Basic geared hub setup BUT high voltage battery, help needed.

Hello.

I have recently concluded that the hilly nature of my area (north suburbs in Athens Greece) is too much for my aging butt so I have to convert. :wink:
I am 92Kg, 1.9m and my bicycle is this:

Ideal Megisto Trekking 700c
https://www.idealbikes.net/?section=2150&language=en_US&itemid1494=2192&detail1494=1
(the same as member nomidis from Athens, hehe)

Motor:
Looking at a small, small-medium rear hub geared motor, like the Q128 (201rpm).
The main reason: NO DRAG(?) when not in use, excluding the extra weight.
If I am wrong about the 'drag' please let me know.
-Do the Q128 variants have this 'clutch' feature that disengages and frees the motor from drag when not powered?

-Does the Q128 work ok with a 6s controller? (a 12s is the proper one) or would the Q100 motor work better with the 6s?
(getting a bigger motor then the rest of the setup would make upgrades easier)

Battery:
This is where my project began, I have a couple of these unicycle batteries:
https://content.invisioncic.com/r25...ge.jpeg.7c13c737966e2e26121e29ab6dd4e10c.jpeg
and want to use one (or 2 in parallel).
This is a 2s15p battery pack charged at 61V.

So this is the tricky part,
I have seen controllers that can handle this voltage but these are high power (high cost, heavy and large) controllers that would pull max Amps from the battery.
I would like to keep the load at 10 Amps for this battery pack.
-Are there any 'small', low Amp and relative inexpensive controllers that can take the Voltage?
-Is there another solution from using this battery pack and the standard 6S, 12S controllers?

The rest will be as minimal as possible, no brakes or other sensors, no screen, only thumb throttle.
(to keep the cost, cables and complexity low)

I don't have speed or range requirements, just to be able to thumb-throttle past the hills.

I run my Q128 on a 9FET (use FET not S) controller rated for 22A max. I see no problem with your battery. A properly designed controller , if it can operate at the battery's voltage, will deliver no more current than it was designed for. You can run low power motors off large capacity batteries.

I also own some Q100H motors, powered on 20A controllers. These are our lower power bikes. I would recommend the Q128 if you're only going to have one ebike.

Like all geared motors, the Q128 has drag you can feel when you turn the axle with your fingers. When it's mounted with a rim/tire on a bike, you can spin it and it will probably only go 10-15 seconds, while a regular bike wheel will spin for a minute. I am not good enough to feel that drag when riding. Maybe a roadie can feel it. A Q128 coasts fine to me.

Hi docw009 and thank you for your reply.

This kind of motor friction seems ok to me, I just don't want to ruin my bicycle experience when not using power.

I am not familiar with controller models on the market, can you please provide a link to a such controller?

That battery will probably not work with the typical cheap "48v" controllers. As it is an unusual voltage you will have to buy a programmable controller.
I have never used a q128, but i seem to remember reading some not so good reviews on it.
If all you want to run is 20a, i would recommend the q100h. I have one on a 22a controller and it works good. If you want something bigger I would go straight to the bpm or mac.

Thank you maanebedotten.

By bpm you mean direct drive motor right?
Mac seems to be a brand?

Regarding controller, something like this?
https://www.ebike-solutions.com/en/...oller/ebs-programmable-controller-9-fet.html

The bpm is a geared hubmotor. So is the Mac. As far as I know they are the most powerful geared hubs available.
In my opinion they are the most versatile motors out there. The bike will still be pedalable, but there is enough power on tap to make it fun to ride even with minimal pedal input.

Most of my KT controllers I use are dual voltage 36V/48V which have capacitors rated for 63V, and I believe the MOSFETs will take over 100V. There would be no problem with that 55V battery, I often connect a 14S (52v) battery which is 58.6V at max charge.

Where it might get tricky is the low voltage cutoff. While my KT controllers can recognize a 10S (36V) or 13S (48V) battery, it treats the 52V as a 48V and the voltage cutoff is too low. With an LCD3 display, I can adjust the low voltage to 44V, which is almost high enough, but what I do is keep an eye on the voltage when I have 52V hooked up and not run it too low.

Q128H and Q100H made by same factory, so if one is good, both should be good. The Q128H has a lower reduction gear ratio. I use the Q100H 260rpm on 20" wheel bikes. They climb well for their small size. Must be the gearing and small wheel. Mine tends to lift the front wheel on 48V. A Q100H seems a bit small to me for a 26" or larger wheel. That's a pedaling bike with light assist.

