Direct Drive Motors-Internal or External Controllers?

Hello all,

I'm returning from a long absence to the ebike scene. Between international moves I never did get around to putting together that first ebike for myself. This is what I'm about to do now and I'm trying to get up to speed again on all the ins and outs.....there's a lot of them to be aware of before purchasing.

Currently I am considering only direct drive hub motors because of their almost zero maintenance, longevity, and durability and dependability over geared motors. I'm also looking at mid drives but that is another thread for the future.

What are the advantages/disadvantages of motors with the controllers built into the hub motor vs motors with external controllers? Is this a non issue that boils down to personal preference or are there perks and benefits to one or the other? tnx

Some threads about internal controllers with useful info
https://endless-sphere.com/forums/search.php?keywords=internal*+controller*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
There's others not listed there, and not all the threads in the list itself are relevant, but it's easy to tell which are.


Also some threads about middrives vs hubmotors, with the same caveats
https://endless-sphere.com/forums/search.php?keywords=mid*+hub*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

As far as geared rear hub vs. direct drive hub longevity, I wouldn't get too hung up here, unless you can see yourself running this bike some enormous number of miles. MOST users are NOT going to wear out a set of gears in a geared hub.

Myself, after riding the same bike equipped with both a 1500w direct drive, and a MAC 12t geared hub, I found that not only was the MAC geared hub much more efficient (easy 25 mile range vs. an easy 35 mile range!), it was WAY peppier, and there was very little difference in the noise levels (one vs. the other). This in stop and go, coastal rolling hills, and speeds generally under 15mph.

My point is, even if I were to wear out a set of gears on occasion, that would be a cheap price I'd be more than willing to pay, for the extra performance from the geared hub.

For an internal controller, you would be talking about a direct drive hubmotor, which has some un-used space in it's center. If you are happy with the power of a stock unit, this might work OK because when hot-rodding, heat is the issue. Putting the controller inside a motor pairs two heat-producers into the same housing.

DD hubmotors are fine for relatively flat land in their current form. They work best with a larger diameter on the motor, and a smaller diameter on the tire. It's possible to make a DD hub with the controller inside that works great, but I haven't seen one yet that works "great". Actually, I take that back. The Stromer is pretty great, but it's also very expensive.

https://www.electricbike.com/five-hubmotors-with-the-controller-built-inside/

Controllers are making heat, motors are making heat, we don’t want them in the same casing. The controller must be in full air flow, unless you feed it lame power. If you will be feeding it lame power, then internal controller has the only turn-off to be PITA to reach and fix. And, if you will be feeding it lame power, a geared hub has no major turn-off.

If you are after performance, I have to disagree with AHicks: In terms of performance, geared motors are toys and shouldn't even be considered. A small fraction of the power that I feed to DD hubs day after day for years of hard riding, is frying a Mac instantly.

Then, some DD hubs are toys as well. Anything under 15 lbs can’t take serious power, and under 25 lbs they don’t survive very long when fed repeated high power surges in hard acceleration.

For life expectation and low maintenance, nothing beats a big DD hub 25+ lbs. I have some that are still going strong after 35000 miles, with only one bearing change around 20000 miles of beating.

Thanks fellas, external controller - DD motor it is.

Internal vs external depends a bit on the hub. All internals tend to reach scaleback temps a little earlier, some more than others.

Golden motors Magic Pie and Magic Pie Edge have included a clever forced air cooling and have done a pretty good job with isolating heat transfer conductive and convective from the stator and the controller.

In either case if its going on a trike and your average speeds are in the 10-12 MPH range (26" tire) you'll want as many stator poles as possible; a larger diameter hub. At lower speeds the switching frequency has a profound impact on efficiency which only adds to the heating. With a 20" tire 10-12 MPH enables a Direct Drive to run a higher switching frequency and work pretty well there.

We ride a pair of HPV FS26's with MAC 10T Geared hubmotors, and have 5000 miles on them, trouble free. I'll be opening the motor on one soon to inspect & Lube.

I ride EPLUS edrive equipped bike with controller built into DD hub.
it is rated 1000W and at top speed of 52km/h it draws 1500W .
of course it as USA design and build it has all kind of protections built in , overtemp the most important one,
on hot days EPLUS limits power
notice:
it does not cut off, just limit.
you have to run wires for temperature sensor inside motor , right?
inside controller cut on number of wires entering motor for sure.

miro13car said:

you have to run wires for temperature sensor inside motor , right?
inside controller cut on number of wires entering motor for sure.

Click to expand...

I wondered about that. This isn't my controller in the picture, but it's somewhat like :


A controller in the hub wouldn't need the thick yellow/green/blue wires, but it would need everything else - battery power, half a dozen controls like throttle and brake, the computer, etc. Seems like quite a bundle of wires to go in the hub.

Right off hand I don't know for sure if there's any temperature sensor support on board, but if there is it hasn't been hooked up to an external wire.

If you want acceleration then get a geared hub like the MAC...as long as you are limited on the amperage your battery can supply it will out accelerate any DD available. By limited I am talking about roughly 50A battery current which is what most of the better 14s Li Ion batteries are limited to due to their BMS (not the cells).

If you want to match the acceleration of a MAC with a DD motor, you are going to need a huge LI Ion battery or LiPos AND a controller capable of more amperage. The MAC can not compete above about 30 mph but 0-20 mph it will out accelerate the DD motor on an equivalent battery/controller. The MAC has a 5:1 gearing advantage...that is the biggest reason it accelerates quickly.

A DD motor will last longer and you can push it harder for longer periods of time as well as go faster without over heating it...just one moving part.

My advice...
A. If you are going to ride off road go with a mid drive like the BBSHD...you can gear it for constant stopping, starting, and hill climbing plus the weight distribution will help with the handling.
B. If you want to ride on pavement or relatively smooth surfaces at speeds up to approximately 30 mph go with a MAC...more acceleration and less battery required.
C. If you want to ride over 30 mph go with a DD hub motor. A geared hub will over heat.

I agree...the longevity of a MAC is not an issue. My 12T MAC is almost 10 years old and never had a problem but the DD is even better.

Don't believe me on the acceleration...check out this run using the Grin Tech Motor Simulator, it has the Cromo vs a 10T MAC but the Cromo has twice the amperage (both battery and phase) supplied:

https://ebikes.ca/tools/simulator.html?motor=GMAC10T&batt=B5216_GA&cont=cust_50_140_0.03_V&wheel=29i&mass=120&hp=0&axis=mph&cont_b=cust_100_280_0.03_V&motor_b=MCRO5004&batt_b=B5216_GA&wheel_b=29i&mass_b=120&hp_b=0&bopen=true&blue=Lbs

This run is with equal amperage and you can see the MAC accelerates quicker up to about 18.7 mph:

https://ebikes.ca/tools/simulator.html?motor=GMAC10T&batt=B5216_GA&cont=cust_50_140_0.03_V&wheel=29i&mass=120&hp=0&axis=mph&cont_b=cust_50_140_0.03_V&motor_b=MCRO5004&batt_b=B5216_GA&wheel_b=29i&mass_b=120&hp_b=0&bopen=true&blue=Lbs

You just need to pick the right system for how you are going to use it. There is no right or wrong answer, just the system that works best for your application .