2WD Radwagon upgrade questions

[RyanC]

Hey All-

New here and recently got into ebikes with a Radwagon, and have been pretty happy with it and enjoying riding/commuting by bike a lot. The main thing I would like to change is to get a longer range, but I also would really like more acceleration and climbing speed. After reading up a little and poking around the for sale section here I'm thinking that I might be able to buy a slightly used battery and geared front hub motor and possibly kill two birds with one stone for close to the same price.

So the idea would be to end up with the stock system generally in PAS1 mode only, and then use the front geared motor only with a throttle and it would have it's own controller and battery. My wife has a throttle only Hebb 500 with a 36v Ezee, it seems like if I added that to what I have it would be great.

Here are the main questions I have-

-I understand (from em3ev) I can use the stock tektro brake levers to both controllers but I have to wire both of the controllers negative to the batteries together. I'm no EE, but I can probably figure that out, just a jumper cable going from one negative lead to another (large enough cable not to get hot)? Anything to look out for here? Or any easier way to do it (2nd set of brake sensors?).

-What motors do people think would work best here? Would I benefit much from the higher torque options like a 10 or 12T mac? Or would even the faster q128 probably be a good boost (is there a front disc option)? I'm not doing any crazy steep climbs, some short %5-8 and some 2mile %2-3, acceleration up to 25mph would be nice though.

-Is this a decent plan? I also am debating a larger ~15Ah battery for the stock Shengryi and using the stock battery for the front motor...Any thoughts or experience would be appreciated. Thanks!

 

[motomech]

First off, you can drool over teklektik's 2WD Electric Yuba Mundo Build:
https://endless-sphere.com/forums/viewtopic.php?f=6&t=36959&p=536873&hilit=dual+bmc+motors#p536873
Truly a work of art, but there are simpler ways.

After reading up a little and poking around the for sale section here I'm thinking that I might be able to buy a slightly used battery and geared front hub motor and possibly kill two birds with one stone for close to the same price.

I think a larger geared motor(Mac, BMC, Ezee, BPM)is what you want, but I would be careful about buying a used battery. It most likely is a Li-Ion and that Chem. does not sit well. Ask to see the bill of sale(Date)and the bike it was installed on to judge it's history.

...any easier way to do it (2nd set of brake sensors?)

I would just make the frt. system throttle only in which case an Ebrake is not needed.

-What motors do people think would work best here? Would I benefit much from the higher torque options like a 10 or 12T mac? Or would even the faster q128 probably be a good boost (is there a front disc option)? I'm not doing any crazy steep climbs, some short %5-8 and some 2mile %2-3, acceleration up to 25mph would be nice though.

I would be nice to know the speed rating of your rear motor. With a top speed of only 20 mph on 48 Volts, one would think it's a fairly low speed, maybe a 230 rpm @ 36 Volts. Or it could be, with the rather low powered controller running it, that the top speed could be "current limited" instead of being "rpm limited".
But lets look at this from the other end. Lets say you installed a mid-speed Ezee(250 rpm @ 36 V) on the frt. and ran it on 48 Volts and a 25 to 30 Amp controller. Your top speed would be around 22 to 24 mph. I know from experience that running two exact systems in 2WD will add 2 to 3 mph to the top speed. But, assuming your rear motor will not turn as many rpms as the EZee, the two together might add 1 to 2 mph.
You don't need to consider the "torque". 2WD is all about increased hill climbing and adding an addtional motor, of just about any speed rating, will have that bike flying up hills. And there is a limit to how much power the frt. tire will put down before wanting to spin, even on a long bike. The rear motor tend to lift the frt. of the bike a bit, decreasing traction.

I also am debating a larger ~15Ah battery for the stock Shengryi and using the stock battery for the front motor.

You could, on my 2 WD, I only use the frt. motor about 25% of the time and use a much smaller battery for it.

I have tried many 2WD configurations and have ended up with the simplest possible systems. I have two completely seperate systems, 2 batteries, 2 controllers and 2 throttles.
I arrange the throttles side-by-side, w/a thumb inside of a half-twist;





It is very intuitive and easy to use.

