Maximum range: Drive line selection

[Low-and-Slow]

Eliminating the variables as much as I can. If you were building a recumbent trike and looking for max range, what would your choice be for a drive line. 15mph speed limit, flat ground and minimal input from pedals. I realize there are more variable that come into play, just looking for a starting point and opinions on what will work best.

 

[lnanek]

Probably a mid drive. Tough to beat the advantage of changing gears for being efficient most often.

 

[gromike]

Tadpole or delta?
And just because you didn't mention a cost limit, well, I would fit it with a couple of Grin all-axle hub motors, and fit as much battery as the bike would allow. I just bought a 36v 500w gearless hub motor for supercapacitor experimentation. It weighs 5.5 kg.!
The Grin motor weighs 4 kg. and can draw 1250w continuously.

 

[Low-and-Slow]

Tadpole or delta?
And just because you didn't mention a cost limit, well, I would fit it with a couple of Grin all-axle hub motors, and fit as much battery as the bike would allow. I just bought a 36v 500w gearless hub motor for supercapacitor experimentation. It weighs 5.5 kg.!
The Grin motor weighs 4 kg. and can draw 1250w continuously.

Tadpole, the only reason this one is not getting Grin all axle is I'm after range, not power lol. The trike it will replace is running a modded Bafang BBSHD with 80Ah of 52v batteries. Cost isn't one of the concerns within reason.

 

[offGridDownUnder]

Have you used the Grin motor simulator? I would consider it a way to play with the suggestions you get to look for surprises and find boundaries:
2 motor comparison

 

[gromike]

I don't know, but if you're doing a mid-drive conversion the Bafang is hard to beat.
I just have this thing for regen, and the robustness that comes with a DD wheel.
All roads lead to Grin in that world.

 

[neptronix]

Flat ground? try a shengyi SX2, it's 87% efficient.. if you have a driven wheel smaller than 26", it'll be torquey too.

 

[Low-and-Slow]

Have you used the Grin motor simulator? I would consider it a way to play with the suggestions you get to look for surprises and find boundaries:
2 motor comparison

I'm going to try it, but when it comes to techy programs, I have boomeritus. I muddle thru, but at this point am looking for general suggestions. I have 2 Bafang mid drives I run now, a TSDZ2B that was just put together and 2 Cyc x1 pro gen2 parts collections. What I am actually thinking about is something along the line of the old ecospeed set up to go on a Catrike frame. Low speed and long range for the rail trails.

 

[Low-and-Slow]

Flat ground? try a shengyi SX2, it's 87% efficient.. if you have a driven wheel smaller than 26", it'll be torquey too.

Looks like 16 inch front and 20 inch rear at this point on a Catrike 700 frame.

 

[neptronix]

Oh, 20" wheels gives you so much torque advantage. That's the right size wheel to put any motor in.

Motor Simulator - Tools

Here's the Shengyi SX2 in your scenario. Will climb a 10% grade and have a lot of torque. That's a 6lbs motor.

If you don't have big hills, you could get away with half the motor. I think the smallest they make geared motors is approximately 4lbs ( 250w rated, dual reductions ).

 

[Chalo]

The main thing that will get you lots of range is running the motor in its efficiency sweet spot, about 80% of its unloaded speed. Use as little battery to controller current as you can to reliably get that much cruising speed.

At your implied power level, heating won't be a factor at all. I recommend a 15A controller and whatever motor/voltage combination yields 300-320 RPM with no load on the wheel. Good motor efficiency helps a few percent, but the main thing is closely matching your cruising speed to the peak motor efficiency.

Then it's only a matter of carrying as big and energy-dense a battery as you can stand.

 

[Low-and-Slow]

I don't know, but if you're doing a mid-drive conversion the Bafang is hard to beat.
I just have this thing for regen, and the robustness that comes with a DD wheel.
All roads lead to Grin in that world.

After this project, the next will ba a hub or 2 from Justin. I really want to try an front wheel drive with 2 of the all position motors on a Catrike frame set.

 

[Low-and-Slow]

The main thing that will get you lots of range is running the motor in its efficiency sweet spot, about 80% of its unloaded speed. Use as little battery to controller current as you can to reliably get that much cruising speed.

At your implied power level, heating won't be a factor at all. I recommend a 15A controller and whatever motor/voltage combination yields 300-320 RPM with no load on the wheel. Good motor efficiency helps a few percent, but the main thing is closely matching your cruising speed to the peak motor efficiency.

Then it's only a matter of carrying as big and energy-dense a battery as you can stand.

Thanks Chalo. that's why I hang out here lol. I used a TSDZ2B since I hadn't tried one before with torque sensing. Not sure it was the right choice but range is vastly better than the BBSHD so far. It is also a lot more work lol.

 

[Low-and-Slow]

Oh, 20" wheels gives you so much torque advantage. That's the right size wheel to put any motor in.

Motor Simulator - Tools

Here's the Shengyi SX2 in your scenario. Will climb a 10% grade and have a lot of torque. That's a 6lbs motor.

If you don't have big hills, you could get away with half the motor. I think the smallest they make geared motors is approximately 4lbs ( 250w rated, dual reductions ).

No hills for this trike at all. It is only for rail to trail with a max trail speed of 15 mph. Running the TSDZ2B until I make a decision on the final motor setup.