Throttle speed at 200w for Grin All axle hub motor

[simplydata]

Hi! I have installed a standard speed all axle hub motor for my 20in recumbent trike just last weekend. Currently, I am getting 13 mph max at 200w with throttle only. This speed is 3 mph slower than my RH212 I had before. If anyone have the same motor on their trike, please let me know if you are getting the same result. The battery is 48v.Thanks

 

[E-HP]

Do you know the windings for the two motors? You can model them in the grin simulator to see if the motors show the same speed difference.

 

[neptronix]

That's a lot less than i'd expect:

Motor Simulator - Tools

 

[simplydata]

I've wanted to put dual hub motors on a recumbent trike ever since Grin announced the single-sided All Axle and I read ecat's build thread. It's a pricey undertaking so I decided to split this project into 2 phases: (1) try a single front motor, then (2) buy a second if it works out.

Phase I is complete, using this pre-2013 Catrike Expedition as a host. I installed the GAA on the left side along with a CA3 and tucked a Phaserunner V6 under the seat.

View attachment 357195
Now you are probably thinking, "how the heck does that handle?!" Surprisingly well. You can feel the motor pulling during acceleration or braking but it doesn't cause the trike to veer much,as the other wheel pulls it back to center. The standard wind (6T) All-Axle has sufficient torque to squeal the tire when applying full power from a stop; 20" really is the sweet spot for a direct-drive hub motor. I'm watching the left spindle carefully for any signs of play; this was an issue on ecat's trike.

I carried over my 52v 18ah battery with Molicel P45s from Bicycle Motor Works and get ~ 50 miles per charge with a top speed of 28 mph and generous throttle use. The pack fits right into the cruciform. If I feel like wrestling the cranks, I'll swap in an ERider T9 torque sensor. Before moving onto Phase II I need to tame the bumps - the previous owner installed a skinny 700c wheel but that's not gonna cut it for ThunderCat. I think a proper 26" wheel with a Big Ben tire will help.
View attachment 357196

Hi! Do you possibly know how fast you can go at 200w using throttle only. My rear axle ,motor is giving me 13mph at the max. I feel this number is too low.. Thanks

 

[neptronix]

Very few DD motors operate efficiently at super low speeds. That motor is designed for 1000w continuous.

You probably want a small geared hub motor.
Use grin's motor simulator for a guide on what motor is most efficient at such a low power range.

 

[simplydata]

Do you know the windings for the two motors? You can model them in the grin simulator to see if the motors show the same speed difference.

The tool is showing 21 mph for RH212 and 22 mph All axle using Full Recumbent. I believe both motor should have similar value.

 

[neptronix]

Can we get a good picture of your trike?

 

[E-HP]

Looks pretty even to me (assuming 200W battery)

 

[amberwolf]

Hi! Do you possibly know how fast you can go at 200w using throttle only.

Depends on your terrain, hills, winds, road conditions, tire inflation/rolling resistance, system voltage, motor kV (RPM/volt), how your controller responds to throttle, any controller limitations, what assist mode / level it is in and what those are setup as, etc.

My rear axle ,motor is giving me 13mph at the max. I feel this number is too low.. Thanks

Which version of the Grin All Axle motor are you using? (presumably that's the motor you're using as that is what this thread is for, that you are posting to)

Which specific controller are you using?

How is the controller setup? (what settings are you using?)

What battery voltage are you using?

Which specific battery are you using?

What are your terrain, road, wind conditions?

Etc...



EDIT: I moved this post and the one it is a reply to out of someone else's build thread (please don't post troubleshooting questions in other people's build threads, especially since you already have a thread going people are helping you in). So the stricken-out parts of the post above no longer apply.

 

[simplydata]

Depends on your terrain, hills, winds, road conditions, tire inflation/rolling resistance, system voltage, motor kV (RPM/volt), how your controller responds to throttle, any controller limitations, what assist mode / level it is in and what those are setup as, etc.



Which version of the Grin All Axle motor are you using? (presumably that's the motor you're using as that is what this thread is for, that you are posting to)

Which specific controller are you using?

I used v3 before but v6 for the new one.

How is the controller setup? (what settings are you using?)

The setup was done by Grin for the controller.

What battery voltage are you using?

Which specific battery are you using?
-Same 48v battery I used

What are your terrain, road, wind conditions?
- I tested on a flat road, riding in both directions. no winds..
Etc...



EDIT: I moved this post and the one it is a reply to out of someone else's build thread (please don't post troubleshooting questions in other people's build threads, especially since you already have a thread going people are helping you in). So the stricken-out parts of the post above no longer apply.

I verified my setup with Grin, and they confirmed that the speed I’m getting is normal. My previous RH212 test was done with an extra 30 lbs from two solar panels and a frame. I usually set my max to 200W for most of my rides, so this new experience has been somewhat disappointing. I’m just trying to see what results others are getting.. thanks!

 

[simplydata]

Looks pretty even to me (assuming 200W battery)
View attachment 372945

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I wish I get the same number but I don't. I may have defected motor but Grin verified the speed is normal.

 

[simplydata]

Can we get a good picture of your trike?

This is my new setup. Previous trikes were Catrike Road and Catrike Dumont with 30lbs extra weight using same RH212. I was expecting faster since I have not put the panels yet.

 

[neptronix]

Hmm, the bike with the side bag is probably getting docked some aerodynamics points.

But DD motors are not known to be efficient well below their watt rating. They have an efficiency curve and you are at the worst part of it.

One difference between the two bikes is the diameter of motor and more poles on the RH212.
The RH212 is a lot more efficient at low rpm due to the difference in design.
Some combination of this and the side mounted bag is probably responsible for the differential

 

[simplydata]

Hmm, the bike with the side bag is probably getting docked some aerodynamics points.

But DD motors are not known to be efficient well below their watt rating. They have an efficiency curve and you are at the worst part of it.

One difference between the two bikes is the diameter of motor and more poles on the RH212.
The RH212 is a lot more efficient at low rpm due to the difference in design.
Some combination of this and the side mounted bag is probably responsible for the differential

Side bag and rear rack were not installed at the time. I also tested additional 40 miles with the same result. I am trying to see anyone using the motor and hoping to compare. I do like the motor for much simpler install process.

 

[neptronix]

Good info. What kind of watts do you see at higher speeds?

 

[simplydata]

Most of time, I set 200w since I get around 200w from my panels. I have not checked how fast I get for higher watts yet . My usual speed is around 18mph at 200w plus my input. The power cut off at 20 mph max. Thanks