Help on building a first commuter ebike.

[william]

Hello Endless Sphere!

This is my first post on this forum and I would like to ask for your help on choosing a suitable kit for a commuter bike. This would be my first ebike and after reading everything I found from the forum I still have some questions. Let me quickly describe my needs:

The route:
My goal is to commute 30km daily (15km one way) mostly on a dirt road with one larger hill (max 7% grade for about 40m elevation). I live in Finland so conditions vary from sunny summer days to lots of rain during autumn and freezing and snow in the winter. The dirt road part has a lot of holes and bumps.

Performance:
Street legal means 250W, 25km/h max assist speed and assist only when pedaling. The power limit will be 1000W next year so that's my power goal. I'd like get 35-40km/h on a flat with minimal pedaling since there won't be anyone to bother on the dirt road.

The bike:
I would build my first ride on my aluminium Marin hardtail. The dirt road would really be nice on full suspension but then the battery placement becomes difficult as discussed on many threads on the forum.

The Kit:
I would like to buy a single all in one kit. I'd like to get riding rather than fiddling with components. I am a science teacher with physics as my major so i guess i'll end up disassembling and tuning my gear eventually, but now i'd like to start with an easy kit.

My current choice would be a rear wheel MAC from em3ev.com with their 24.8Ah (~1250Whr) frame battery, a 40A controller with Cycle analyst V3. With CA V3 I could manage the legal limits easily and It would have plenty of power reserve for those difficult weathers.

And now for the questions:

Geared motor wear?
How big will the wear be on the geared motor? Will I run through many gearsets and clutches a year with 6000km of riding?
I like the smaller size and freewheeling with the geared motor and there isn't really any regen to speak of with the minimal hills. So basically a DD is better only in durability (and maybe efficiency?).
If I would still be better off with a direct drive, is there a comparable kit option somwhere?

Noise?
I have tested a crystalyte front DD motor and have a sense of the noise level. How much noisier is the MAC?

Mac motor weather sealing?
I read that the MAC is not really weather sealed so will it stand up to riding in the rain regularly?

Is the battery overkill?
I really like the 1250Whr capacity so I won't need to charge at work and will have capacity to spare even when the pack ages. Would there still be some benefit from choosing the smaller 16,5Ah option?

Battery in freezing temperatures?
I would not be able to store my bike in a warm place at work so it will freeze during the workday. Is the battery easily removable from the frame bag so I can take in inside?

Other good kit options?
I haven't yet found anything that would look as good as em3ev.com kits, but please let me know if there are any.

What have I missed?
I'm sure there's lots, but what major features would I still need to consider when building a commuter ebike?

So if you can shed some light on my questions i'd greatly appreciate it!

 

[dogman dan]

You ask all the right questions.

For max durablility, a direct drive would be best. But I see no reason a Mac couldn't handle that ride.

A mac will be noisier than a DD for sure, but not to the point it becomes torture. People will turn and look, "whats that?" when you go by on a gear motor.

I can't say about gear wear, but I can say that for a truly reliable commute, eventually having two of many items is a good thing, two motors, two throttles, two controllers. No reason not to have these items on a second bike. The spare controller can be cheaper and less powerful. Get a cheap china ebay kit later as your spare?

40 kph will be there with a 10t Mac on 48v, or a 9 continent in 9x7 winding.

40 amps, at 48v, is 2000 watts. I'd say you really only need 25-30 amps controller. But if you get the CA, you can always dial in the power you want.

Battery can't be overkilled, except for being too big to carry, or too big for your wallet. I suspect the dirt part of the ride will use more power than normal street commutes, so a 1000wh pack might be a good choice. Slowing down, you'd still make it on 800wh. Charging at work would be ideal, allowing a much lighter battery to be carried.

 

[dancliff]

I bought a MAC 10T kit w/ 30A controller and a 14s, 14Ahr battery from EM3EV back in July, and I have about 1500km on it now with a commute distance and gradient profile similar to yours. The main difference would be that my commute doesn't include dirt roads.

