Crystalyte TC80 High Torque Motor - but with What Controller??

[Nevin Austin]

Hi Guys -

I am a veteran ebike builder, but find myself in new territory. For many years, I used Crystalyte controllers until the dependability went down. Then I switched to Grin controllers and still do for smaller 48V systems, but this new project I have -- is for a high torque off-road dual suspension machine that need extreme climbing power. At one point I rode a Surron and found that it could almost do wheelies... Which I loved the torque. But not sure if their controller is the solution. Not even sure which one they use.

So, I am wondering if any of you out there might be able to suggest the best (not to big or heavy) controller to bring my 72V system alive with amazing climbing power and torque?? Not really worried about speed on the high-end.

Much appreciated,
Chris

 

[amberwolf]

Depends on the rest of your system. Some thoughts, since we don't know anything about your system other than it is a "72v system", and a TC-80 (hubmotor, but used in a wheel, or used as a middrive?) which is very little info (and nowhere near enough to choose a controller/etc with). (presumably this is a different system from the other thread you have going that you have yet to reply to).

The Surron is a middrive; middrives can be geared for torque or for speed without changing the motor itself, as long as the motor can handle the power required to do the job you need it to, under the conditions you have, while producing the torque you need it to.

Torque in the motor is created by phase current from the controller, and torque at the wheel is created by the torque of the motor and the speed of the motor multiplied by the gearing ratio between the motor and the ground (which includes the size of the wheel, and the gearing itself, whether that is by belt, chain, and/or a gearbox). So it can use less phase current and less motor torque to create more wheel torque. It can also use a smaller lighter motor by spinning it faster and gearing it down more.

If your system is a hubmotor, it doesn't have any gearing besides the wheel size to do this with, so it takes (probably a lot) more phase current to create the same wheel torque, and the controller will have to be able to supply this reliably and continuously for as long as you need it to. A hubmotor, spinning many times slower, will need to be much larger and heavier to create the same torque this way.

Total power at the wheel is about the same either way, and system power should be similar, but the way it's delivered to the motor changes, along with teh way the motor delivers it to the wheel.

The controller creates phase current from the total power taken from the battery, so the battery has to be able to supply all of that power (motor power required plus losses in the system).

Let's say it takes 8000w to do what you want at the motor, and everytihng is in total 85% efficient, so 8000w is 85% of the power the battery must supply. 8000 x 1/0.85= 9412W. 9412W / 72v = 131A. In this example, your battery has to be able to supply 131A at 72v for as long as necessary (so, a continuous rating of 131A at minimum). The controller, if rated for battery current (most are, some are rated as phase current which makes things more complicated to guesstimate), would need to be at minimum a 131A controller.


If you haven't already determined power requirements, you can do some guesstimates of required total power using the ebikes.ca motor and/or trip simulators.

 

[Nevin Austin]

That was a very in-depth and thoughtful reply. Thank you Amberwolf!

I do have some limited space for my battery - but know that I will need to run high current (as suggested) and am shooting for 100A min. Interesting that you devised 131 with the math. I have tried a Sabvotan 100A controller - but it is quite large, heavy and it seems a bit overkill on the amount and type of connection wires / connectors it comes with.. I know they make higher Current controllers and thought about that. The one I have barely fits in my frame!

Since this is definitely a hub drive system - I understand the need to depend on the battery first and make sure the controller can support it. At this point - I am just looking for some suggestions on what alternative controllers might work well on this project. FYI, I have been a Grin dealer for many years and know and appreciate their software tools. And I have been buying and installing their controllers, displays, etc for my more basic systems at 48V - 40A.

 

[E-HP]

I do have some limited space for my battery - but know that I will need to run high current (as suggested) and am shooting for 100A min.
...I have tried a Sabvotan 100A controller - but it is quite large, heavy and it seems a bit overkill on the amount and type of connection wires / connectors it comes with..

controller to bring my 72V system alive with amazing climbing power and torque?? Not really worried about speed on the high-end.

I have two of these, one for backup. Rated 80A battery, 240A phase (but was detuned out of the box), shunt modded to 90A, but I normally limit to 70A, for a safe margin.

https://www.amazon.com/gp/product/B0B8CRXGTW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I bought them for $70, but see the price has gone up to $90 now. APL is using a similar clone on his V4 Cruiser Build, and I think running higher current, so 100A is likely possible. Sinewave/FOC, and you can feel the authority of the high phase amp limit.

