Sunday 28 June 2020

help me choose a scooter

One of the most common questions is:
Help my choose a scooter

Really there's so much personal in that but if you strip away your own desires for how it looks and focus on what you need of it (performance) then you can set yourself up pretty well for dismissing lots, leaving more time to enjoying life on your scooter (rather than fussing about what to buy with no actual criteria to help you).

I wanted something which could fold and fit in my car, not break my back putting it there and climb the hills around where I lived. I ended up with this


So what you want it to look like aside, to me the best you can hope for is to use your own understandings of physics and make some educated guesses based on specs.  Weight of the scoot is pretty straighforward, but what's often difficult is "range and speed" (and often forgotten is hill climbing).

For instance its well understood what energy is needed to get a human body up a hill on a 2 wheeled machine, cyclists have been into this for decades and there are good online calculators: I've used this one. Those are actually my parameters and have proven very consistent in estimating my scooters (all of them). About a year back I put this blog post together to understand my scooter (then the 500W Mercane single motor) and then estimate if the 1000W dual motor (otherwise the same as the single) would give me better hill climbing (speeds on the flat were essentially firmware limited to comply with the law) and be worth my while buying.

For instance in my parameters above I picked 8% because that's not steep:
... Maximum slope for hand-propelled wheelchair ramps should 4.8 degree angle or 8.3% grade. Maximum slope for power chairs should be 7.1 degree angle; 12.5% grade.

my driveway is more than twice that and so is the top of my street. So I needed more and so plugged in higher numbers into that calculator above and it was pretty clear what I needed.

Plug in your own weight and see what you should need in terms of battery capacity even for just "regular riding" (meaning not climbing steep hills if you don't have them). You'll also see that as you go faster (even on a flat) more power is needed, its not a linear relationship (meaning that to go twice as fast you need a LOT more than twice the power). Power is best measured in Watts (unless you ride horses ... then I suppose Horse Power makes some sense).

Next you'll put that requirement (of power) into a simple calculation of how many Watt hours (its simple because if you use 400Watts to maintain a speed for an hour you'll need 400 Watt hours (Wh). The faster you want to go the more Wh you'll use (even per distance) because physics is a harsh mistress, you can dream any wanking you like, but she won't let you live it out.

My Mercane Widewheel cost AU$1400 weighs 24kg and has a 633Wh battery. However the reality is you can't get more than 70% out of a battery (without probably walking) and you probably shouldn't run it that flat often anway. So that means a usable Wh from my battery 450Wh ... which I don't usually push it that deeply (but go close).

That'll allow me to do this, and learn from that to make this estimate of 1.96kWh / 100km  As well as informing me about how to make further decisions. 

So from this you should now be able to make some informed decisions about what power you need and how much battery capacity you need for that task (and your range).

In contrast my Mercane MX60 has a 1200Wh battery (which for a reality check is not far from the size used in a Hybrid Car), the scooter cost me AU$3000 and gives a usable range of 30km (probably more if I was willing to risk having to push it and go slower). But at 34kg its bloody heavy to lift and I seldom take it anywhere in the car (and thank Gawd that my house is low set or it wouldn't even be an option), which I indeed do with the Widewheel. I mainly use it on the weekends now as I actually don't like the fact that its so much higher than the widewheel, even if it cruises bumpy roads better.

So everything is a trade off, if you want more power you'll have a bigger thing (kids today probably don't work on engines of cars anymore and so this is perhaps not obvious):


If you want to go faster you'll need:
  • more power
  • bigger battery (to deliver more power and longer if you want any range)
  • better suspension
  • better wheels
  • stronger chassis
  • good steering dynamics (better read this, scooter folks seem ignorant of this point)
and that will cost you more money and a penalty of greater weight (because physics is a harsh mistress).

Next we come to the old chestnut of tyres; I was 100% clear (after many years of bicycles and motorcycles) that I did not want pneumatic tyres on my scooter for work commuting. Flats are inevitable and and more pronounced with smaller wheels and much harder to fix with smaller wheels.