Regarding your questions:

Geared Motor Wear
I don't know yet, but I've read that the clutch is more likely to fail than the gears. I use a three speed switch, starting from a stop in the lowest setting and I pedal to get going. I've also modified the controller settings to reduce the ratio of phase current to battery current in order to make the throttle smoother off the line.

Noise?
It's noticeable, but I haven't really noticed people turning to look. If you look up build threads for MAC commuters where they post videos (Search on users Cresh and Supertux1 for instance), it sounds kind of loud, but it seems to be less noticeable in person.

MAC Motor Sealing
As long as you don't submerge the hub and you pay attention to having a drip loop for the motor cable, it will probably be fine. I've been caught out in heavy downpours 4-5 times this summer, and so far no issues. I understand that keeping water out of the controller is more important.

Battery Overkill
I have a 14s, 14Ahr battery and use somewhere between 300-350 Whr for my round-trip commute of 32km, and I don't recharge at work. I also have plenty of capacity left over to run to the store or go to the gym in the evening. I probably cruise at 30-32 km/hr and I add light to moderate pedaling, so your consumption will be higher if you travel at 40 km/hr and/or don't pedal.

Battery in freezing temperature
The battery and connection to the controller are top-notch on this kit. It's wired with a pre-charge tail using Anderson power-pole connectors, so you can easily connect/disconnect the battery and remove it from the frame bag.

Regards,

Dancliff

 

[Drunkskunk]

The t5hing that will kill a MAC motor the fastest is overpowering them. With the wetup the way you listed it, the controller can feed it 2000 watts, which is about 500 more than it should get. Get the CA and turn down the amperage so it only pulls 1500w max and you shouldn't need to worry about the clutches or gears.

Your battery is overkill 3 seasons of the year, however, lithium loose capacity when it's very cold. how much depends on how cold. So for winter you'll need a big battery if you can't keep it warm.

Weather proof is more about how you set up the bike. make sure all your cables are routed with driploops, and that the connectors are never in a low spot along the cable run, and it should be fine.

As for a hard tail off road, that should be fine. go with the biggest tires you can fir, especially on the rear. you might even consider going down one rim size to fit a bigger tire in the frame.

 

[william]

Thank you for the great replies!

For max durablility, a direct drive would be best. But I see no reason a Mac couldn't handle that ride.

A mac will be noisier than a DD for sure, but not to the point it becomes torture. People will turn and look, "whats that?" when you go by on a gear motor.

I can't say about gear wear, but I can say that for a truly reliable commute, eventually having two of many items is a good thing, two motors, two throttles, two controllers. No reason not to have these items on a second bike. The spare controller can be cheaper and less powerful. Get a cheap china ebay kit later as your spare?

For a commuter I might easily gravitate towards a DD for the reliability. The thing is I haven't really found a good kit with a nice battery and a CA V3. Ordering a crystalyte kit from ebikes.ca is not affordable because of shipping. What good options would I have for a DD kit?

As for your second point about two systems I'm eventually going to build a second ebike for my wife. I'm actually thinking I might just start off with this MAC kit to learn how these things work and later build something around a DD hub as a more serious commuter. We would then have two systems and the geared motor would be great for my wife pulling two kids in a trailer. Would there be any downsides to this approach?

I guess I could just build something from parts now. I just feel I don't yet know enough about controllers and their inner workings to be able to know what controller works with what hub and CA and battery and work out their connectors.

40 amps, at 48v, is 2000 watts. I'd say you really only need 25-30 amps controller. But if you get the CA, you can always dial in the power you want.

I know 40A is too much with a MAC at 48V. I just thought why not get a beefy controller and limit it with CA. I would then have a powerful controller when I build something new or repurpose it elsewhere later. Is there a downside to running an unnecessarily large controller with a CA limit?

I bought a MAC 10T kit w/ 30A controller and a 14s, 14Ahr battery from EM3EV back in July, and I have about 1500km on it now with a commute distance and gradient profile similar to yours. The main difference would be that my commute doesn't include dirt roads.
--
Battery Overkill
I have a 14s, 14Ahr battery and use somewhere between 300-350 Whr for my round-trip commute of 32km, and I don't recharge at work. I also have plenty of capacity left over to run to the store or go to the gym in the evening. I probably cruise at 30-32 km/hr and I add light to moderate pedaling, so your consumption will be higher if you travel at 40 km/hr and/or don't pedal.

