My new (finally!) assembled E-bike, with pictures!

Hi everybody,
After all my questions here during the recent months, I am happy to show you my built E-bike.
The bicycle is a Mongoose otero elite full suspension MTB, with 26inch wheels.
I bought it used specially for this project, because nowadays 26inch MTB's are very cheap.
It has 24gears, the rear shock absorber is SR Suntour "Epicon" which is air inflated (200PSI max), and the front is a simple elastomer SR Suntour:


There are two motors.
Front 9C+ 2706:

You can see how I used the disc-brake boss for a snug fit of the torque arm in the following close up image:


Although the bike originally came with hydraulic disc brakes, I changed the front one to V-brake for two reasons:
1. The 2706 has compatibility issues with discs
2. I couldn't find E-brake lever for hydraulic brakes...

The rear motor is the new cassette version of the 250rpm ezee, called ezee250rc on Grin website:

That modern motor fits the disc rotor perfectly as it was just a standard hub. The 8 speed cassette has been transferred as well - It's so nice to have the modern cassette-freewheel, instead of the older threads.
One downside (but also a plus-side), is that the ezee comes with a high quality cassette-freewheel, and since it has like 100 pawls it makes a much stronger buzz than the cheaper freewheels.
I used a front torque arm for the ezee, as you can see in the pic:

Why?
The V4 rear one couldn't be made to fit, since the frame has pivoting points very close to the dropout.
I mounted the torque arm, and using a hose-clamp applied a moderate forward torque which preloads it against the axle in the correct direction - The ezee only applies negative torque on the dropout since it has no regen. (yet... :wink: )

At the beginning of the project, I only had the front 2706 motor, powered by Grinfineon 72V40A. I didn't like the lack of traction, the fact the motor was overheating very quickly on the insane uphills we got here, and the throttle->speed mapping of the regular trapezoid controller made me nuts with it's lack of sensitivity. So I switched to the Phaserunner.
I bought two of them - for the front 2706 and for the rear ezee:


The Phaserunners worth every $ of the 295$ I spent on each of them. They (finally) let you do throttle->torque mapping, just like a normal motorcycle. They allow you to limit the phase-current, which solves ALL of the overheating issues, and since you limit the phase-current (and therefore the torque), and combined with the sine-wave - the gears of the ezee would live happily for many years. The ezee motor makes barely any audible noise! It's amazing.
Of course - 2 phaserunners also weight around the same weight of one Grinfineon 72V40A. Yes, the Grinfineon can take alot more abuse with it's 12FETs, but that "extra" power will mostly be converted to heat on the 2706, as I witnessed.
Two motors share perfectly the load together!
I set the 2706 to 55A phase current limit, and the ezee to 45A. No more high temps, smooth accelerations even from standstill at 13%+ grade, and addictive 2WD traction.

Now let's talk about the batteries.
During the testing, I used 4 A123 packs - each with 26650 cells at 12S1P configuration - 39.6V 2.3Ah for each.
All four were connected together to a pack either at 39.6V 9.2Ah configuration or 79.2V 4.6Ah.
Range was very short, but it taught me alot of things:
1. The Grinfineon is best if used at the 39.6V setting. The higher 79.2V was mapping a much bigger speed range with the same throttle twist, making the torque control very unpleasant and jumpy.
2. 79.2V allowed me to reach speeds on the flat of around 70Km/h (using only the 2706 while the ezee was freewheeling), while on uphills both motors worked together and achieved climbing speeds of 50-60Km/h - at 10% grades! (With the two phaserunners)
3. The Phaserunner doesn't care a shit about speed, only on torque - As long as you have enough battery voltage to overcome the back EMF. This means that the throttle control feels the same with either 39.6V or 79.2V. The only difference is that the 39.6V would limit your top speed much sooner. For more speed I could have enabled the field weakening, but I find it better to just have battery voltage which equals the highest (ever) speed I might need. (For example to merge with busy traffic). I tried the field weakening and it works just as promised - so you know in case you need it.

For the final battery pack I had a lot of dilemas: Voltage, Capacity, chemistry, and where to buy from. I was very close to buy NCA pack from em3ev, but eventually I bought a bunch of used A123 prismatic cells - 20Ah each. Since each cell is almost 500grams, I couldn't get to the high voltage I wanted - and settled on 17S - 56.1V with 20Ah capacity. That was the maximum voltage I could have charged with my 48V8A Satiator. (It goes up to 63V)
The pack weights 9Kg all together, which is only 0.5Kg over the weight of the packs themselves. Thanks to that I could stay very close to the 133Wh/Kg density of each of those cells, which is not very far from AllCells which have a much lower cycle-life and higher voltage sag.
Here are several pictures:


View attachment 6


I used the original modular plastics that connects the cells together, but since they force to have a spacing material I improvised and used only half a plastic line at a time - so I can keep the cells touching each other. (That was the biggest weight saver).
There is no BMS, yet, and I dunno if I am going to get one. I plan to just charge to 3.5V/cell. You are allowed to 3.6V/cell, but the amount of additional energy going in by 3.5->3.6 is so negligible, it just doesn't worth the risk. I programmed the Phaserunners to LVC of 2.5V/cell but they start to ramp it down at 2.7V. The upper limit for regen was programmed at 3.5V/cell.
What do you think?

