This is just kind of a thing I wanted to attempt for a friend, so the budget is not very high. The biggest hold back for me is the frame/chassis. I donāt mind fabricating things like motor mounts and adapting various parts, batteries/escs are no problem for me either, I just didnāt know if thereās a place to get rolling chassis for electric scooters as I donāt really feel like fabricating an entire frame. Way out of my time/patience.
I think @Riako has a vast knowledge on this. He has built an e scooter for his wife i do beleive?
2 Likes
So say I wanted to turn down the ends of a caliber truck to a cylindrical profile for a bearing to seat onā¦
Is this wise? How would I go about doing it given my complete lack of actual power tools?
For context it would just be a cm or so off the ends.
Other then battery size/ cell type and type of wheels how are some other ways to increase the range of a board in the build process?
In particular gearing and motor selection.
Say i didnt want a big top speed, 35km/h or somwhere there would it be better to go to a low gear ratio? so theres less power used to get up to sleep.
Also motor selection, if you can get your desired speed from duel 50xx motors is that more efficient then duel 63xx motors? Or do the bigger motors do the same job just more efficiently.
What Iāve always stuck to is the motor is most efficient running at about 80-90% of itās max RPM based on voltage/kV. Running higher battery voltage for higher motor speeds, then gearing it down so that top speed is just a little more than your ideal cruising speed. 50xx might be marginally more efficient if youāre not pushing the stator towards saturation.
Although thereās another thread discussing inefficiencies from too high RPMs and what I said are just general rule of thumbs, true for most setups but not all.
2 Likes
A cm or two on the end shouldnāt affect the strength very much.
However turning a reasonably precise square and cylindrical bearing seat with no proper tools is pretty much impossible. Iād say take it to a local machinist and have them do it. Itās a simple operation with the proper tools (a lathe), and they shouldnāt charge too much. Iād say youād probably spend a similar amount on a new truck after you screw up the original trying to do it by hand.
2 Likes
Using lower belt tension (idlers) reduces friction losses there. (slightly)
Higher durometer wheels have less rolling resistance. (slightly)
Air resistance increases by the cube of your speed, so slowing down a little bit helps your range a lot.
FOC is more efficient than BLDC. (slightly)
Motors generally have internal losses proportional to size (larger motor, more losses), but conversely the harder you load them down, the lower their efficiency gets (smaller motor same load, more losses), so thereās some contradiction there.
Honestly our drivetrains are pretty dang efficient overall (probably better than 75-80% all up), so chasing small incremental gains there isnāt gonna give you a massive reward. The two huge factors are how much energy you have (battery size), and your cruising speed (wind resistance), which is the main source of power consumption. Everything else is small potatoes in comparison.
This isnāt like gas guzzlers where the engines waste 75% of the energy in the fuel, and the transmission wastes another 15-30% of whatās left, where a 3% improvement somewhere can give you a significant overall mpg increase.
4 Likes
What is latest Unity firmware? Iām on 23.46
Donāt know why that replied to you, but Iāll leave it uhhhā¦ Like that.
3 Likes
So Iāll fairly soon will be getting my deck with a carbon fibre bottom and Iāve understod itās necessary to use fishpaper to avoid reciever signal failures as well as to avoid shorting anything (CF=conductive).
Iād prefer to mount everthing to the deck instead of the enclosure so Iāve got two questions:
- Should I just put down a layer (how thick?) between the all the components and the deck?
- Iāll be using a Unity with a mounting plate (https://electricboardsolutions.com/collections/speed-controller/products/focbox-unity-mounting-plate). I wanted initially to mount this to the deck itself but the screws would go through the CF in that case (chance to short something in the ESC)? Should I just mount it to the enclosure instead or is there an safe way to mount it to the deck?
This is my first build, be gentle! Cheers fellas
1 Like
-
Fish paper is not going to help with any receiver signal issues that the carbon fibre may cause, it is really just for use as an insulator and is quite resistant to abrasion. Any is better than none, I donāt think thickness is a huge deal here.
-
Use adhesive backed velcro to attach the unity to the deck and some sort of adhesive foam on the inside of the enclosure to support the unity from coming unstuck due to vibration.
2 Likes
Thanks man! Nr 2 seems like a solid solution. I think Iāll do something similiar for the remote reciever as well.
Kudos!
1 Like
No dramas mate. Velcro and foam can take up quite a bit of height in the enclosure, if you are tight for space you could substitute the velcro for double sided tape, but it wonāt be as easy to remove.
1 Like
Given the same drive train setup and a max speed of 40kph (ie. not looking to increase top speed) is there any difference between using the following batteries?
6s4p
8s3p
12s2p
would there be any range differences?
I guess my main point is that if I want the most range would it be better to put high capacity, lower discharge cells in with more p or more s?
Yes there would be differences.
Cheers man, Iāll keep an eye out for clearance
increasing gear ratio, lowering the motor current, and having lower resistance motors and smaller wheels are generally ways to increase range.
1 Like
q. why wouldnāt you use NESE over spot-welded battery? if thereās a dud cell itās more easily fixable with NESE, if you want modular battery to fly with then go with NESE, if you want a cheaper option, go with NESEā¦what exactly is the downside other than maybe a bit more bulk?
I agree, it is superior in almost every wayā¦ except weight and volume. So if that matters (and it almost always does) you have to look at the tradeoff.
E.g. I would like to fit a nice battery inside my B&W outdoor case (~200x150x80mm) and it just wouldnāt work with NESE. So I need to either use a much more bulky case or use a traditional battery pack.
1 Like