My second e-bike: Reality Check? (Pretty please?)

[Joe Perez]

I declare my Independence... from gasoline!

(Just occurred to me that I haven't driven my car in two weeks.)

[GMUseless]

Hey Joe. Congrats on your emancipation! I just caught up with your build thread today. Glad to see you got a MAC...those bitches are so surprising for how small and compact they are. And crazily efficient as well!

How's your wH/mile holding up?

After two weeks in the saddle...cretainly the build bug has you eyeing some upgrades?

[Joe Perez]

Hey Joe. Congrats on your emancipation! I just caught up with your build thread today. Glad to see you got a MAC...those bitches are so surprising for how small and compact they are. And crazily efficient as well!

Yeah, it really was a shocker, especially moving up from the old Amped system that had been giving me so much trouble. There haven't really been any updates here because there's just not been much to report. This thing is working perfectly, and does exactly what I hoped it would.

There have been a couple of occasions where it felt like I was really straining the system, but then I've realized "hmm. I'm going up a 10° incline at nearly 25 MPH. I could probably slow down just a tad."

How's your wH/mile holding up?

After a full day's commute cycle (10-14 miles, depending on route) I'm averaging in the 17-18 wh/mi range overall. It's higher in the morning, as I'm going mostly uphill, lower in the afternoon. And of course the pedaling effort is much higher coming home from work than heading in, as I'm not as concerned with arriving home dripping with sweat. On the weekends, when I just go out for shopping for for fun, I see as little as 14-15 wh/mi (generally this is less hilly terrain as well.)

After two weeks in the saddle...cretainly the build bug has you eyeing some upgrades?

Not really.

This bike *IS* the upgrade from the last one. Totally new build from the ground up. If I lived on flat terrain, it would actually be massive overkill. As it is, this seems to be the real sweet-spot. I feel like I'm right at the upper limit of having a "motor-assisted bicycle" as opposed to a scooter. Any more power and there'd be no point in having pedals and a chain.



Also, for those who didn't get the joke in my last post, 04 July (date of post) is the anniversary of the signing of the US Deceleration of Independence from the British Empire.

[tyrion]

As a fellow San Diegan considering a Mac motor from cell_man, I really enjoyed reading this thread. Thanks Joe for documenting your thinking, decision, and build.

I'm thinking of going with the 10T and frame battery as well. Also on a Giant (although older model) hardtail mountain bike. I don't have many hills on my commute but there are certainly a bunch around San Diego and I'd like to be able to ride around without having to fear them.

A few questions (if you're still following things):

Could you update on how everything is running after a full summer of use?

What kinds of top speeds are you seeing (without pedaling)?

What size is your frame?

Anything you wish you had done differently? Different battery? Motor? Full suspension? etc...

Thanks again!

[veloman]

Yes the Mac's have great starting torque and seem to do "more" with peak watts than a DD. Great option if you are running lower battery power and have hills or lots of stops. But, my 9c is more efficient at cruising and if I am smart with the throttle I can get better wh/mile, especially with regen in the city.

The other problem I had with Macs is the inability to handle heat and going over 90 degrees Celsius at 20wh/mile in 95 F ambient temps. Even at 15wh/mile the temp would still keep rising above 90 C, and it was only 85 F!

[Joe Perez]

As a fellow San Diegan considering a Mac motor from cell_man, I really enjoyed reading this thread. Thanks Joe for documenting your thinking, decision, and build.

I'm thinking of going with the 10T and frame battery as well. Also on a Giant (although older model) hardtail mountain bike. I don't have many hills on my commute but there are certainly a bunch around San Diego and I'd like to be able to ride around without having to fear them.

A few questions (if you're still following things):

Could you update on how everything is running after a full summer of use?

It's been just absolutely fabulous. The old AmpedBikes system always felt anemic and underpowered, popped fuses at least once a week, and blew the BMS twice. The Cell_Man system, by comparison, has been 100% reliable. The CA3 firmware had a few bumps along the way during the beta phase, but it has now reached a good level of stability, and the closed-loop current mode throttle works wonderfully (eg: push the throttle to 50% of travel, and you get 50% of rated current regardless of speed or incline.)

All in all, the system is working exactly as I'd hoped.