Also, since you will not be using PAS on the frt. I would go w/ a simple controller that uses a 810 LED display. It will help to keep from cluttering up you h.bars too much, yet will provide an on/off and a 3-speed limiter. The 3-speed would be useful, you could drop down to the med. speed for a 2WD cruising top speed of 21 to 22 mph w/each motor halving the load. Then the batteries would discharge at about the same rate.
Elifebike make a nice 9-FET 20 Amp unit that can be shunt mod'ed to 25 Amps and it can sometimes be had on Ebay for $40 shipped.

The 22 or 23 mph top cruising speed may not sound like much, but it will not drop much(if at all)when encountering head winds and lesser grades.
Getting more speed would probably require adding more Volts and/or replacing both motors , mo money.

 

[RyanC]

Thanks motomech-

Yeah I read your whole thread before posting... Good stuff. I think that's somewhat the same direction I'm headed.

The radwagon motor is a direct drive, and it gets to about 25mph before it starts cutting the power. They say 20 in the promo, but you can change it in the settings.

I've seen a couple posts where it was mentioned that the torque isn't really relevant...so does this mean that EG 300rpm ezee would accelerate (or climb) just as quickly as the 250?

Any thoughts on the MXUS geared front?

Thanka

 

[motomech]

I would stay w/ a mid-speed frt. Any of those, 250 to 270 rpm @ 36 V will add a couple of mph. The 300 Ezee is a high-speed motor suited to 20" wheels. Personaly, I would go w/ a Mac 10T from Paul. Do you really need to go faster than 27 mph? Stopping distances w/ the mech. discs might start getting pretty long.
ID your motor and try matching it up on the Ebike CA sim. if you have a frt. motor that runs 3 mph or more than the rear, you will lose much of it's help @ start and low-speed Climbing.
And if you go much more than 1000watts on the frt., you wull need some fancy electronics to keep it from spinning.

Which MXUS?

 

[RyanC]

Oh no 25-27 top speed is plenty. I have a kid seat (and often a kid) on back- so it's not an aerodynamic, top-speed situation. I'm mostly concerned with average speed- which going through the city is a lot of starts and stops, some hills etc. That's why my main goals are acceleration and climbing- plus enough battery to go 30+ miles while not having to be super conservative.

The motor I have is this one-
http://www.syimotor.com/products_detail/&productId=ebaf2358-3b96-4fdd-808b-c53343210bcb.html

It's running 48v and 750w max.

The MXUS I was eyeballing was the Xf07 but now I see that it's 360rpm (that's all I can find). That part has me the most confused- it seems on here that people are saying the lower RPM motors aren't actually offering more torque- if that is the case, what is the benefit of the lower RPM models?

The MAC may be the best choice here, I was thinking there might be a slightly smaller/lighter/cheaper option that would still be good for bursts of 750w (accel) and some 2-3 minute climbs at ~500w. The BPM2 looks like pretty good there, but I don't see a 260 RPM front one.

Thanks for your time Motomech!

 

[RyanC]

I don't know where you saw 360rpm for the xf07, but I have that motor and it is nowhere near that, SFAIK it is a 260 rpm only.

In a 26" wheel it may climb decently, but top speed won't be much over 16mph or so, it does 18 mph in a 700c wheel at 36v.

Ah- thanks. Yeah I guess I saw that on a page with a bunch of motors listed. Thanks-

 

[RyanC]

ID your motor and try matching it up on the Ebike CA sim. if you have a frt. motor that runs 3 mph or more than the rear, you will lose much of it's help @ start and low-speed Climbing.

Playing with the sim. Is there a way to model the 2 motors working together? I can compare system A and B but don't see the option to compare A to A+B...Thanks-

 

[motomech]