You can also see in one of the pictures how I used a 40A circuit breaker both as protection and to take the initial sparks at powerup. There are two parallel wires of similar gauge coming from the battery (for each controller), and each is terminated at it's own Anderson terminal. Since I draw around a max of 50A-60A - that should be around 25A-30A for each Anderson to bear.
All 4 Andersons are modulated together - so I can connect/disconnect both controllers at once.
I wanted the battery to be quick-released for charging scenarios where I can't get the bike close to the outlet.

And here is the battery rack:


I used a seatpost rack rated at 15Kg. I will take it as 10Kg as a more realistic value, but since I am using a full suspension bike and the battery weight is sprung, I was less worried.
I fortified the rack as you can see with hose-clamp, transferring some of the load to the saddle, and an extra plastic cable tie - just for the sake of good luck.
What do you think?
While riding on bumpy roads today - I felt the suspension was doing it's job very well - as no shocks were transferred to the frame.
Using that kind of rack, allows me to use the quick release mechanism of the seat tube to take the battery with me.

And last - throttles.
I use two of them - right one for the front 2706, and left for the rear ezee.
I was thinking about fusing them into just one, controlling both motors - but it's just not realistic. There are situations I just want to use the direct drive 2706:
1. Slow cruising on flats at walking speed, or very high speeds on flats. (the ezee would be an energy waster here).
2. Regen braking - I twist the throttle for the proportional regen. The ezee doesn't need to be involved, although that can just make it stop as well. (and do nothing as it's freewheeling).
3. Stairs climbing - I dial a 250W power limit on the CA powering the front 2706, and it's just pulling the bike upstairs. No need for me to carry that weight! A direct-drive + phaserunner with it's accurate torque selection is perfect for that - The grinfineon was trying to kill the 2706 when doing the same..

Here are pictures of the throttles and the dual CA's. Each motor has it's own CA display.




To conclude - I chose one geared motor and one direct drive to enjoy both worlds. That ezee motor is so impressive with it's torque output (taking WAY less power the 2706 would have needed to output the same torque) it's just an amazing piece of technology!
The ezee is dialled with it's left throttle to do most of the work on uphills while the 2706 is supporting it (I use the potentiometer to limit it's output power on that scenario). On flat-cruising and downhills - the 2706 do solely all the work.

That is all folks. What do you think?

P.S - The build is not final - there are just cosmetic works left: I still need to make everything waterproof, cut the nylon cable ties (once they settle down and I finish tightening them), and to make the battery sealed - with or without BMS.

I just thought I would point out a couple of things;
The way to activate the E brake function when using hydro brakes is to install a small reed switch @ one of the handlebar levers. There are several ways to rig it, but I think the best solution that is documented here was by D8veh. Searching his posts using the search-words Ebrake switch should bring it up.
I tried the opposite throttles approach when I first converted to 2WD years ago and found it awkward. The best set-up for me involves two throttles side-by-side, A left-hand half-twist next to a thumb;




It's very intuitive to use.
Lastly, I guess I was lucky w/ the V4 TA on an Ezee'



But, of course every chain stay is different.
I would suggest a second torque arm on the other side.

I recall you mentioned using this bike off-road, is that still your intent?
If so, I see a few things that throw some "red flags", but there is no point in me sounding overly critical if you are going to stay on the pavement.

motomech said:

I just thought I would point out a couple of things;
The way to activate the E brake function when using hydro brakes is to install a small reed switch @ one of the handlebar levers. There are several ways to rig it, but I think the best solution that is documented here was by D8veh. Searching his posts using the search-words Ebrake switch should bring it up.
I tried the opposite throttles approach when I first converted to 2WD years ago and found it awkward. The best set-up for me involves two throttles side-by-side, A left-hand half-twist next to a thumb;


It's very intuitive to use.
Lastly, I guess I was lucky w/ the V4 TA on an Ezee'

But, of course every chain stay is different.
I would suggest a second torque arm on the other side.

I recall you mentioned using this bike off-road, is that still your intent?
If so, I see a few things that throw some "red flags", but there is no point in me sounding overly critical if you are going to stay on the pavement.

Click to expand...

Hi, I thought about an external micro-switch, but I find the E-brake lever a comfortable turn-key product. In case I will upgrade to disc brake (if I change the 9C+ 2706), I will just use mechanical disc brake.
I tried the thumb-throttle for some time on my previous-previous e-bike, and I realized I will develop necrosis in my thumb if I keep doing that. Maybe it's just a personal preference.
I find the dual left+right twist throttle very comfortable - since I don't use both motors all the time as I wrote, so it's good to have the control. If I had two identical motors, then of course I would unify them into one throttle.