This is really nice info. I doubt I would do much more than 30km/h regularly, so I would probably be fine with the 50V 16,5Ah (~825Whr) pack. On the other hand, the bigger pack costs only around 200€ more and adds only 2.3kg weight. I can avoid buying a second car with this bike so that money wouldn't cover even half the yearly insurance. And also: "Cycle life is extended (possibly doubled) by charging to 90% and limiting discharge to 90%, so you use 80% of the available capacity."(em3ev.com) I think I'll still go for the big pack just to have plenty of capacity.

The t5hing that will kill a MAC motor the fastest is overpowering them. With the wetup the way you listed it, the controller can feed it 2000 watts, which is about 500 more than it should get. Get the CA and turn down the amperage so it only pulls 1500w max and you shouldn't need to worry about the clutches or gears.

Nice to know. I would definitely limit the power with CA to around 1000W and use throttle ramping too so this should be okay.

Weather proof is more about how you set up the bike. make sure all your cables are routed with driploops, and that the connectors are never in a low spot along the cable run, and it should be fine.

As for a hard tail off road, that should be fine. go with the biggest tires you can fir, especially on the rear. you might even consider going down one rim size to fit a bigger tire in the frame.

Great! I'll make sure I get the cabeling right, would not have thought of driploops. I would assume the hardtail works well too. A nice big tire sure helps.

 

[Raged]

The other guys here know more than me, so I would take their advice in front of mine... That said.... I run a MAC10T on a 29er (700c wheel) at 40A all day every day to go to work and trail... I keep the controller in a waterproof saddle bag and ride in the rain without issues. I do park it in the garage at night though. The only issues I've had are cables getting loose and falling out. Usually the yellow cable to the motor (might replace the plugs with better bullets).

I don't have a CA so just run max power all the time as I've hardwired my 3 stage switch (really tricky on trail but fine for commute on paved road). Generally for battery life, every 5000mAH of battery will get you 15km for my setup (MAC10T, 29er wheels, 90kg rider, 12FET 40A controller and 13kg MTB). Obviously a smaller controller will get you more distance as well as peddling, The smaller battery pack is fine.


Here's a vid of it climbing a 12% hill at the local trail... its bumpy as hell, so you really don't want to go that much faster....

[youtube]pn9OPYqDvtA[/youtube]

Here is the elevation map : https://www.google.com.au/maps/dir/-37.9584916,145.2961214/-37.9581335,145.2913569/@-37.9581949,145.2937528,18z/data=!3m1!4b1!4m4!4m3!1m0!1m0!3e1

So it's about 400m travelled in a bit over a minute up a 12% incline over rough terrain.


On this video... didn't see the log until too late (first time on this single track) and hit it a bit too fast. Bounced everywhere and the connector for the yellow wire to motor popped open. Did a small service on the side of the road (found the plug and plugged it back in) and she was back up and running again.

[youtube]SkE1-D3Dhhk[/youtube]

 

[dogman dan]

Truly, a 40 amps controller does not mean you always pull 40 amps. at 48v, full speed on the flat won't pull more than 15 amps or so.

Mostly we are just recommending less amps for commute reliability. 25-30 amps should be fine with 48v.

Nothing wrong with the mac plan at all. And nothing wrong with having 40 amps at times, easy to set your own limits if you buy the DP CA.

 

[fourbanger]

Just a thought, but seeing as you're in Finland and Li-Ion temperature degradation *might* be an issue, why no put the battery pack in your backpack? If for no other reason than having a self heating (kind of) lumbar support?

 

[dogman dan]

Perhaps it could be an option for you to buy just a good controller and CA from Grin. Then with some help from us, figure out the wire color order to put that controller on a motor you get elsewhere?

If you are buying a Mac from Em3ev, then his controllers have the CA plug.