Ok, we are really getting into some rather "involved concepts", especially the concept of "torque". Torque, when used in relation to electric motors is more complex than the simple idea of Newtonian physics "force on the end of a lever", that one associates w/ I.C. engines.
But for the sake of brevity, we with leave that for another day and someone more versed than I.
The way 2 systems are combined in regards to top speed is to move the dashed cursor line up in speed to the point where the two systems output equals the load.
Now what makes this difficult to do in your case, is we do not know the rated motor speed of your rear motor.
But we can use this deficit to illustrate an important concept when looking at hub motor performance.
Take two motors the are the same except for their speed "winds"(often a misnomer, I think), the 9C's for example.
Starting w/the 2707, we see that it's "no-load" rpm @ 36 V in 26" wheel is 285. Now note the shape of the power line(red). It "falls off a cliff" even before the "no-load speed", which tells us the motor is rpm limited.
Now plug in the 2705. We see that the power curve continues on, climbing even,
Now, it is easy to see, that if we add a second motor that has enough rpm, the 2705 will have have more available power to "sum", resulting in a combined higher top speed.
So why doesn't everyone use a high-speed motor? Well, there is a price to pay.
Note the max. efficiency numbers;
2707-83.6%
2705-80.5%
That is enough to have a noticable effect on range.
And there are a couple other "real world" considerations
How will the high-speed motor do climbing? This is a little harder to illustrate on the sim., you one can add inclines and look at the "time to overheat" numbers. But maybe a better way to look at it is to apply a "universal law" and that is; Never apply a load to a motor that is at less than half the no-load rpm. Put your incline in and look for the relative road speed. That is when it's time to get off and push. Also, since high-speed motor are starved for current, the controller tends to try and feed it everything it's worth. A rough rule of thumb is;
High-speed motors that don't reach the no-load rpm (2705) tend to overheat the controller first
and,
Low-speed motors that run @ the no-load rpm (2707), tend to overheat the motor first.
Now, what would be the best 9C for out imaginary bike that has 26' wheels?
Obviously, it would be the 2706, which gives us the best compromise of top speed and efficiency. Then, the top speed can be adjusted with Voltage while retaining the attributes we like.
Having said all this, we are really no closer to knowing the speed of your rear motor, except, it's somewhat low efficiency rating might lead us to believe it's a higher wind.
One way to test the theory is top speed runs.
If the speed continues to climb on a slight downhill, past what normally it would attain, that might indicate a higher wind.
Conversely, if it seem to have "hit the wall:, that might indicate a lower speed wind.
That' all I have time for right now.
We will try to continue discussing "which frt motor?" in the next post.
Hint; There really is nothing in the way of geared motors between the mini's and the larger ones, except the Q128, and it will not except a disc

 

[motomech]

OK, all this talk about motor speeds may not matter if you decide to go with a mini on the frt. And there are some reasons to go that route.
A mini is easy to mount and has little effect on handling and steering.
Like most hub motors, the minis come in three flavors, fairly well defined, a low-speed, a mid-speed and a high-speed.
We can eliminate the high-speed, it just wouldn't have the "torque" to add to the mix. If, for some reason you lost the rear system, I'm not sure a high-speed could pull the load to get you home.
So a mid-speed would be what you should be looking at and I would recommend what I use on the frt., the Q100H. At 2.0 Kg, it's a little lighter than most of the minis, but it is a little powerhouse. W/ it's 12:1 reduction gearing, it spins so fast that it over-performs at low speed pulling(relatively). How much will it help? You can look at the Ebike CA sim using the Outrider stand. as a sub.(Use the 9C 2707 as a sub. for your rear motor).
As you probably know, my 2WD has a Cute H up frt.(17 Amp contr). with a low powered Ezee rear(25 Amp contr.);



Using either motor only, there isn't a huge difference between the two, they are both leisurely. But the thing is, w/ 2WD the sum of the two is more than one would think. The two motors help each other stay in the most productive part of their power-bands. Accelerating together, my bike will "jump" cars at lights and barely slow down on hills, even fairly steep ones.
Now the "knock" against minis is they over-heat on sustained hard usage. But that is a non-issue with 2WD, for it would never be used all the time. How much you be inclined to use it? Well, that relates to it's one shortcoming for what you are looking for.
A Q100H, on 48 V, in a 26" wheel might hit 22-23 mph w/ no head winds. So, it's not going to add anything to the top speed(or very little). Now, since you will need a battery anyway, you could go w/ a 52 V pack, which would add 1 to 2 mph to the top speed. You could go somewhat smaller on the frt. pack, I use the frt. motor about 25% of the time, but I am happy to cruise @ 22 mph.
So that is what I would do if I were you. Q100H(260 rpm) on a 52V pack w/ a 20 Amp controller.

 

[d8veh]

When you use two separate controllers, as long as they share the same ground, you can share throttle and PAS signal wires. you only connect the throttle or PAS signal wìre to the second controller. No need for grounds because the sensor has its ground from the other controller. You must not splice in the red 5v wire because the controllers have separate 5v regulators that might not be at the same voltage, so you can get some problems.

