low speed, high torque motor and Ligo battery choice help

[Amber]

Hi,
I am trying to power my own DIY mobility trike made out of bike parts (delta trike shape) as I cannot find one with off road capability e.g. forests, mud, tree roots, rocks, camber. That had suspension or the ability to climb steep hills. For use in cities, galleries, festivals and countryside national park hikes so I don't have to choose between city only or a walk e.tc. I could do with some advice on parts please, particularly motors and batteries.

I thought I could use;
-A twist grip throttle.
-A Reverse switch
-A display. Cycle Analyst V3 from Grin? To select the speed level. Speed levels selection of 4mph (6.4kph) for pavements, 8mph for road use and a max of 12mph (19.31 kmph so I don't tip over) 15.5mph is the speed limit for UK e-bikes.
-I will be relying completely on the motor for power. (No pedals, bike gears e.t.c.).
-bike hydraulic disk brakes.
-16 to 20inch wheels ideally, 24 inch max. 20inch sounds best for potholes/rough terrain
-front and rear lights
-I assume the Phaserunner controller is best. Program the reverse speed and not have a twitchy throttle. (https://ebikes.ca/product-info/grin-products/phaserunner.html)
- 6 LiGo plus batteries (https://ebikes.ca/product-info/grin-products/ligo-batteries.html)
-A motor or dual motors. (rear or side mounted).
-Satiator-so I can charge the batteries anywhere in the world without worrying about having the wrong plug socket output and damaging the charger/battery?
-temperature sensor- to reduce the risk of me damaging the motor.

Motor options-
I am assuming the smallest wheel size with good torque at low speed would be a 20inch wheel rather than a wheel smaller than this?.
To have the option of reverse requires either a direct drive motor, or a geared motor with a locked clutch.

In terms of torque, does anyone know much does the grin all axle and the GMAC Hub Motor give? I couldn't see it on the site.

The Grin All-Axle Hub Motor is available as a front hub (rear hub version is under development) so you'd be looking to do a either a single side or, for more power and traction, a dual motor setup. https://ebikes.ca/product-info/grin-products/all-axle-hub-motor.html

A rear hub like the GMAC, a geared motor with a locked clutch. https://ebikes.ca/product-info/grin-kits/gmac.html

Or Heinzmann Cargo Power system (front, rear or side mounted) depending on if I can use Ligo batteries with it (different connectors) or if their battery is ok in terms of airline requirement (see below). Heinzmann says it has a Rated load torque: up to 31 Nm (but only 11.9Nm at 250W, at 36V or 48V) and can push a 300kg load up a 10% incline. The following batteries are supported by the Heinzmann software: - SBS UniPower 14S12P INR18650 35E Weipu WY28K8BZZ 48 V - GPMES GreenPack Li-I 003 14s10p 48 V - AES bicycle battery 36V/16,5Ah LiFePO4 26650 11s5p - BMZ Battery Heavy Duty 27670-00 10s7p 36 V Other batteries (36V or 48V) can be used as well but will not communicate with the software. HIGO battery connector. https://www.heinzmann-electric-motors.com/en/system-solutions/bicycle-drive-systems/cargopower.

"Areas where the bike is moving at lowish speeds through high resistance terrain, and the mid-motor in an easy gearing will do this with better efficiency than most hubs drives, while still performing just as well on the faster roads". I considered a Bafang® BBS01B-ETMh, with a peak of 100Nm, 36V, 250W, with a throttle, however, a mid-drive motor will not let me have a reverse direction. https://www.brightonebikes.co.uk/store/p112/Bafang%C2%AE_BBS01B-ETM_36V_250W_motor_kit_%28DPC-18_display%29_with_LG_MH1_cell_16Ah_downtube_battery.html

For off road terrain and hills would a single rear motor or two side mounted motors be best for torque and for the motor to not get damaged by the demand? If one motor is best I will mount the motor at the rear, in the centre, for better traction. I have found that a single front motor slips on hills here as I am not heavy enough (50kg).