I subsequently bought a scooter as a "fun thing" which did have pneumatic tyres (the MX60 above) and in less time I've changed more tyres and had more struggle with that than the entire amount of time spent on the Widewheel.




think about that...

Thus we come back to the beginning where I suggested "focus on what you need of it" not the wanking of how it looks in pictures. Ask yourself:
  • will I need to carry it (or push it)
  • do I need the range (if yes perhaps look carefully at an eBike or (gosh) a motorbike)
  • how much am I willing to spend (as much as a motorcycle)?
Lastly (hopefully you read the other ones), I recommend you read these two about scoots and reality, and then read this post for thoughts. It will perhaps help you to understand your needs and see the experiences of somone who has probably used a bigger variety of 2 wheeled transport for quite some time.

Teach a Man to Fish ... Time for a beer I say, and I know which scoot it'll be that I take ;-)


Happy Scooting

Sunday 21 June 2020

the permatex question (perhaps answered for good?)

The problem with the covers of the Mercane Wide Wheel is that the covers for the suspension are crap plastic and break (often come broken) at where they attach. This is one of mine which you can see is pretty new but just broke as soon as I started to screw it in


Indeed looking at the striated marks in the plastic I wonder about the production. However the other parts of the plastic are strong enough, its just the critical part where they attach. See my page on a repair option here.

Its increasingly said on Reddit (which seems to be the online instrument of the Zombies of Morinity) that somehow relatively benign thread lockers (essential for good scooter life in operation) are somehow damaging the plastics. Statements like this crop up with out any validation:
Just realized that blue loctite causes the suspension covers on the WideWheel pro covers to crack.
and seemingly nobody does anything more than read the headline to take the claim unchallenged. But I guess this is "normal" in a BLM (Blank minded Looting Mayhem) world.

So while a bit of internet searching found this interesting post (which it would seem again, people only read the headline, but not the substance). In that post (claiming that permatex caused fractures in his 3D prints) there were some intelligent questions (which went unanswered), such as: "I can’t speak to ABS, but we’ve used Loctite dozens of times with screws in tapped polycarbonate without any issues. Perhaps the specific kind of Loctite or polycarbonate you’re using is more susceptible to problems?"

There were (in the comments) mentions of Acetone, being one trained in Organic Chemistry I know well the smell of Acetone, I can't smell any in Permatex Blue. Further acetone is regularly used as a glue for ABS plastics ... so that's weird too.

So as exactly this sort of fracturing happened to me straight out of the box on my Widewheel without even any Permatex ever coming near it, and again on half the ones I bought new I'm going to say that the low hanging fruit here is: crappy molding which let the plastic get cold and  become  brittle. I notice its not a problem anywhere else on those covers (wheel or base).

Futher discussion without any testing is just meaningless, so I decided to do some testing to answer the question with the product I use (which is Permatex Blue). So this is the video of the start of the experiment:


and this is the conclusion:


My findings were that I can't see anything obvious that would implicate permatex blue thread locker as having any obvious effect on the plastic. Given that people claim this happens instantly and I let it sit there for 24 hours, with drops of permatex on it, not just the vapors suggests this claim is false.

I didn't test the loctite brand.

Further I've used Permatex Blue on my both my scooters and on my friends three (himself plus his two daughters) for a year now with no evidence that this claim has any substance.

So if your covers break at the mount points its either (or a combination) of these:

  1. crap plastic from the start
  2. you overtightened it ... so use permatex.
Now if you're unconvinced (some people still believe Donald Dumps claims of COVID) then I suggest you remove all the metal screws ther and replace them with Nylon ones (which can be easily trimmed to the right length). They are M3, but see my above mentioned blog post for details. They probably won't vibrate out and won't rust in there. 

If you're going with the OEM metal ones, please, put a drop of permatex on there when inserting the screws (just a drop) and you'll have no rust problems and they won't fall out. I've not needed to open the bottom of my dualie since doing initial inspections.

