Special bike (old trial) converted but weak

[Bikemad]

Lowering the maximum drawn current did the trick but I had to lower it to 100 (default setting was 250!).

I think you may have lowered the wrong setting as the 48V VEC300 controller is only rated for 120 Amps of battery current.
However, the Phase current is typically a lot higher than the battery current, as Phase current is delivered in a series of high current pulses supplied directly from the controller's capacitors (the VEC300 controller is rated for 300 Amps of Phase current).
The *.foc file I have saved from a VEC300 controller shows both the Rated and Phase current set at 280A with a battery current of 110A.

Try resetting the Maximum phase current (A) and the Rated phase current (A) to 250 and leave the Battery drawn current limit (A) at 100 and see what difference it makes.
If it starts cutting out again, try lowering the Battery drawn current limit (A) until it stops.

However, if it does improve the torque without cutting out, it might be worth increasing the Phase current to see if you can improve the torque at low throttle.

Alan
 

[Triad]

Will do, but I'm pretty sure about the parameters... will report back asap!

[Triad]

Nope... tried as you suggested, the bike will freeze up again as soon as I raise one of those values. 

[Bikemad]

If you currently have the Boost enable set to 1:Enable and the Boost Mode set to 1:Auto Mode try disabling it (or lowering the Boost Current (A) setting to 100) and see if it will then work with higher Phase current settings.
If the Boost current (A) is set higher than your battery's safe maximum current output this could still cause the battery to shut down as it (presumably) overrides the Battery drawn current limit for the set number of seconds.

If you can save (export) the parameters to a .foc file and then attach the .foc file to your next reply, it should enable me to see exactly how the controller is currently programmed (provided the file imports correctly into my version of the programming software.)

Alan
 

[Triad]

Yeah, I tried but unfortunately the computer I'm using to set the controller up has an old mail program, I should log in with gmail to put the .foc file here.
I think I have the boost in auto mode. But since the problem with this bike was always the start from dead stop, do you think it would be stronger if I disabled the boost and raised the phase current from 100 to 250 (in case it works)?

[Bikemad]

Unfortunately the computer I'm using to set the controller up has an old mail program, I should log in with gmail to put the .foc file here.

If the computer you are using has internet access, you should be able to access the forum directly from that computer and simply attach the saved .foc file from where you saved it on that computer. 

But since the problem with this bike was always the start from dead stop, do you think it would be stronger if I disabled the boost and raised the phase current from 100 to 250 (in case it works)?

You'll just have to try it and see what happens. Unfortunately, it is probably going to require a fair amount of trial and error adjustment & testing to determine the best combination of settings that will give the best performance without the battery/BMS cutting out.
Assuming it is not a weak/faulty cell causing the problem, with the Boost function disabled and the battery drawn current setting set lower than the battery's maximum continuous current output, it should not cut out.

Once you have determined the optimum setting for the battery drawn current with higher Phase current setting you can then try re-enabling the boost function.
Start with a short duration and then gradually increase the boost current setting until the cutting out starts again, then gradually decrease the boost current setting until the cutting out stops.
It may then be possible to then increase the duration of the boost to allow more power for a slightly longer period of time (unless the cutting out starts again).

Make sure that you save a backup copy (exported .foc file) of the best performance settings and keep it safe in case you accidentally reload the default settings. 
Use a filename that clearly describes the saved settings, i.e. "max power occasional cutting out.foc" or "stable performance but weak torque.foc" etc.

Unfortunately, if the cutting out is caused by a weak cell's voltage being pulled too low under load, the cutting out problem is likely to worsen as the battery becomes more discharged.
Although the cutting out problem may have been cured when testing with a fully charged battery, you could well find that the cutting out problem will quickly return again as the battery voltage begins to drop slightly during normal use.

Alan
 

[Triad]

I'll try to disable the boost function and raise the maximum current... but do you think the controller is the "weak link" or the battery comes first?
How big of a battery would it need to work properly?
Will report back later, thanks again!

[Triad]

No luck... it goes in protection as soon as I raise those values, even without the boost.
One question: this bike is set so there's a small 12v battery to activate lights and the "starting relay"... but I've never seen another converted vehicle wired like this.
Would it be easy to remove the relay and the battery? 'Cause if it's down, the controller won't work.

[Bikemad]

I'll try to disable the boost function and raise the maximum current... but do you think the controller is the "weak link" or the battery comes first?
How big of a battery would it need to work properly?

If the controller was cutting the power it should also be emitting one or more error codes (a series of audible beeps & LED flashes) but as you have not mentioned any sign of an error code I'm assuming that it's the battery/BMS that's the "weak link", not the controller.

It is not down to the size of the battery, it's your battery's inability to deliver the required power that is most likely causing the problem.
To produce the maximum power from your motor/controller setup you would need a battery and BMS that can ideally deliver 110 Amps continuously and 180 Amps peak.
Unfortunately, the limited space on your bike means that you will probably need a custom made battery using high current cells that would fit into the existing battery space.

I think it should be possible to have a 48V 35Ah battery built that could supply up to 200 Amps of power from 140 x 30A 18650 3500mAh cells in a 14S10P configuration along with a 200 Amp BMS in a battery size of around 200mm x 150mm x 140mm (8" x 6" x 5.5") but 30 Amp 18650 cells are not cheap!

One question: this bike is set so there's a small 12v battery to activate lights and the "starting relay"... but I've never seen another converted vehicle wired like this.
Would it be easy to remove the relay and the battery? 'Cause if it's down, the controller won't work.

If it's a high current relay (contactor) that is physically switching a main battery power lead you would need to replace it with a heavy duty (high current) battery isolator switch, but if the relay is only switching the e-lock wires on the controller, it can be replaced with a simple On/Off or key switch.

Alan
 

[Triad]

I guess it's case n.1, otherwise I doubt the guy would have used a battery and a relay. I can hear it click when I turn the switch ON.
Never heard a beep from the controller, though.

[Triad]

Anyway it looks like my modifications to make it more torquey led me to another problem: the transmission.
The motor now spins with some power from a dead stop and the pulleys can't survive. The primary is deformed but the final drive belt is destroyed... the small sprocket spins and basically rips the teeth off 
I'm thinking about converting it to chain, but it would be a pain.

Oh, another question: is there a way to make it easier to go in reverse? I mean, if you need to park the bike and you try to pull it backward, there's a lot of resistence. Is it normal and is there a way to avoid this?

[Bikemad]

Is there a way to make it easier to go in reverse? I mean, if you need to park the bike and you try to pull it backward, there's a lot of resistence. Is it normal and is there a way to avoid this?

The resistance is caused by the extreme gear reduction. A 12:1 reduction increases the torque at the back wheel by a factor of 12, but this also make it 12 times more difficult for the wheel to turn the motor. 

To overcome the motor drag resistance, I would fit a momentary switch (i.e. a horn switch) on the left hand side of the handlebars and connect it to the reverse wires so that you can simply press and hold the switch to engage reverse and then use the throttle as required.
You should also reduce both the Backword speed ratio (%) and the Reverse torque ratio (%) settings to ~25% (or maybe even lower) to ensure you don't accidentally apply too much power or go too fast in reverse.

Alan
 

[Triad]

This project is really a pain... when I got it it was too weak, now that I solved that it's got new problems (the belts not holding up) 

In all honesty I'm thinking about breaking it for parts, maybe fit the parts on a bycicle with shocks. At least it would be "road legal" and I could use it without peoples calling the police