GoldenMotor.com Forum

He gave me a cable to connect the bike to the computer to check the various settings... how do I check the BMS parameters?

The BMS is unlikely to be user configurable unless it has Bluetooth connectivity which allows user to change certain parameters. Most BMS have a sticker on them stating the maximum and continuous current figures and voltage etc.. As the BMS is usually hidden inside the battery casing, there may be a sticker on the battery casing with the voltage and current figures etc. if you're lucky.

I can basically stop it with my feet when I take off but it feels like it gradually gets better in a few meters... the problem is, if the throttle response is so poor, you can only use it uphill if you have enough momentum.

I have just been looking at the dynamometer data for the 48V version of that motor and it shows ~24Nm of torque with a 176 Amp current draw. Unfortunately, I suspect that your bike may have the VEC300 controller that is only rated for 120A @ 48V or 100A @ 72V. The 48V 5kW motor is only likely to produce ~ 13Nm of torque with a 120 Amp current draw.

The gear reduction on your bike is similar to the original Electro-Motion trials bike, which also had a two stage gear reduction. 
The primary stage was via a toothed drive belt, but the secondary stage utilized a more convention chain and sprocket drive:


The primary belt reduction ratio was ~2:1, and the secondary chain and sprockets gear ratio was 6.45:1 (9T:58T):


This provided a combined total gear reduction of ~12.9:1.

After carefully studying your previous picture, your bike appears to have a 3:1 primary reduction (14T:42T), but as the rear sprocket is not shown I can't tell what the secondary reduction is (14T:??T).
If yours has a 42 tooth sprocket on the rear wheel, that would give a 9:1 overall gear reduction ratio, which (according to my calculations) means the torque at your rear wheel should be ~117Nm @ 120 Amps.
If it's a 56 tooth sprocket on the rear wheel, that would be a 12:1 overall gear reduction ratio, which should provide ~156Nm of wheel torque @ 120 Amps.

I've guessed that your rear tyre's outer diameter is likely to be ~600mm (24"), in which case a 42 tooth rear sprocket should provide a forward force of ~384N (39kg or 86lbs), which I reckon should be sufficient to propel a combined 250kg load (bike and rider) up a 11% slope.
If your rear sprocket had 56 teeth it would provide a forward force of ~512N (52kg or 114lbs) that should be sufficient to propel the same 250kg load up a 19% slope!
In ether case, your motor is obviously not drawing anywhere near 120 Amps from a standstill, because you would not be able to stop it so easily with your feet if it was.

You should be able to use the PI-800 programming software with the USB programming cable to read the parameters from the controller. If you can then attach some screenshots (or the exported *.FOC file) I will take a look at your existing settings to see if there is anything obvious that needs to be changed to hopefully improve the low speed torque/power.
       
If you need the USB Driver, it can be download from here.

Alan

P.S. I don't know what voltage your battery is, but I'm guessing that it's a 20Ah pack (Ampere-hour = storage capacity) rather than 20Amp (Ampere = unit of electric current).
 

Hi Triad andto the forum.

If the motor is cutting out under load, I would say that the battery (or the battery's BMS) may be unable to deliver the required power under maximum load, and the BMS is simply cutting the power going to the motor to protect either itself or the battery.

If the battery has one or more weak cells, the weakest cell voltage can be pulled low enough under load that it reaches the minimum permitted cell voltage setting in the battery's BMS, which would trigger the BMS to instantly shut off the power going to the motor.

If the maximum current output of the battery's BMS is being exceeded under heavy load, it is possible that the BMS will also cut off the power to protect itself from being overloaded.

A suitable voltmeter attached to the battery connections on the controller would allow you to see what is happening to the supply voltage under load.
If you have a 48V battery and the voltage at the controller drops to 42V (52V for a 60V battery or 63V for a 72V battery) just before the motor cuts out, it is likely to be a weak cell/cells in the battery.
A new battery of a similar size, but with improved cells that can deliver at least 120 Amps, may be required to extract maximum power from the motor.

If you don't want to purchase a higher power battery, you should be able to gradually reduce the Battery drawn current (A) setting until the battery no longer "turns off" under full throttle.
However, if it's weak cells that are causing the problem, these cells will probably continue to weaken, causing the cutting out to eventually return even with the reduced battery current settings.

If the voltage at the controller does not drop as low as 42V (or 52V/63V for 60/72V battery) before the motor cuts out, it could be the BMS that is causing the problem. It could be faulty, or it may need to be upgraded with a BMS that has the required current output (provided the cells in the battery are able to deliver the increased current.)

If the voltage at the controller does not drop when the controller cuts out, it could simply be that the stall protection is being activated by the controller itself.
If this is the case, try increasing the stall protection time (s) setting in the controller to see if it improves the cutting out.

Alan
 

For all the bells and whistles of the new EzKontroller; blue tooth interface, integrated cooling etc. I can't find a way to import & export settings.

With even more settings than the VEC-series, that had an import/export feature it seems really strange GM have omitted such a feature.

Is there anyone out there who has been able to export the settings from the EzKontroller?

I didnt pay attention and purchased BBOS2 motor and found out that it don't fit.

My bike have a BB30 bottom bracket, I don't have caliper but with eye-balling on ruler, BB width 83.25mm, inner diameter 42mm.

my bike is Cannondale BOTE1, it’s a fat bike

What do I need to do to salvage this build? Please help me.

Can I use the Lekkie , Press fit 41mm BB86/92 adaptor for 68mm, to make the BBOS2 fit my bottom bracket?

It’s my fault for not paying attention and didnt do much research on it.
Please help me with my build, thank you

Hi there,

First of all : Unless the motor rpm somewhat matches the rpm of the prop, you need some kind of gear box.

The peak power of the GM 10 Kw BLDC is at around 3700 rpm, which is way to high for a 14x18, so unless there's gearbox inside the leg, one would bee needed.

I've gone through the same thing although with the motor mounted as an inboard, thinking that the great torque of an electric motor would solve that. Even though I had water cooling blocks mounted on the VEC-500 if sometimes got above 75 °C.

During my build of a reduction gear I swapped the VEC-500 for the EZ-kontrol B48-1000. Now the controller barely gets over 40 °C after several hours of use and the motor tops at 65 °C.

All reasoning and calculations about the reduction gear is documented in this blog post. Google translate available.