Battery
I will use Grin LiGo batteries as I need to be able to separate them for airlines to meet the limit of two 300Wh lithium ion batteries for mobility scooters on a plane. I could therefore connect 6 LiGo batteries together when using the trike. Most walks I do are 21km or more. There is one I would like to do that is Distance: 8 miles, 12.9km (there and back) Total Climb: 1,015m (3,330 ft). Trike/wheelchair is 20kg (no motor/battery). I am 50kg. Would I use one 600Wh battery to one hub motor or would one 600Wh battery to two motors do an OK ride distance on hills and off-road terrain and as the battery ages and has less capacity, if using two motors worked best in this terrain/demand?

If was was solely under throttle power and not putting any human power into a ride, what size battery would you recommend for offroad/hills? I don't know how to calculate how draining this situation would be for the battery using just a twist grip throttle.

Due to this battery limit I thought that having just one motor could be best in terms of having a longer battery life per trip compared to two side mounted grin motors or two rear motors running off that set up? Is that assumption correct?
If I had dual motors would I need to double the batteries in terms of getting the same distance or would one 600Wh battery manage a day trip (steep hills and off-road terrain)?



Ligo battery information
Nominal Voltage 36.0 V
Nominal Pack Capacity 2.7 Ah (2.75 for LiGo+)
Nominal Pack Energy 98 Wh (99Wh for LiGo+)
Dimensions 201 x 74 x21 mm
Weight 610 g (1.3lb)
Connector(s) Anderson
Can be series stacked for 72V without issue
3 Parallel LiGo (~300 Wh) heavy use range 18-22 km https://ebikes.ca/getting-started/battery-options.html

general battery info
Power Hungry (either no pedalling, or hauling a load, or going really fast). 14-20 Wh/km rough energy usage.
take your trip distance, multiply it by the appropriate watt-hours/km from the table above, and you'll get the total minimum watt-hours required for the trip. Take the watt-hours you've estimated and divide it by the voltage, and you now have an estimate on the minimum amp-hours you'll need from the pack.
For even more information you can consult the motor simulator to see how your setup will fare in the real world.
https://ebikes.ca/learn/batteries.html


Optional parts for a 2wd design
the simplest solution for a 2WD system might be:
2 motors with a similar winding
2 of the same controllers
One throttle - split the power 50/50 to the controllers. splitter cable: https://www.ebikes.ca/shop/electric-bicycle-parts/wiring/ca3-wp-dual-controller-splitter.html
One or two batteries

Thank you for your time, thoughts and help.

 

[amberwolf]

to determine torque amounts for those motors you can use the http://ebikes.ca/tools/simulator.html and put your proposed setup in there, to see what you get under various conditions.

regarding wheelsize vs torque, the smaller the wheel (for a hubmotor) the higher the torque but the lower the speed. (this is part of why you may not see torque values listed for just a bare motor, but might see it for a motor in a wheel).

if you put a tire on the motor's spoke flanges it would have the highest torque possible for the given setup, but it would be a terrible ride on anything other than perfect pavement. if you want a better ride, especially under poor road or path conditions, use the largest diameter wheels and tires you can practically fit, with the most air volume. (even if you have suspension, you'll still get a better ride).


regarding power usage, you can also use the motor simulator and trip simulator to determine wh/mile under various conditions. for "steep hills" you might use dozens of wh/mile, dependign on slope, road conditions, weight, etc. for completely flat paved roads you will probably use a dozen wh/mile or less.

two motors (as two independent systems) gives redundancy, since you have no human powered drivetrain you will be stuck where you are if you have only one motor and something goes wrong. it doesn't typically significantly affect power usage (it is a little higher as the extra weight of the second system takes more energy to accelerate and to climb hills), except under the cases where a single motor system would be limited in total power to much less than a dual motor system, and you use that extra power in acceleration and/or hill climbing for significant times/distances.