It's the same with the brakes ii you have 3-wire switches, but if you have two-wire ones and they're the low voltage connector, you can share wires. If you use the high voltage connector you could get the same problem of different 5vs being joined between the controllers.

 

[RyanC]

Using either motor only, there isn't a huge difference between the two, they are both leisurely. But the thing is, w/ 2WD the sum of the two is more than one would think. The two motors help each other stay in the most productive part of their power-bands. Accelerating together, my bike will "jump" cars at lights and barely slow down on hills, even fairly steep ones.
Now the "knock" against minis is they over-heat on sustained hard usage. But that is a non-issue with 2WD, for it would never be used all the time. How much you be inclined to use it? Well, that relates to it's one shortcoming for what you are looking for.
A Q100H, on 48 V, in a 26" wheel might hit 22-23 mph w/ no head winds. So, it's not going to add anything to the top speed(or very little). Now, since you will need a battery anyway, you could go w/ a 52 V pack, which would add 1 to 2 mph to the top speed. You could go somewhat smaller on the frt. pack, I use the frt. motor about 25% of the time, but I am happy to cruise @ 22 mph.
So that is what I would do if I were you. Q100H(260 rpm) on a 52V pack w/ a 20 Amp controller.

Thanks yeah this is exactly what I'm hoping to get out of it and was also my thinking. Mostly what I want is to recover my speed more quickly in stop-and-go commuting, especially where it's a climb at the end of a ride (which there typically is where we live). Right now with the direct drive the acceleration get's more and more bogged down as the battery voltage runs down. The bike still can get to a nice cruising speed, but by the time I get there I'm at the next stop light/sign already.

One quick question- if you do fry a q100h, will it still freewheel? I doubt I would push it that hard, but it would be good if it did.

 

[motomech]

The Q100H should work nicely for that.
It won't "fry", but if for some reason, the system stops working, it will still free wheel.
The money you save by using the low cost Cute, can be applied to a 52 V pack :lol:

 

[RyanC]

The Q100H should work nicely for that.
It won't "fry", but if for some reason, the system stops working, it will still free wheel.
The money you save by using the low cost Cute, can be applied to a 52 V pack :lol:

Thanks man so grateful for all your help. Did you order yours from BMS? If so these would be the basic *kit* for what I need?

https://bmsbattery.com/ebike-kit/630-q100h-36v350w-front-driving-ebike-hub-motor-ebike-kit.html#/327-rpm-260
https://bmsbattery.com/ebike-parts/231-thumb-level-throttle-parts.html
https://bmsbattery.com/ebike-kit/549-s-led890-e-bike-led-meter-ebike-kit.html#/43-voltage-48v
https://bmsbattery.com/ebike-kit/788-s12sh-800w-35a-torque-simulation-sine-wave-controller-ebike-kit.html

Or a different controller?

Also looking at my frame, with some slight mods I can add a 2nd dolphin pack behind the seat tube (placed vertically going up between the rack/seat stays) and still have room for controllers behind it. This would be a good place to mount weight wise, and I like the idea of 2 dolphins, I could easily swap them to balance the load and keep the install clean.

Are the BMS batteries any good? This looks like a nice price-

https://bmsbattery.com/ebike-battery/814-36v145ah-bottle-09-panasonic-battery-charger-battery.html

And other than that I would just need the wires, maybe a torque arm or 2 and spokes and a rim?

Thanks again for helping a noob-

 

[motomech]

