Thursday, 4 July 2019

Mercane Wide Wheel 500W single motor: speed trials

So, its a quiet night with no wind and one of my backstreets here is as smooth as it gets, tyres even run almost silent. So I thought I'd do some short speed trials:

  1. "ECO Mode"
  2. "Power Mode"
  3. and the disable speed limiter in "Power Mode"
My scoot is the Single Motor (500W) variant with an 8.8Ah (422Wh) battery pack.

No point in saying more than that

1. Eco

2. Power

3. limiter disabled (Power Mode)

Observations & Opinion

These are short runs, but I could see that the voltage was buckling in (falling) observably on the unlimited run. So basically I wouldn't like to see this run for long on a 4 bundle parallel pack of cells as you'd likely run it into harmful territory quickly.

Why? Well I've been playing with a bicycle energy requirements calculator and found that if I calculate the rolling resistance of the wheels (and sadly for scooters, smaller diameter is a bad thing because its a scalar in the equation : half the diameter = twice the resistance) and plug that in I get remarkably close to what I experienced last night (parameters).

Looking at case #1

We see that I need under 500W (its a single 500W motor model) to maintain that speed (436W actually, sorry I cropped that badly). This is well within the limits of the system.

When I used Power Mode I got this data:

meaning that its using about the full 500W (lets allow a little margin here and also observe that my battery was showing 52V when I started).

Now onto the "unlimited" we see an interesting picture emerge

... and the motors "peak" power is given as 800W. Meaning that if you use it in unlocked for long you'll break something soon enough. This supports my concerns when I've experimented with it and seen the voltage start dropping very fast. I guess it would be race as to which failed first, battery or motor.

As I've already established it works quite acceptably with the Cruise Control, thus I sort of like using it if I know I may need a "dash of speed up my sleeve" but can reliably set the speed lower and not punish the batteries (and maybe motor?) using the thumb trigger. However the scooter resets the "over-ride" made to "unlock" the "full power", which looking at this is quite sensible.

This supports my view that if you think you need more power, get the model with more power in the first place. In this case (Mercane) that would be the dual motor which would give you 1000 watts. Which if I plug in a "big guy" number like 100kg and the extra weight of the scooter with bigger battery and extra motor I get this:

So like I've been saying to people, if your bigger (and or you want to hustle up more hills) then the dual motor version is the one to shoot for, but for me the single is entirely adequate.

Remember, they're both speed limited (in Australia its 24km/h), so that above result will see you going up hills better too.

Perhaps when I upgrade the battery pack from 8.8Ah (not planned any time soon, but probably inevitable knowing me) to have more Ah capacity I'll be more enthusiastic about using it on Unrestricted Power Mode.

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