TranzX PAS to throttle?

Hi All, I'm converting a Hawk Classic Sunbeam. I have a near-complete TranzX system laying around. 36V 250W hub motor (F16 I believe), 36V battery + Tranz Controller and display. The battery was in not so good condition - but I managed to get it re-charged from a near dead state. Display turns on and things look OK. (I think I need to "re-set" the battery by shortening the two orange wires?)

I have almost all parts, apart from the disc for the PAS sensor and the small bracket. I do have the sensor though. Now will it be possible to convert (or configure) the TranzX to use a throttle, and not a PAS ? I cannot find anything about the TranzX system and modifying it..


..I have ordered a KT 36/48V controller that I will use once I have verified that the bike is a good base for an ebike. I also have planned to have a 13S3P pack build using 21700 4800mAh cells. Do you think - if used with common sensor) the motor will be able to be used with the higher voltage?

The throttle connects to the controller, so if you are replacing that, just make sure your new one supports a throttle.

As for the overvoltage, not very many people AT ALL choose to overvolt a 250W motor, there are good reasons for this.

As for whether or not it will work for you in particular, that would require you supplying a LOT of additional information, and if you do not already know exactly what those parameters are, then DON'T do it.

What are the good reasons?
I don’t mind providing the extra info if needed..

As for the throttle, the original controller does not have a throttle input, just the pas sensor.

You are replacing the controller, so the original no longer matters. Keep the original, and no throttle with no connector. Pretty straightforward.

Unless you are a competition-grade cyclist, and have flat ground, an over-volted small motor will melt itself from being unable to run at the indicated RPM due to minimal torque output. Unless you started with a very low-speed motor in the first place. Or use very small wheels.

Also, be EXTREMELY careful with the battery, a lithium pack which has been at very low voltage is a constant, and high, risk of fire. ESPECIALLY when charging. Monitor personally, and constantly, and keep away from all flammable materials. Sleeping while charging such a battery may be the very last mistake you ever make.

Yes if I decide to go 48v - then I will change the controller. That has the throttle input, so no issues with that. I was courious if the original TranzX controller had a Throttle input that was not used..

I live in a country where everything is _flat_ I might have 10m level changes on my daily commute. I currently use an old Hadi Teherani ebike with a brushed motor and a puny 180w that I'm looking to replace. On top of that I also use my Xiaomi M365 scooter with a 12S battery pack and upgraded firmware. That motor takes the higher voltage quite well, so I would assume that the ebike motor would also be capable ?

As for the battery pack, yes - I slow charged it with 0.5A outside far away from anything flammable. It is @ 4.089V now, and no hot cells.I _never_ change my batterypacks during the night. (Well the car gets charged during night, but that is parked outside)

Ah, OK. It is possible that the controller has circuitry for throttle, but it is not connected. You would need to examine the internal solder pads and markings, or ideally get a schematic. Many such controllers do, but not all. You could also use new controller with the 36V battery, they are fairly inexpensive.

The upvolted scooter likely has much smaller wheels than the bike. The wheel essentially acts like a gear. Large (er) wheel is like constantly climbing a hill. Would recommend a temp sensor, this needs to be internal as exterior of case is much, much cooler than, and insulated from, internal heat in the windings, where the melting and burning happens.

The smaller motor just has less safety factor for over-volting. It can be done but when you find out it doesn't work is when it will never work again. Not too expensive to replace, though. Battery is main expense, and if you build or buy a new one, adding a new motor is not too bad.

The reason I'd like to try out the TRanzX controller is that it connects directly to the battery - that makes my install slightly easier to do "stealth". I do have a KT controller as well - but it is more work. Especially considering i do not know if the Hawk Classic is a good base for an e-bike or not.

I have another challenge. I have everything connected, apart from one plug in the wiring loom. It is (probably) for a sensor, it shared the 5v feed and ground with the PAS, but has another signal wire. The plug is situated just next to the PAS plug in the wiring loom.
I have tried to search for TranzX wiring diagrams almost everywhere, but I cannot find any. I do not know what bike the systems comes from, so I cannot just find another identical bike and look at that.

Any ideas to where I can get some schematics of it ?

I did not try logging into the TransX website, but might be worth a go.

Some problematic info there, though.

First, it is German-made. Which likely means that while hi-quality, it is also over-engineered and needlessly complex.

Second, it mentions using the Canbus communication protocol. No specifics, but this often means proprietary communications between controller, display, battery, and/or motor, locking you in to their equipment, or requiring work-arounds, if available. And they might not be.

Any "extra" wires anywhere are likely to be related to inter-component communications not available on replacement parts, but probably mandatory for function.

A bit confused by "controller connects directly to battery." They always do. Do you mean a direct connection plug with no wires, if so, how many pins? If wires, how many?

Your bike appears to have an internally geared rear hub with only one small gear on the crank. Unless your hub is a front mount you will loose the rear hub and pedal gears will be way low for any decent speed, even on flat ground. Good for a front motor, though, at least from appearances.

Ahh yes you’re right, when I say it connects directly to the battery, then I mean there are no wires - you click the controller into a plug directly. There are 4 wires, +(36v), ground and two communication wires.. Yes it is a canbus system, but that is only between the display and the controller I recon?

I managed to get a wiring diagram for it, the loose sensor is for a torque sensor. It is attached to the dropouts for the rear wheel. Now since I’m fitting this to another frame, I do not have room for it on the frame. Remeber I’m just using the ocmplete TranzX system from another bike to get a Hawk Classic Hudson converted to an ebike. The Hawk has a 3 speed freewheel rearhub. The motor is in the front wheel. The gearing might bee too low, but first step is to try it out as an ebike. If that works, then I can start upgrading.

What I *think* I could do..

I suspect the torque sensor to output something between 0 and 5v - since the feed for it is 5v. Now the display has a calibration routine for it, I *hope I can spoof this. There are two steps, first unloaded the display is supposed to read between “200” and “600”. The step to is loading the pedal with 10Kg and highest gear. Here it is supposed to read between 45 and 95. By using a variable resistor I *should* be able to spoof those readings so I can get it “calibrated”. Next step - how does it act if I just use a fixed resistor after it has been calibrated? I *hope* that I can trick it to see a constant torque (max) to give the motor maximum power regardless of how hard I pedal. (Effectively using PAS only). But as you say it is German, so heavily overengineered.. I fear the controller monitors for sanity on the sensors.. if the torque is perfectly constant it might detect a faulty sensor.. Well only one way to find out I guess.

I just did a test, made a voltage divider that would give me 3.1v. Tried the “cal1” on the disdplay - but it would not give me a value - just stayed at 0. Reversed the voltage divider so it would give me 1.8v - still the same 0. :/

Well, if the connection from the controller to the battery has two comm wires, I would think those are not for the display. Downright Bionx-like. They went belly-up for a reason, also.

As for the sensor, I think I have seen some similar hacks referenced, I have no interest in PAS sensors at all so have not paid much attention. There is quite a bit of variation in voltages and methods of operation, from what I have seen. There is a fairly good breakdown of operating parameters for at least one type around here somewhere.

I decided to ditch the tranzx system completely.. I'm going for a TSDZ2 instead.
The reasons - I will have to hack'n'slash to get it work. I would have to get a rim brake if using a hub motor. Getting a rimbrake that will fit over my 80mm fenders is a bit of a pita, and they are not very good. I'm switching back to the roller brake setup the bike came with and then going for a TSDZ2.

..I'd rather use the motor and my KT controller for my Hadi Teherani bike that currently has a brushed hub motor and puny 180w.

Thanks for all the inputs - it gets too hackery in the end..