Yes, that's the motor.
BMS Battery's are very good, D8veh says the Panasonic cells are worth the extra money.
Correct throttle.
That controller is way too big and that display is for copying from another style display.
I use these and like them a lot;
http://www.ebay.com/itm/36V-48V-500W-9MOSFET-ebike-Electric-Bicycle-Brushless-Motor-Controller-LED-/222273910079?var=&hash=item795499dee2
Comes w/ a PAS, but you won't be using it.
You will have to change some of the connectors, I'll go over those in a little while(busy today).
But the controller to motor, you will use the female half of this;
https://bmsbattery.com/ebike-parts/439-a-pair-of-9pin-waterproof-male-female-connector-cable-for-motor-parts.html
Battery to controller-not sure at the moment-probably 12 awg silicone wire and 4 m/m bullet connectors from Hobby King. Need to see what connector are on batt., if any.Again will get into more detail later(these could be ordered after battery arrives. HK ships from U.S. West warehouse and is fast.
Wheel build-you may be able to use your existing rim, it should be 36 hole, double wall.
I just laced a Q100 to a 26" Weinmann Explorer rim and used 2.0 m/m(14 ga.?) X 242 spokes. They were a little short and I had to asemable wheel with long nipples and then replace w/ shorts to tighten . You could do this or perhaps order 244 m/m spokes.
Also get spoke wrench from BMS B. One pr. of TR's will do it unless you plan more builds.
Again, I would suggest you order BMS B. stuff and controller now and local stuff can be ordered later.
Have BMS B. confirm motor and battery spec.s in Email.
After ordering, you will not hear anything for a week or so, then they send you a tracking # and the stuff arrives in a couple of days. it's weird. At least for my motor orders. Not sure about the batt.

 

[RyanC]

I placed an order from BMSB-

I decided to go for the dolphin pack with the integrated 20a controller and panasonic cells. The integrated controller might be a bit overkill with all the extras- but for not much more $ I like that it will keep a very tidy install and save time getting it working. It looks fairly plug and play. And if it ultimately doesn't work out, or I upgrade to something else I can still use it (and the other parts) in another project down the road...

 

[motomech]

Well, I'm not sure it will save you any time, you will have to program the LCD-3
Any idea how you will mount another display?

 

[RyanC]

I hope you ordered a display, it won't work without one.

Yeah the kit that comes with the display, brake levers, PAS, battery, integrated controller and throttle-

https://bmsbattery.com/ebike-battery/680-48v116ah-bottle-09-panasonic-battery-pack-battery.html?search_query=bottle+09&results=55

2 displays is a little silly...but it's only $80 more than just the battery. I figure this will be a quicker/easier way to get started and later on I could tackle an upgrade of both controllers to a CA3 and/or torque sensing BB system etc and then use this to upgrade my wifes bike (or maybe another project!).

 

[motomech]

You could have added the SLCD-1 to your order, it is smaller and would fit/look better on the h.bars.
Or heck, once you have that you could copy the data to a 890 display.

...later on I could tackle an upgrade of both controllers to a CA3 and/or torque sensing BB system...

What's wrong w/ your current 5-speed limiting system? I.M.O., your rear drive doesn't make enough power to need/use the features of those expensive components. I would save the funds for another build.

 

[RyanC]

You could have added the SLCD-1 to your order, it is smaller and would fit/look better on the h.bars.
Or heck, once you have that you could copy the data to a 890 display.

Ah, so I can copy from the SLCD-3 to the 890? That may be worth doing at some point- On the other hand there is a lot of room on the bike to stash the SLCD-3 for now.

What's wrong w/ your current 5-speed limiting system? I.M.O., your rear drive doesn't make enough power to need/use the features of those expensive components. I would save the funds for another build.

Nothing major- the regen is a little spotty and the pedal assist is setup a little weird (all 5 modes want to take you to 25mph, just some faster than others- not great for crowded mixed use paths). I understand rad may have an updated firmware for the controller so I'm looking into that. I also just like to tinker- plus I know I'm going to need to build a better ebike for my wife at some point- which means I can use some of the stuff I'm getting now for her bike- and then use funds to upgrade mine.

 

[RyanC]

Got most of the parts in and got some work done on this- Almost ready to ride with 2wd.

I found a good condition older SID SL dual air 63mm with a long steerer. It actually makes the steering a little faster and tames some of the potholes that I can't always swing out into traffic to dodge.

One mistake (maybe) I made is I got the 36v 260RPM motor. I could swear I ordered the 200, but I did have to reload the cart and I may have selected the wrong one at that point, or maybe the mistake was not taking your advice @motomech and emailing an extra confirmation. In any case for now I can put in the LCD-3 in a top tube cell bag and watch the temp and see how it goes. I didn't even realize until after I had sanded down one edge on it, and built the wheel...

