Dousi said:
this is the scooter I have:
Ah. Well that is the same one I see listed as only 1000w motor in a number of places, even though it is listed as an 1800w scooter. They don't specify the controller at all, though, so it could be 1800w.
But until you put a wattmeter on it, and measure what it actually uses, I wouldn't really believe it. You can get cheap ones; there's a number of threads about wattmeters that will help you find the best one for your needs. That's the first thing I'd actually do, so you then can figure out where other things can be improved.
It has an CH12K05-A Controller 1800W and a CHD01-C BLDC Motor with 1800W, 5400rpm
Battery is a 48V 12ah SLA.
FWIW, whenever you're actually using 1800w (if indeed this system is capable of it), you'll be pulling over 3C from those batteries (nearly 37A), which can be hard on little SLA. Most of them were tested at slow discharge rates of 1/20C, or 0.05C; this is what their capacity is rated at, meaning you will only get 12Ah at that low rate, and high rates like this will usually only let you get about half that capacity, at best. Then since it's bad for them to discharge past about 50%, you really only get about 1/4 their listed capacity, so it's like having a 3 or 4 Ah battery pack for all that space and weight.
They'll also generally sag a lot in voltage, so you wont' really be getting 1800w out of them (or else the current will increase, being even harder on them), so your speed drops when under that kind of load, sometimes quite a lot, and increasing throttle won't help.
Depending on the space you have available, something like RC LiPo might be the best option for high power...but lifespan is short, and there is more risk with it than with some other battery types (which don't have the same power capabilities, for the same size pack, however). What you end up with will be determined by the actual current and power needed by the system (which you have to measure under the worst loads, like the hill), your budget, your available space, and your willingness and ability to deal with risk (fire, etc) and DIY.
Yesterday I drove uphill and it was a very rough ride, as if the controller cant control fine enough for these "low" RPM I needed for the steep (10°) hill.
That usually means that the system is overloaded, unable to supply enough power to keep your speed and prevent overheating the motor and controller, and overstressing the batteries, if you can't keep up a high RPM to have at least 50% or more of the motor's unloaded speed. A couple of things can happen; the hall sensors, if the motor has them, can overheat and then the controller doesn't get correct position sensing, so it sends power to the mtoro with teh wrong timing, and it feels rough. Or the cheaper types of sensorless motor and controller can have troulbe under high loads and slower speeds with reading the pulses of the motor feedback and thus creating the right timing of signals.
If you have a pointable IR thermometer, you can measure the actual motor casing temperature, and controlller temperature, etc., at the top of the uphill ride, after having ridden around the same amount you usually would, where you see the performance problems.
One ohter thing that can cause a rough ride is if the battery voltage drops so much that it is below the controller's cutout. If it has a fast response time to it's LVC, it'll cut out, then the voltage will go back up, it'll turn bakc on and start running again, then immediately cutout from the load causing voltage drop, and cycle thru this until the load is removed (till you're not going uphill).
would a Kelly Controller help here? is a true Sinewave better for low rpm torque? It felt as if I can feel the controller switch from one phase to the other.
You'd get the same problem, if it's a sensored controller and it's overheating, or if the motor is that overloaded.
Before considering a Kelly, you should read around the forums for troubleshooting threads on that brand (and others, like Sabvoton, etc), to see the kinds of issues you may be getting into.
For low RPM torque, you need more power, if you mean low motor RPM. If you mean low wheel RPM, then more power, *or* lower gearing, so the motor spins faster for the same wheel RPM, and is more able to supply more power.
Sinewave isn't likely to make much difference there (sometiems it makes it worse with some controller/motor combinations). There are also several kinds of sinewave; some are true FOC that constantly calculate the motor waveform based on the motor's feedback, some are just lookup tables with a rough sinewave shape, that don't adapt to the actual motor conditions. Which one works better depends on the motor and condtions, but the non-lookup-table-type will require more information about the motor (inductance, resistance, kV (RPM/volt)), which if you don't have you'll have to measure, unless it has an "autotune" function to at least get you close. This is more complicated to setup, but usually works better once it is properly tuned.
The catch is that at low RPM, like especially from a stop, if it is a completely sensorless system, it may have trouble determining actual motor conditions since there's not enough feedback yet. Some of these use sensored start / sensorless run, and they work better (sometiems a lot better) at zero speed and low speeds, once the system is tuned.
If you don't want to deal with tuning, the lookup-table-type dont' need to know anythign about the motor, but they also don't adapt to motor conditions so may not work quite as well in some systems.
First thing I'm gonna do is change the chaindrive to belt
Before you do, make sure you look up some of the belt-drive type threads for various systems (not just boards/scooters), as there are some things to consider when sizing belts, sprockets, etc. For instance, you'll need a wider belt to do the same work as a narrower chain, probably twice as wide or more. Other considerations include bend radius for specific belts and types; tighter bends means faster wear and more problems. Tension is another issue.
and reduce the Reduction ratio to get more torque and less speed.
That might help with motor overloading, but if it still can't keep up enough speed on the hills, it'll still have the same problems there.