I believe these are a clone of the Sabvoton ML7280 , but it's more compact than the 72100.

 

[Nevin Austin]

Thanks E-HP -

Useful info. I thought about trying the Sabvoton 7280. This gives me new perspective. I need to validate size but might try. I will come back and post images of new machine when finished!

 

[Nevin Austin]

Actually - I do have 1 more question about this build. I am looking for a small and discrete basic display that I can integrate on the handlebars. Any suggestions? I have been using the Cycle Analyst for years - but want something smaller and simpler. Something like this (attached). I know wiring and set up can be a challenge - but hoping for a simple solution!

 

[amberwolf]

I do have some limited space for my battery - but know that I will need to run high current (as suggested) and am shooting for 100A min. Interesting that you devised 131 with the math.

That was just a randomly chosen high wattage--you may need much more power than that, or less, we can't know what you'll need with the tiny amount of information provided so far.

(sorry if the below sounds "insistent" but it really does take more info than you've given to choose stuff to "suggest the best (not to big or heavy) controller to bring my 72V system alive with amazing climbing power and torque".)

So you must determine the actual power required for the job you need the system to do, under the conditions you need it to do them under, before you can choose your controller, motor, etc.

Then you must get or build a battery that can supply that power.

If you don't figure out the power you need first, then you're just as likely to be spending money again buying new parts as happening to get the right solution the first time.

Since we don't know how much power you need, we can't suggest specific controllers.

If I have to guess what you need, you probably need in the 5-digit-kW range of power, continuously, for offroad hill climbing torque as you describe. We'll start guessing at say, 10kw (you might need more), so at 72v that means you need at least 139A battery current. You probably need more than that, because at low speeds and high loads the hub drive is going to need more power as it will be wasting a lot of it as heat instead of moving the bike, so you could need a couple hundred amps from the battery sometimes, at a guess.

Everything is speculation right now, without specific information from you otherwise.

I have tried a Sabvotan 100A controller - but it is quite large, heavy and it seems a bit overkill on the amount and type of connection wires / connectors it comes with.. I know they make higher Current controllers and thought about that. The one I have barely fits in my frame!

Do you know how much current you need to do what you want? Is it less than 100A battery current? If it's more, you need a bigger controller (it might not have to be physically larger, but it would have to handle the higher current and power).

Since this is definitely a hub drive system - I understand the need to depend on the battery first and make sure the controller can support it

No, you need to determine the power required first, then get a motor and controller that can supply that, *then* get a battery that can supply more than that (because it will take more battery power to create the motor power required due to inefficiencies).

. At this point - I am just looking for some suggestions on what alternative controllers might work well on this project.

There is not enough information here yet to tell you that.

I am looking for a small and discrete basic display that I can integrate on the handlebars. Any suggestions? I have been using the Cycle Analyst for years - but want something smaller and simpler.

Well, the CA isn't a display in that sense, so if you want the functions it provides other than battery information and speedo, you'll still need it, whether you use it where you can see it or not.

For a display that's just battery info and speedo, you can get those separately pretty small.

If you need them together, or need them to integrate with the controller, such as to access it's settings, etc., or receive information from it and display it, you must first choose the controller, then find out which displays (if any) that it is compatible with, and get one of those, because displays and controllers are not generally intercompatible.

So you have to decide what you need the display to do for you. If you need it to do something that none of the displays available for a particular controller can do, you have to choose a different controller that does do those things with the displays that are compatible with it.

If it sounds like this is all complicated...well, since very little is standardized about all this stuff, then yes, it is overly complex to figure out. :/


FWIW, things like displays, and any functions you need the controller to have (like user programmability, or regen (and how do you need that to work--variable, or just on/off?), FOC (or if not, sinewave or trap), size limits, budget, connector types you prefer or don't want, etc., will all also limit your controller choices.

So unless you define those things, too, it's tough to suggest specific controllers to do them.

If the only thing that matters is that it can drive the motor with enough power for the conditions you need it to do so under, and you will work around all the other limitations, then we just need to know your power requirements, and then list some controllers that will do that, then you can decide from among those that best fit your other requirements.