The main thing I wanted to check was to see if this install looks good/safe, I did have to clean out the dropouts a little with a file, but got a pretty snug fit. What I wasn't sure on was using 2 c washers on one side, and putting one of the torque washers between the motor and the dropout. The 2 c washers were needed so the TA fit with the air valve for the shock, and the torque arm inside was needed to prevent the motor from rubbing the inside of the fork. I didn't need much if any force to spread the dropouts, it just pops right in. The one thing I will need to do if this looks good is to dish the wheel back towards the washer side (non brake side). That might just be my newby wheel building skills as well...

I did get the 2nd dolphin battery to fit behind the seat tube and the wheel spins well...The BMS integrated controller is pretty slick, it looks like for throttle only on the front all I will need to do is short a couple leads to the controller.

One other quick question, what are the 'waterproof ebike connectors' called that are used on the Rad, Bafang, BMS kits etc? I broke one of the male ones on one of my throttles. And/or is there any place I can get a throttle (thumb or half twist) that has a male of that connector? Apparently the BBSxx kits have a female on the throttle output, where both mine are male.

Thanks again for all the help-

 

[motomech]

The "260" motor will be fine, it is much closer to the "201" than it is to the "328" and it will not "over-heat" in a 2WD application.
The motor is mounted upside down. The idea is, the cable exits downward w/ a loop to prevent water ingress. If you never ride in the wet, I guess it doesn't matter.
Don''t know about the connector.

 

[Voltron]

Re connectors... If it's the round one with the color circle at the end and the tiny tiny wires on the male, its usually sold as a Julet or a Higo.

And this was a way back ago question that you prob figured out already about why slower rpm motors, with a regular manufacturer that isn't hotrodding, for a long time it was basically 36v packs available. If you're designing it to go a legal speed, for a 700c wheel you need a lower rpm, but say for a 20" folder, you need a higher rpm motor to make the same speed. The whole torque motor/speed motor thing is marketing jive.
For aftermarket, once you settle on a voltage and a wheel size, then it's pick a kV to match your target speed.

 

[RyanC]

Re connectors... If it's the round one with the color circle at the end and the tiny tiny wires on the male, its usually sold as a Julet or a Higo.

Ah yes the Julet or Higo, bummer that these are so hard to find separately (or pigtails etc). Do you by chance know of any US sellers that have a throttle with a yellow, 3 pin male? Most pics don't show if the connector is male or female.

And this was a way back ago question that you prob figured out already about why slower rpm motors, with a regular manufacturer that isn't hotrodding, for a long time it was basically 36v packs available. If you're designing it to go a legal speed, for a 700c wheel you need a lower rpm, but say for a 20" folder, you need a higher rpm motor to make the same speed. The whole torque motor/speed motor thing is marketing jive.
For aftermarket, once you settle on a voltage and a wheel size, then it's pick a kV to match your target speed.

Yeah gotcha, when I was looking at a mac motor and emailing em3ev he also seemed to be saying that with a bigger, heavier cargo bike (and cargo) the slower RPM motors would have less risk of damaging/stripping the gears. Is that generally true (or a factor) with geared motors? Maybe I misunderstood what he was saying. Thanks

 

[RyanC]

Ok so I got everything wired up and tied down to the bike with some heavy duty cable ties for now...

The one snag I hit so far is the throttle isn't working. The LCD comes on and when I push the throttle down the LCD shows the spinning wheel icon, but it isn't actually spinning, but on the other hand holding the down mode for the 'walk' option does work. Also I put the motor on the right way (cable exits down) and also put the tire on the right way (I had it backwards), and dished the wheel back to the middle.

I did setup the P and C settings, I think P4 and C4 are the most relevant for this, but maybe I'm overlooking something. I have them set like this-

P1=201
p2=1
p3=0
p4=0
p5=0

C4=2

And I am trying to set this up with no brake sensors or PAS sensor attached so throttle only for the front motor (I can easily swap batteries front to back). I should also mention that I broke the connector for my original Radwagon throttle, but I tried the BMS thumb throttle there and it worked fine (and I like it better than the half twist- I hated the I/O switch on the one I had). Then I ordered another of the same (right thumb) except for a BBSxx, then found out that one has the female HIGO connector so I just spliced it in. They both have FT-21X on them.

Anything obvious I'm overlooking? Thanks again-

 

[docw009]

Even with no PAS sensor, you still have to select a PAS level to have the throttle work on those lCD-3's.

My C4 and P4 are 0. I tried to get throttle in PAS 0, but never succeeded.