Lastly, if in doubt, do your own test (with your own choice of thread locker) and see. Science and Engineering built the world we have today by validation and verification, not finger pointing and did / did not / did too circular arguments with no substance. Unless you're a narcissist prone to magical thinking with no concept of reality except it to be what you want it to be (like Donald Dump).

Happy Scooting



Monday 15 June 2020

MX60 - the Korean site

Not sure how many people see this site, but ... well here it is: https://www.mercane.co.kr/copy-of-widewheel-kor

well worth a look, even if you can't read Korean (mine was never that good), its worth looking at for just the specs


Saturday 13 June 2020

afternoon of dirt roads

Well after a week cooped up all daylight hours (well, more or less) in the house (working from home), its nice to go out for a ride on the scooter around the countryside where I live. Well after having done the shopping (by motorbike) and the usual stuff around the house (washing, chopping some wood) I can go out for a little scoot.


Fortunately its quite dry here at the moment.

So I took the MX60 out for a longer run and did about 30km


and from leaving home to getting home (including taking some pictures, bumping into a mate out on the tracks on his dirt bike and having a yak with another mate at the servo) I took about an hour.

I didn't use the GPS, but looking down at my speedo I was doing 24kmh in rougher places and 35kmh in nicer places (and down hills) and hit a max of about 51kmh on the steep downhill back into town.

There were some long steep uphills like this:



and some nice gentle rolling countryside (although quite a many corrugations which you need to pick your lines around to avoid them)


I returned with 30% showing on the battery indicator (no, not the dash one, which just shows volts). So assuming that it is correct it'll require 840Wh to recharge having done 30km. So thats 35km/kWh or 2.8kWh per 100km which is more than my Widewheel at 1.96kWh/100km but then its going faster over rougher roads.

All up a nice afternoon out on the MX60 doing stuff that the Widewheel couldn't but a dirtbike would do perhaps better but somehow I prefer the scooter

:-)

Friday 5 June 2020

Fixing Ozito X 18V lithium batteries

There is a system of rechargable battery tools sold in (at least) Australia (by Bunnings) which I happen to have a few of in different sizes.


Yesterday I went to use this one, which I hadn't used for a good 6 months, and pressing the button for power showed me that only on dot was blinking, so before grabbing another one, I put it on the charger only to get the red and green flashing - alerting me to a failure to charge.

I wondered what the problem could be so I took it apart. Having never done one of these (but have rebuilt a few older Ryobi NiMH battery packs) I started by undoing the screws here:


which uses a #10 Torx driver.

The bottom stays attached and has some lugs (inside) that keep the base snapped on even without the screws (don't count on that) and I needed to prise it off starting at the front  (pulling apart with my hands at first then fitting in a wide flat blade screwdriver working around left to right.


When the base comes off beware of the spring that us under the battery relase button and the small bit of plastic that is underneath what you press when you check the voltage.

Now I didn't know what to expect, but when I pulled it apart I found it was all pretty clean, no tabs broken off, corroded or anything obvious so I decided to then just measure the batteries.


A quick measurement with my meter showed that one cell was down (out of 5) and while the other 4 were perfect (4.13V) that one was 3.9 ... now I know that it has a Battery Management System (BMS) and I know that the role of a BMS is to charge the pack in a balanced manner, but I also know that some BMS do not cope if one cell (or group in parallel arrangements) is down too far below the others.  Some only cope with 0.2V. (Note you can see the spring I mentioned above at the back there).

So I hooked up my iMAX charger and charged that cell up


which took some time actually, so either its been getting slowly out of balance for a while or the BMS has a fault ... I'll find out eventually. Worth observing here is that all those spot welds are impeccable, among the best I've seen anywhere.

Either way I was able to put it onto the charger (as it was) and confirmed it was then charging fine, put it back together and tested it last night with the blower (yes I'm evil).

Hopefully Win Win.

So if you have some Bunnings Ozito packs which may not have been used for a while, and won't charge, its worth having a go at this yourself. You'll need:

  • a lithium battery charger (worth having if you have a number of things with lithium cells, scooter, skateboard, laptop ...
  • a multi-meter (even a $20 one)
  • some basic tools
Hope that helps