Speed limited

[Leon525]

None stop issues with stealth bomber b52.


Originally bought it with a dropped cell on its original battery. I fitted a new battery 72v 45ah 100bms but now the bikes limited to 33mph on stand with no weight. It's clearly been limited by something. These bikes do 50mph from factory.


It's set in competition mode at 6200 watts and a speed limit set at 95mph so no issue there.


It's very smooth and has nice power delivery up to 33mph and will just hold there no issue. On the throttle it seems like there's another quarter of travel left which doesn't actually do anything.


There's no errors showing on display


What is likely to be my issue here. I'm thinking about just fitting a new controller but could it be my motor something else.


Am I right in thinking the lower the shunt omhs the more power could this be something?


Any help would be appreciated.

 

[E-HP]

How fast was it before the battery issue?

 

[Leon525]

Bought it with the issue. I didn’t know at the time.

 

[E-HP]

Ah, your other thread made me think you had been using the bike and the battery died.
“My bomber battery dropped a cell it’s a 72v 18ah lifep04 battery.”

Did you ask the seller how fast it ran on 72v? Maybe the previous owner opted for a slow wind motor for better torque for his riding style. Do you know the motor turn count?

 

[amberwolf]

Is the controller a torque-modulating type, or speed-modulating?

The former controls the torque (current) of the motor, modulating that with the throttle; most FOC types work this way. These don't usually behave as expected when unloaded, because of the phase-current/etc monitoring and feedback, limits, etc., even when they work perfectly riding them around. You're commanding a certain (phase-) current with the throttle, so they behave differently when riding it than up on a stand where there's no load to demand that much current.

The latter is the typical controller that modulates speed with the throttle, and these work the same offground as while riding, as you're just commanding a speed with the throttle, and the controller does whatever it needs to do to spin the wheel that fast.

 

[Leon525]

Is the controller a torque-modulating type, or speed-modulating?

The former controls the torque (current) of the motor, modulating that with the throttle; most FOC types work this way. These don't usually behave as expected when unloaded, because of the phase-current/etc monitoring and feedback, limits, etc., even when they work perfectly riding them around. You're commanding a certain (phase-) current with the throttle, so they behave differently when riding it than up on a stand where there's no load to demand that much current.

The latter is the typical controller that modulates speed with the throttle, and these work the same offground as while riding, as you're just commanding a speed with the throttle, and the controller does whatever it needs to do to spin the wheel that fast.

You could be onto something here. I’m not sure of any of the inner details of the controller as stealth will not share information like that and there’s nothing on the controller.

The throttle is 4 pin and I find most seem to just be 3?

 

[E-HP]

If you went from LiFEPO4 to lithium ion, and even if you didn’t change any settings, the bike should have run fine on the fully charged pack, with slightly less speed, assuming that both the new pack, and used bike are capable. You’d need to adjust the lvc, or the battery voltage settings to have the right battery level, etc. later, but even without that, it should have run fine. Who do you trust more? The battery builder or the bike seller? Something isn’t adding up.

 

[amberwolf]

You could be onto something here. I’m not sure of any of the inner details of the controller as stealth will not share information like that and there’s nothing on the controller.

Without markings on the controller itself, you can tell at least if it is torque control vs speed control by how it reacts to a throttle input with the drive wheel offground vs on-ground. If it always modulates the speed proportionally to the htrottle position regardless of the load (even if hte speed is far lower with the load than without) then it's a speed controller. If the speed doesn't respond proportionally to throttel position especially without a load, it's probably a torque-based controller that's modulating current by the throttle.


Alternately you can open it up and see what markings, if any, are on the board inside, and try to match those with known brands/models, at least in pattern if not specifics.

Additionally, the torque controllers are usually FOC and almost always have current sensors on the phase wires, while the other type don't usually have those and only monitor battery current with a shunt in the negative battery input line.

The throttle is 4 pin and I find most seem to just be 3?

All sorts of throttles have different numbers of pins, depending on the specific functions it has, and any additional controls, switches, lights, etc. But the throttle itself doesn't tell you anything about what kind of controller there is.

 

[Leon525]

I’ve decided to replace the controller with a sabvoton 150.

 

[E-HP]

Well you mentioned this in your new thread, which is good info.
“I’m a newbie to all this but finding it very enjoyable.”

If you want to do the DIY thing, then you need to learn to troubleshoot rather than using the guess and replace method, which is very costly. You should also have a multimeter, soldering iron, and/or crimpers.

The very first test to perform if you suspect a speed limit imposed by the controller is to test the no load speed vs the loaded speed. That will tell you right away if the speed is “ limited”. If it’s 33mph with the wheel off the ground, then it’s limited by the controller. If it’s faster, the there is no speed related limitation.

That leaves power or motor windings. It takes right around 1300w to hold a steady 33 mph. If your controller can put out more than that under full acceleration or up a hill, then you aren’t power limited.

If that’s the case, then you may have a slow wind motor, in which case, then switching to a faster wind motor, a higher voltage or applying field weakening would be your options for more speed. The first two are preferred if you always need that speed, while the last is good if you only need the extra speed occasionally due to greater consumption/reduced efficiency. Most sabvoton controllers can run FOC and apply field weakening.

I have a work in progress newbie thread in my signature, if you want to read while waiting for parts. There are a few good links, plus some basics. It’s mostly info gathered from this forum.

 

[Leon525]

I have been on the bike and it does seem to move very quickly, but the speed on the display is extremely laggy you need to wait a few moments for it to catch up and by that time I’m on the brakes already and also looking down and not where your going is proving difficult ha.

I’ve spoken to another bomber owner and they’ve recommended me to change the controller for the sab 150 so that’s what I’ve done. It can also get more use out of the custom battery I had made. I’m pretty sure the bms in the stealth is only 80amps. So my battery has more potential and the sab controller will be able to release the power.

 

[E-HP]

Did the other owner have the same motor?

Looks like the 3T Crystalite has a KV rating of around 9.

CRYSTALYTE motor 5300 to 5400 Winding Electrical Information

This thread is to sort all MEASURED caracteristic of the X5 motors after all.. it's the most powerfull hub motor we can get for bicycle...! Every time i dissassemble one i carefully measure and note everything about them that is under the cover. ( all with calibrated fluke equipment)...

endless-sphere.com

Looks like with the new 150A controller you’ll be good for 40mph, assuming a 21” rear tire diameter (without field weakening) with the 5403. Fully charged to 84V, and running. 26” diameter rear tire, it hits 46mph, so field weakening would get it up to 50mph.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

However the 5302 2T Crystalite motor would do 50 mph, all else being equal (21”, no field weakening).

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

 

[Leon525]

From factory they did around 50 mph.

 

[E-HP]

Hopefully you bought the bike really cheap, or the seller can provide a partial refund for the controller.