Regarding twist throttles, let me ask: I find my hands (and my back) getting quite exhausted after twisting for such a long time. I know I can use the CA's cruise control, but it's not practical for city driving.
My previous E-bike was a pedalec one, and I always used ergonomic handle-bars to grip my hands on. (not possible with throttles where you have to grip them in a certain way).
So maybe it's because I am not used to that mode of operation? (I also never rode a motorcycle in my life)

And yes, you were lucky with the V4 TA. It's just frame dependant. I think my front-TA do quite a good job there.
I agree a second torque arm can be important for a torquey motor like the ezee, but for that I will have to cut&reclamp the phase connectors and the jst ones. I find that too much of a hassle. There is no way to install without removing them, right?

Yes, I plan to go on very gentle off roads - not as purpose of the ride - only when necessary to reach a farm/location/gravelled parking lot/etc.
Although I do wonder if that full suspension MTB can go on off roads that any family car can visit - at moderate speeds like 20km/h or so. What is your opinion about this?

eTrike said:

That's a fantastic machine you've assembled! First build you say?!?
You went with 2WD geared/DD for best of both worlds, best battery choice (which you got for next to free btw!), dual phaserunners... Herly freck that is a nice setup... I honestly think this setup is one of the best I've seen all around. Definitely wins the award for best first ebike build if so!

it is clear from your writing that you really did you homework. Kudos again!

Color me jealous, and I don't even like bikes

Click to expand...

Thank you
It's not my first build - I have built several ebikes before, back to the days of SLA with relays as controllers. This one, however, is the first one which I totally see as a possible polluting car replacement. It can propel you at any grade and sustain speeds of 50km/h while climbing.
I bought many extra 20Ah cells which I plan to assemble for different battery needs: Car jumpstart, UPS extended backup, and an extra battery for this E-bike which I can mount for very long journeys.
I now wonder maybe there is a better way to place the battery around the bike? I will consider only sprung areas, as the battery's weight is significant. (9Kg with 1122Wh)

You cost me money !
This was the first I heard of the Phaserunner (how could I have missed it) ... so after seeing your post I looked it up and read the various threads. Now I have one on order along with a CA for my Weight Wennie bike. With only a single 36V 250 watt motor it is not nearly the beasty you have but with a motor that small, it needs all the advantages it can get. Also for my purpose I like the idea of fewer wires/cables.

With regards to your battery: have you thought of losing the water bottle and building sort of a upside down "U" shaped pack around the down tube. That is 'sprung' and it would lower the center of gravity as well ... just a thought.

LewTwo said:

You cost me money !
This was the first I heard of the Phaserunner (how could I have missed it) ... so after seeing your post I looked it up and read the various threads. Now I have one on order along with a CA for my Weight Wennie bike. With only a single 36V 250 watt motor it is not nearly the beasty you have but with a motor that small, it needs all the advantages it can get. Also for my purpose I like the idea of fewer wires/cables.

With regards to your battery: have you thought of losing the water bottle and building sort of a upside down "U" shaped pack around the down tube. That is 'sprung' and it would lower the center of gravity as well ... just a thought.

Click to expand...

For small (geared?) 250W motor, the phaserunner can literally mean much longer life for the motor, so you will discover that I actually SAVED you money over time! :wink:
Research very well what is your recommended max phase current limit and set that. No need for any battery current limit in motor's perspective - only following your battery's current draw limit.
You can use Grin simulator to find the point where the phase current is starting to cause overheat over 30min or so - this is your first good guess for it's value.
Second and better guess - would be to check what phase current is being drawn by the motor at it's rated 250W power output condition at moderate uphills.
For the ezee - that value was being set to 45A.

Oh, I forgat to reply about your "U" shaped battery packaging:
Those cells are quite big. Did you see them in reality?
I was quite surprised when I saw how much bigger they were than what I have imagined.
Look how much volume 17 of these take on the seat post rack.
I was considering the "U" option - and it would be too low and too close to the ground. Sideways you don't have much option either as just a few of these each side and you have reached the safe limit you should keep from the spinning pedals and your shows.
But thanks for the idea!
Maybe you have other ideas?
Are there any turn-key products for sprung front-racks AND rear-racks for full suspension MTB's ?

Look out for some of these forks. They're steel, so much better for a high power front motor:

http://www.ebay.co.uk/itm/mountain-bike-forks-make-zoom-gordo-/351864560079?hash=item51ecc319cf:g~EAAOSwNRdX89kb

d8veh said:

Look out for some of these forks. They're steel, so much better for a high power front motor:

http://www.ebay.co.uk/itm/mountain-bike-forks-make-zoom-gordo-/351864560079?hash=item51ecc319cf:g~EAAOSwNRdX89kb

Click to expand...

Thanks for the recommendation, but buying and sending such items overseas is a killer shipping for where I live.
Also I think I do not need to be worried about fork strength, since I divide the torque load between two motors. Especially since I also limit the phase-currents of the motors with the phaserunners, while regular trap-controller would allow twice or even more with it's (almost) unregulated phase currents - especially at takeoff.