i do recommend using not similar windings, but the *same* winding of the *same* motor, or else they won't share power very well, if at all, without significant tuning of the system to put more throttle on the slower-winding motor throughout the speed range of the system under all usage conditions to ensure matching output of each.



btw, unless you use very small wheels, then for your slow speeds you might as well just use the batteries all in parallel, not in series. if you use them at higher voltages then you will be more severely restricting the controller to prevent higher voltages on the motor so it doesn't go too fast; otherwise at higher throttle values the motor will push you too fast on flat roads. plus, in parallel the batteries can provide more current, and be better able to supply the controller with what it will need on the hills. note that for some controllers that do current-control (like the phaserunner, etc) this may not be the case; it may not matter which way you wire the batteries, the system performance may be the same. the motor simulator may help you determine this if you experiment with varying conditions that match your realworld usage needs.




you can setup the ca itself to not have a twitchy throttle (rather than having to use the phaserunner, though the pr can also help with this), and you can use a cable-operated throttle unit rather than one built into the handlebar control for finer control and better weatherproofing, etc. then you can also experiment with different hand control mechanisms (trigger, grip, thumb, etc) to find the best match for your abilities, without affecting the actual electronics of the throttle itself.

 

[Chalo]

I am trying to power my own DIY mobility trike made out of bike parts (delta trike shape) as I cannot find one with off road capability e.g. forests, mud, tree roots, rocks, camber. That had suspension or the ability to climb steep hills.

Trikes turn over easily, especially when the ride height is tall compared to the track width. Suspension makes them turn over more easily, because it compresses on the downhill side and extends on the uphill side. What you're proposing seems like a serious fall hazard unless either you're sitting quite low in the trike, or the track width is very wide, like a car's.

If you want to get the seat low in the trike, delta layout doesn't work as well as tadpole layout.

If you have the physical ability to ride a two-wheeler, understand that it will be much more competent in the conditions you describe, because you can ride cambered ground without tilting.

The Grin Bafang wheelbarrow motor is a much better match to the capabilities you have outlined than any of the motors you mentioned.
https://ebikes.ca/shop/electric-bicycle-parts/motors/geared-wheelbarrow-motor-with-tire.html

 

[amberwolf]

Trikes turn over easily, especially when the ride height is tall compared to the track width. Suspension makes them turn over more easily, because it compresses on the downhill side and extends on the uphill side.

isn't there a cross-linked suspension method that can help prevent this? might require mechanical (or electronic) "smarts"....but i thought i had seen something like this when i researched suspension systems back when i was trying to come up with a cargo trike design years back (before i decided to just skip suspension to get greater cargo space and lower cg))

 

[ColinB]

Have you checked out what others are doing?

ie: https://notawheelchair.com/
Several videos about it, https://www.youtube.com/watch?v=vuMg0QwKAGI, so should show motors, speeds, etc.

I know building it yourself is part of the fun, but you might get some ideas.

Battery size is hard. You want them small, to save $, space, weight. But you also want them large, to have range, and to increase rated power handling. (So you don't have to run the battery at, or above, their rated limits. Since makers might be a bit optimistic.)

 

[Amber]

Have you checked out what others are doing?

ie: https://notawheelchair.com/
Several videos about it, https://www.youtube.com/watch?v=vuMg0QwKAGI, so should show motors, speeds, etc.

I know building it yourself is part of the fun, but you might get some ideas.

Battery size is hard. You want them small, to save $, space, weight. But you also want them large, to have range, and to increase rated power handling. (So you don't have to run the battery at, or above, their rated limits. Since makers might be a bit optimistic.)

Hi,
Thank you for your reply. Yes I've had a look around e.g. Bowhead corp, Boma 7 and the one you came across.

Yes it is the battery that concerns me as if I cannot get the range needed from them due to the airport restrictions on batteries then that will inform some choices I make.