If your hills are huge, then a BPM would make more sense to me.

A controller with LCD is good for getting speed, odometer and some will indicate your power level and voltage. Usually additional PAS levels. Also some will offer more control of power out of the controller as well as setting LVC. A controller with LED is less clutter, usually only 3 PAS levels. You buy a simple bike computer and you get more accurate speed/odometer,

I guess you are right that most 48v controllers will come with 63v caps and will probably work. Some controllers have a High voltage cutoff though, I have 2 that will not work with a fully charged 14s battery, I have to discharge down to about 56.5v before they will work. Better do some research on the exact model of controller before buying.

From what I remember reading about the q128 people didnt seem to think it could take much more power than the q100h. I dont have any links, but if you search these forum for q128 you will probably find the threads I remember reading.

The original Q128 was less than impressive from a power to weight standpoint. But it was totally redesigned several years ago and is considered to be a good performer now.
The Q128 and the BMP are completely different in form factor. The Q128 is very wide w/ a diameter not much more than a mini like the Q100, where the BMP is tall and narrow like the rest of the 5 Kg. geared motors(MAC, Ezee, etc.). The wide minis(or medis, in the case of the Q128) can sometimes be a little difficult to install as the side covers usually end up very close to the brake calipers. But I see the OP is going to use a bike w/ rim brk.s, so that should not be a concern.
My experience w/ the Q100 is, upping the Voltage does little for climbing power and even the speed increases quickly reach a "point of diminishing returns". Much above the 55 V we are talking about here, the sm. windings become saturated and there is little to be had in speed increases, but a lot more heat starts to be produced. In particular, the phase wires become prone to melting and then the windings themselves. The whole idea of taking a sm. geared motor and upping the Voltage to climb steep hills is not sound. The OP should spend some time at the Sim. @ Ebikes CA to better understand the relationship of Volts X Amps = Watts and the "time to overheat" for various grades. The best approach to climbing hills w/ sm. electric motor is to make sure the right motor speed range is selected and not to tackle long steep hills. Electric motors are not like gas engines where the rider can just "hold on the throttle and keep chugging. The electric rider needs to understand that if the climbing speed falls to less than half of the top speed, it's time to jump off and push. Otherwise, one runs the very real possibility of melting the motor.
Also the idea of being able to ride around w/ the power off is not practical for most. Yes, one can build up speed w/ the motor and then coast. But only the strongest of riders w/ the lightest possible system can pedal it around like a reg. bicycle. For the vast majority, the slight drag and, more noticable, the weight of the system, makes pedaling an ebike very tiring.

Thank you guys for the replies.

@docw009
I don't plan on climbing big or long hills and would like to keep the cost of my first kit low.

Thanks for pointing out LCD options an alternatives but in my case these are actually unwanted. (I have even uninstalled my bicycle computer)
If i can get away with just a thumb throttle then that is what I am going with.
(will have to see how that works with the controller)

@maanebedotten
The controller most likely to work ok is the one i linked above (from what I understand),
It can take the voltage and has lots of customized features on order. (like cut-off voltage)

Regarding the Q128 motors, I will try and find some more info/opinions, thanks for bringing this to my attention.
Do you know any other motors in this price range?

@motomech
It's good to hear the Q128 has improved.
I am afraid you have misunderstood my intentions, I am not using this battery to achieve better climbing or anything else, if i could i'd use a 48V battery and make things simpler for myself controller-wise but I already have a couple of these packs and the battery is half the cost of the kit.
I have a very good understanding of Li-Ion batteries and V, A and W in its principles, so no problem there, unfortunately I know very little about everything else regarding ebike kits and there is a lot of stuff. :?

I know there are limitations in using an ebike and a certain amount of respect and understanding is needed (especially on thumb-throttle systems) I will try not to abuse/overheat mine.
What I didn't know is that you have to keep that high a minimum speed (50%), thank you for letting me know.
Are you strict on that minimum? or could i get away with a third and not consider this motor/controller abuse?