What kinds of top speeds are you seeing (without pedaling)?

I have no idea, as I always pedal. With average effort, I can easily cruise at 25 MPH on level ground, climb moderate inclines at 20 MPH with heavy pedaling effort, and my top speed downhill so far has been 36 MPH.

What size is your frame?

It's a "Large" in Giant's terminology, whatever that translates to in the real world. I'm no bicycle expect. I am about 6'2", and this frame is probably a tad smaller than would be recommended for me, but I've always preferred smaller vehicles, be they cars, motorcycles or bikes.

Anything you wish you had done differently? Different battery? Motor? Full suspension? etc...

Not really.

The motor is just fabulous for my needs. The battery has also been great. If there were a choice to have it wired for 20S4P instead of 16S5P, I might be tempted to go for the extra voltage, but this is honestly a trivial point. Stepping up from an anemic 36v battery to this rugged 52v powerhouse was the difference between night and day.

As to full-suspension... When I first started frame shopping for this bike, I was leaning in that direction mostly because I thought it looked cool. But there are two major factors weighing against it. Battery fitment is one, and the other is that a rear suspension tends to soak up some of your pedaling effort, resulting in reduced efficiency. And having a hard-tail hasn't really been bothersome. In part, this is probably because I tend to stick to pavement and very well-maintained trails (mostly pedestrian walking paths between housing developments and office parks.) I'm not running especially fat tires, either. Given the choice between a rear suspension and having the perfect place to hide a large battery, I'll gladly give up the suspension. It's just not needed for a commuter bike.

[Joe Perez]

Yes the Mac's have great starting torque and seem to do "more" with peak watts than a DD. Great option if you are running lower battery power and have hills or lots of stops. But, my 9c is more efficient at cruising and if I am smart with the throttle I can get better wh/mile, especially with regen in the city.

No doubt that a direct-drive will be capable of higher efficiency given the right terrain. In my case, I'd already tried a 9c, and with the hills we've got out here, it just wasn't the right thing.

I also didn't really anticipate how much better the geared motor would be in terms of freewheeling when unpowered. With my last motor, I just wrote it off to having a heavy bike. But now that I have a geared motor, the bike really is much more pleasant to ride when I'm on flat terrain in pedal-only mode. It no longer feels like I'm dragging a bag of dead cats behind me with a flat tire all the time.

The other problem I had with Macs is the inability to handle heat and going over 90 degrees Celsius at 20wh/mile in 95 F ambient temps. Even at 15wh/mile the temp would still keep rising above 90 C, and it was only 85 F!

You must be pushing it a lot harder than I am.

In my daily commute, I hardly ever see 60 degrees C by the end of the ride. The highest temp I've seen was 72 degrees, and that was after a 21 mile ride on varied terrain. Obviously I was keeping an eye on motor temp and trying not to let it get too high, but I can't imagine what I'd have to do to push it to 90.

[veloman]

nope, I am at the same wh/mile as you, so not pushing it harder. Mine is an 8 turn, but its not hilly here.

What is your ambient temp?

[Joe Perez]

What is your ambient temp?

Morning are usually in the low 70s, afternoons can be anywhere from the mid 70s to high 80s.

My typical end-of-ride temp (5-6 miles of moderate terrain) is typically in the 50-55 degree C vicinity, depending on how hard I've been leaning on the system vs. pedaling.

One thing I have a hard time figuring out is just how hot is "too hot". Hall sensors of the sort we commonly use (eg: SS41, AH3503, etc) are typically rated for operation all the way to 150 degrees, and while I have no solid data, I can't imagine that the varnish on the windings would tend to fail below that point either.

[Trilska]

This might end up being a late kidnaping, but i got inspiered about mac talk, and sence i am in a simular situation i hope i could get some advice.

How does a 12t MAC in a etro 405 wheel (20'') sound?
And sence i am after around 50km/h i figure i would have to feed it around 90-100V(24s lipo).
With a total weight of around 150kg would this system have posibilitys to be relable, or will i just end up destroying somthing?

And when we talk about something getting destroyed, will it be the gears or the clutch? And how much of a factor is heat in this equvation? Sence the heat isue is the nr 1 reason that i am qonsidering the 12t and then throw voltage at it to get my desiered speed.