 

[Amber]

to determine torque amounts for those motors you can use the http://ebikes.ca/tools/simulator.html and put your proposed setup in there, to see what you get under various conditions.

regarding wheelsize vs torque, the smaller the wheel (for a hubmotor) the higher the torque but the lower the speed. (this is part of why you may not see torque values listed for just a bare motor, but might see it for a motor in a wheel).

if you put a tire on the motor's spoke flanges it would have the highest torque possible for the given setup, but it would be a terrible ride on anything other than perfect pavement. if you want a better ride, especially under poor road or path conditions, use the largest diameter wheels and tires you can practically fit, with the most air volume. (even if you have suspension, you'll still get a better ride).


regarding power usage, you can also use the motor simulator and trip simulator to determine wh/mile under various conditions. for "steep hills" you might use dozens of wh/mile, dependign on slope, road conditions, weight, etc. for completely flat paved roads you will probably use a dozen wh/mile or less.

two motors (as two independent systems) gives redundancy, since you have no human powered drivetrain you will be stuck where you are if you have only one motor and something goes wrong. it doesn't typically significantly affect power usage (it is a little higher as the extra weight of the second system takes more energy to accelerate and to climb hills), except under the cases where a single motor system would be limited in total power to much less than a dual motor system, and you use that extra power in acceleration and/or hill climbing for significant times/distances.

i do recommend using not similar windings, but the *same* winding of the *same* motor, or else they won't share power very well, if at all, without significant tuning of the system to put more throttle on the slower-winding motor throughout the speed range of the system under all usage conditions to ensure matching output of each.



btw, unless you use very small wheels, then for your slow speeds you might as well just use the batteries all in parallel, not in series. if you use them at higher voltages then you will be more severely restricting the controller to prevent higher voltages on the motor so it doesn't go too fast; otherwise at higher throttle values the motor will push you too fast on flat roads. plus, in parallel the batteries can provide more current, and be better able to supply the controller with what it will need on the hills. note that for some controllers that do current-control (like the phaserunner, etc) this may not be the case; it may not matter which way you wire the batteries, the system performance may be the same. the motor simulator may help you determine this if you experiment with varying conditions that match your realworld usage needs.




you can setup the ca itself to not have a twitchy throttle (rather than having to use the phaserunner, though the pr can also help with this), and you can use a cable-operated throttle unit rather than one built into the handlebar control for finer control and better weatherproofing, etc. then you can also experiment with different hand control mechanisms (trigger, grip, thumb, etc) to find the best match for your abilities, without affecting the actual electronics of the throttle itself.

Hi,

Thank you for your reply.
I have tried out the motor simulator. I was wondering when you add two systems together how to best represent the batteries for the following. System A and system B with the exact same motor to replicate two motors running off one 6 block of ligo batteries. I had to have it as 3 ligo batteries on system A and 3 on system B. Is that how it would work/ be represented in the simulator because one motor doesn't have access to 6 ligo battereis, it is sharing it?


What does ca stand for when you talk about "you can setup the ca itself to not have a twitchy throttle".

 

[Amber]

[/quote]
isn't there a cross-linked suspension method that can help prevent this?
[/quote]

Is cross-linked suspension, double wish bone suspension?
http://www.kolltek.com/#:~:text=Cross%20Link%20provides%20anti%2Droll,affecting%20just%20a%20single%20tire

 

[Amber]

Trikes turn over easily, especially when the ride height is tall compared to the track width. Suspension makes them turn over more easily, because it compresses on the downhill side and extends on the uphill side. What you're proposing seems like a serious fall hazard unless either you're sitting quite low in the trike, or the track width is very wide, like a car's.

Hi,
Thank you for your reply. I am aware that I need to use a low seat height and/or a wide track width. I cannot ride a normal bike currently.
I did wonder about the Grin Bafang wheelbarrow motor but it is very loud.

