Stromer STX1 -> Hack

A while ago I’ve bought a water-damaged stromer STX1, at auction, with the intention to fix, and ride it. Contacted stromer for parts but they weren’t really helpful. As a matter of fact they told me to bring it to a dealer and let him fix it. Total costs €3500. What they charge for separate parts was way over the top, and on top of that, the software blocks after market parts such as non-stromer batteries. They really made me feel like a sucker. My bike but I’m not allowed to do anything to it without their consent.

Anyway, I took it apart and like Oscar Goldman said: “we can rebuild him. We have the technology. We can make him better than he was. Better, stronger, faster”.
Although... I don’t know yet how. I might need some help. Already I’ve bought a TDCM hub and an aftermarket controller.
And today I did some testing but I cant seem to get the battery going. I've attached a voltmeter to it but there’s no readings. I suppose a trigger is needed on the battery it with a signal of xx volts.
The battery was fully charged and already been tested in a different stromer.

Any ideas how to get the battery going?

Regards, Harm

Not much experience with that model, but does the battery have a data connection? It may require a command to enable. The command may also just be simply a voltage applied to a line. You may need to measure on a working one to see where the signal is.

Any pictures of the battery insides?

Yes, there is a battery a data connection with four wires (see picture)
And I may be able to get my hands on a working one this weekend.
If so, I'll try your suggestion.

Thanks & regards,
Harm

So it's like an apple product basically, which is pretty much what i suspected from stromer.

What's the voltage on the battery? hit it up with a voltmeter and see if it's too low.
If it's fully charged, then the BMS suicided itself and you will need to retrofit a new one.

I have a Bosch battery here that did the same thing. All cells at 3.8-3.9, but refuses to charge. Only 1.5 years old as well. Time to rip out the poorly designed proprietary BMS..

What I would do, and why

Buying a hub motor kit and install it on the frame after sripping off the actual motorization. Stripping the battery off all electronics, to plug it direct on the kit controller (eventually adding a BMS depending on battery cells type and chemistry). Or, buying Lipo bricks to build a new battery, and sell this one to some owner of a Stromer bike.

Proprietary systems can be tricked to work, but you might have to find a new trick everytime it will fail in the future. Also, it is likely to be more complicated to diagnose when it fails.

Hmmm...

If there is no output from the battery, then there would be nothing to power the display or controller to send data. Seems like the BMS is bad. The BMS likely sends data to the controller telling it that it's a genuine battery and enables the controller. If you could read the data stream on a working one, it may be possible to program an Arduino to spoof the data.

Replacing the BMS with a generic one would make the battery work but you probably still need that data string to enable the controller. A new BMS and controller are not that expensive.

Where is the controller located? The stock motor might work with a generic controller.

It probably will (been done with a number of Stromer rear hubmotors by UUmotor here on ES and elsewhere), but without the Stromer controller you lose the torque sensing PAS, if taht's a feature you like (assuming this model has one like the others I've seen, mounted in a recess at the rear dropout).

I believe the STX1 came with the TDCM Ulta, power 48, motor. It has the controller inside. It's very heavy but powerful and totally quiet. Well worth trying to fix. Agreeing with Amberwolf, if you want to keep all the feature of the STX1 you are at Stomer's mercy for part$. You also can't be sure water damage hasn't messed up inside the hub.

I suggest you open the hub and take a look. It's a pain since the spokes have to be removed and you need a 3 jaw puller. You find instructions and photos if you search this forum. If it doesn't look good, consider disconnecting the controller and connecting directly to the motor's 3 phase wires, and 3 hall sensors (5 wires), Bring that 8 wire cable out and connect to any external controller, throttle and a 36v or higher battery for the purpose of testing. The internal controller is potted and difficult to remove, so just leave it (not connected). If the motor works smoothly, then build a bike that you will really like with decent but inexpensive (compared to Stromer) parts. The bike won't look quite as nice since the controller is not hidden, but you can set your own power and speed limits, chose your own accessories.

I just built the tandem pictured below with a scrapped TDCM Ulta, power 48, motor, a 1500w dual power external controller and 54v21ah battery. It is an amazing ride. Well over 36 mph in high power, and very efficient at 22mph in low (50+miles).

That looks very similar to my A2B motor. It certainly was a pain to remove all the spokes and pry the motor halves apart but now that I have the right tools it wouldn't be that bad. I cut off the stock controller and went with an externally mounted one with much more power. Totally worth it but a lot of work.

Firedog said:

It's a pain since the spokes have to be removed and you need a 3 jaw puller. You find instructions and photos if you search this forum.

Click to expand...

Somewhere in my posts is a thread about one of the UUmotors off a stromer, that opens like this, showing takeapart, including internal pics/etc. I suspect it's internal controller is ok, but can't test it without the rest of a stromer.

It is potted; I've considered digging out the potting to get to the gate drivers, and hook up the MCU section of a generic controller I've got that has blown power section. Would probably have to move the whole controller outside the wheel to make that work, running hall and phase wires out of the motor thru the axle slot to it. (if it doesn't work I can still use those to be driven by another controller).

The internal controller is potted and difficult to remove, so just leave it (not connected).

Click to expand...

On mine, while it is potted, it's just held in with a few screws so not hard to remove, IIRC.