I understand and agree with having a 'balanced' system.
So do you think this setup is somewhere unbalanced?
Battery:https://content.invisioncic.com/r25...ge.jpeg.7c13c737966e2e26121e29ab6dd4e10c.jpeg
Controller:https://www.ebike-solutions.com/en/...roller/ebs-programmable-controller-9-fet.html
And a Q128 motor.
Also please keep in mind that the role of this controller is to 'tame' the Voltage of the battery and not push the motor hard.
(output can be adjusted at ordering from 9A to 25A)

If it comes down to it, I have no problem whatsoever to jump off and push. (during a high or long hill)
It makes sense that the extra drag and weight will not make the bicycle experience any better but I am willing to give this hybrid system a try.
My plan B is to use 2 of these battery packs (in parallel) for a total of 640Wh of energy. That would allow me to use a lot more of that thumb-throttle.

What I didn't know is that you have to keep that high a minimum speed (50%), thank you for letting me know.
Are you strict on that minimum? or could i get away with a third and not consider this motor/controller abuse?

Click to expand...

As the climbing speed starts to fall and the motor(to use a gas eng. analogy)starts to "lug-down", the motor starts screaming for more amps, which the controller tries to provide. This is when the phase wires and eventually, the windings can start to melt. The best way to tackle hills is to hit them with all the speed you can and pedal like heck and if the hill is long and steep enough, the bike will start to slow down and you will know that in another 20 or 30 feet, it will stop. The idea is jump off before the motor comes to a stop.
How steep and long? It's hard to quantify. I would say a Q128(201) could tackle a fairly steep hill (8%), if it is only several blocks long. Conversely, w/ a 3% hill, the bike could go till the batt. drains. It's the in-between, hill between 5 and 8% that go on for miles that can be a prob. Not that common really, unless you live somewhere like Seattle.

I understand and agree with having a 'balanced' system.
So do you think this setup is somewhere unbalanced?
Battery:https://content.invisioncic.com/r254450

Click to expand...

Well, the pic doesn't tell us much. Unless my cal.s are off, that's a 6 Ah batt and paralleled, the pack would be 12 Ah. A ruff est. would be 16 to 20 miles w/ moderate pedaling.
I would be surprised if the battery pack didn't have an internal BMS, which would include a LVC (Low Voltage Cut-off), so I'm not sure that the controller has to have a LVC.
The Q128 like controllers w/ max Amp ratings in the 25A to 30A range. It sounds counter-intuitive, but higher Amps can help climbing by holding the speed better on the bottom part of the hill. that is why you don't want to "tame" the controller and reduce the Amps. Run as much power as you can and "tame" the system w/ your brain, knowing when it's time to "back-off".More than that would probably exceed the safe range of total safe power(2 to 2 1/2 times the rating, say 1600 Watts for the 800 Watt motor). Also, Amps much higher than that can make the throttle jumpy.
Your higher than 48 V batt. can help too. If your bike has 26" or bigger wheels, you might want to use the low-speed motor(201), but that motor on a bike w/ 26" wheels on 48 V pack would top out around 18 mph. A little too slow. But the 55.5V pack can bring that speed back up to 20 to 22 mph, or what the mid-speed motor(260) would do. 700cc wheels can add another couple mph. If you really won't be trying to tackle much in the way of hills, you could use the mid-speed motor, which w/ 26" wheels and 55.5 Volts would do at least 25 mph on the flat. It's tricky to select a mid-speed Q128, so if you want to go w/ it, let me know and I'll show you how.

I have a very good understanding of Li-Ion batteries and V, A and W in its principles, so no problem there, unfortunately I know very little about everything else regarding ebike kits and there is a lot of stuff. :?

Click to expand...

You should play w/ the sim.;
https://www.ebikes.ca/tools/simulator.html?bopen=false&motor=MXUS_XF07&axis=rpm
It's fun. Unfortunately, the Q128 is not listed. The closest would probably be the MXUS FX07, which is a 201 motor. It's a little smaller and lighter than the Q128 and since more weight means more copper/power handling, it wouldn't be quite as capable, but close enough. You can build the bike and system as you forsee and add various grades to see "time to overheat" and range.

It makes sense that the extra drag and weight will not make the bicycle experience any better but I am willing to give this hybrid system a try.

Click to expand...

You can try, lot's of people claim they can ride their ebike w/ the power off, but I'm pretty sure the only ones that can do it any distance are the Lycra types w/ thighs like tree trunks and a very lite-weight system(like a 5 Ah batt.)
Note on the controller"Get the one w/PAS even if you don't install it right away. Lot's of newbies say they don't want PAS, but once they try it, they don't go back.

You might want to check pout this on-going thread;
https://endless-sphere.com/forums/viewtopic.php?f=3&t=98517&p=1443600#p1443600
I need to respond, probably tomorrow