control pod. Failsafe on encoded RF signal loss, stops chair fast.
Construction: www.wheelchairdriver.com/BM3-construction/ Folder of all sorts!Forum: www.wheelchairdriver.com/board/ Forum for questions on this chair or any others!
K Shield = puncture proof easy riding low pressure high floatation tyre. These work fine everywhere other than ice or really fine dry sand. And they will ALWAYS get you home!
Tubeless. Smoother riding, high floatation, works on grass, sand, snow, pavements and in the house and not mark if they are dry. Fatter tyres exert a lower pressure on the carpets and wooden floors. The opposite to the Stiletto heel affect. Same reason they float over soft ground and sand/snow with ease.
27" wide with these 6 inch wide Kevlar reinforced puncture proof turf tyres. -- OR -- 25.5" wide with the 145/70 - 6 all terrain tyres
WHAT'S THE PURPOSE OF THIS PAGE IF IF I DON'T SELL THESE POWERCHAIRS?
To embarrass the manufacturers into getting with the show, and doing some real development work instead of "colours", cup holders, and marketing hype. They are 15 years behind the rest of the non mobility world, 20 years behind the hobby world in technology and materials.
And to show other wheelchair users especially Paraplegics like me, what is actually possible on a tiny budget and to show how bad most powerchairs really are. As such there are others now building the "same" or similar, or modifying other powerchairs in one way or another. Many are members of my Message board.
What more does it need?
To the mainstream manufacturers:
Built by committee! If a cheap Chinese hobby model from eBay, a Lithium Brushless Carbon Fibre Quad-Copter as a typical example of technology (a drone), for a few hundred beer tokens, can have a solid state 6 axis accelerometer, 3 axis rate gyros, GPS, sensitive barometer for altitude measurements, electronic magnetic north compass, wireless PC connectivity, and fancy software that uses all this for better control and stability, send its pictures back 4 miles to my PC screen in flight, and use its own built in stability system & autopilot to fly my quad copter back blind for 4 miles to my house in a gale, ON ITS OWN! And land on my coffee table in my patio, what the hell have YOU guys actually been doing for the last 2 decades???
Cup holders? Colours? Lead batteries? Brushed motors? Weedy low amp, and low voltage controllers that we CANNOT be allowed to program properly for ourselves? (So they wont ever steer properly) we have had for decades... Tubed puncture prone tyres? Or heavy solid ones... Heavy rust prone steel construction to carry the overweight antique batteries? This stuff is 2 decades out of date. Don't get mad at me. Get your act together! I can do much better than this at home, working with few hand tools, in my bedroom as a paraplegic end user, with a total budget of HALF of one of your stock chairs. And a "team" of one. Doesn't seem like you are trying very hard.