Currently I am just trying to work out if the airport restriction imposed on lithium ion batteries to carrying only two 300Wh batteries will make this project impossible or not even if I did use 6 Ligo batteries which can then be broken down into two 300Wh batteries for the airport. Whether 6 ligo batteries would put too much limit on distance or not. Whether the battery limits then having an influence on motor choice or one motor vs two of the same motors. Lastly if the motor set up and motor choice works OK under the terrain/hills e.g. torque levels, not overheating. If it can't do the terrain and distance due to this then I will need to think.

 

[amberwolf]

I have tried out the motor simulator. I was wondering when you add two systems together how to best represent the batteries for the following. System A and system B with the exact same motor to replicate two motors running off one 6 block of ligo batteries. I had to have it as 3 ligo batteries on system A and 3 on system B. Is that how it would work/ be represented in the simulator because one motor doesn't have access to 6 ligo battereis, it is sharing it?

From the instructions below the simulator:

Dual Motor Systems
With System 'B' open, you also have the option to add the output power of the two setups (A and B) to simulate a dual motor drive on a single vehicle. Appropriate fields will be greyed out, so you only have one vehicle to model. Note as well that the two systems each require their own battery pack, it does not model dual drives pulling energy from a single battery.

So I guess the way you did it is the way it would need to work (assuming that the workload is always evenly shared between the motors, then the motor load is shared evenly between the batteries, and they should then simulate the same way they would operate as if they were one big pack).

What does ca stand for when you talk about "you can setup the ca itself to not have a twitchy throttle".

Cycle Analyst (you'd already picked this in your original post for speed level selection). If you read thru the whole CAv3 info page on grin's site, it shows all of the menus and what you can set things to (and there is also a separate manual, and even better there are videos by Justin about how things work, all on that same page). It's a pretty complicated device, and if you are willing to take the time to learn it and set everything up in it and tune it to your needs, it can do nearly anything you would like to happen regarding limiting/tuning the response of a controller/motor system to a throttle (or other sensor(s)) input. Not quite perfect, but it is pretty good.

Best used with "dumb" controllers that don't do their own throttle response tuning / limiting, etc., so the two systems dont' interfere with each other unpredictably. If you use a controller that also has a feature the CA does, then you should disable the feature in whichever one you're not using for that, or you may not be able to reliably predict how it will respond while riding it.

 

[amberwolf]

Currently I am just trying to work out if the airport restriction imposed on lithium ion batteries to carrying only two 300Wh batteries will make this project impossible or not even if I did use 6 Ligo batteries which can then be broken down into two 300Wh batteries for the airport. Whether 6 ligo batteries would put too much limit on distance or not. Whether the battery limits then having an influence on motor choice or one motor vs two of the same motors. Lastly if the motor set up and motor choice works OK under the terrain/hills e.g. torque levels, not overheating. If it can't do the terrain and distance due to this then I will need to think.

You'll need to figure out how much power it will actually take to move you at the speeds you want on the terrain you want. That's where the simulator (motor and trip) can help give you guesstimates, that you can then round upwards.

Once you know the watts you need, you can guesstimate the time you need those watts for, which gives you watt hours (wh), which is then used to determine how big a battery you have to have to get the range you need.

For flat terrain it's a pretty straightforward figuring; generally for a given bike/trike configuration it's a straight watts-at-speed number, then just multiplied by time. But it sounds like you have quite a lot of varied terrain, so you will have to work out how much of what slopes at what speed you have, and for how long on each one, to get the wh needed for each trip segment. Then add those all up to get the minimum wh required, not counting problems, detours, wind, worse path conditions than expected, etc., for which you would need to also make allowances.

I'd also recommend leaving some extra wh in there to keep a phone charger powered, so you can recharge your phone if necessary to be able to call for emergency transport in the cases where your system simply is unable to get you out of a situation for whatever reason. (since you aren't intending to have any human-powered portion of the vehicle, you wouldn't have any way to ride it without the motor system working; even if you did have human power drivetrain, if you yourself can't power it, you're still stuck).