@onloop I have to disagree with some of your points. I don’t mean this to shoot your points down but I think a lot of them really depend on perspective.
On the pros:
Hobby stuff has been dead easy. No custom firmware installs, no VMs, little to no troubleshooting for my motors
There are lots of boards running on loads of ESCs … there is more experience in the community on running hobby stuff. This custom stuff is new, not tried and tested (except by a privileged few) and I think how terrible I found Alien stuff to be for my circumstances (very hilly area) is testament to such issues.
See 2 … eventually but not initially
For 2 years I’ve been promised a replacement/upgrade from APS/Bruno. This has everything to do with suppliers and little to do with product. I had no problem sending back a defective Hobbyking (yes HK not HW) ESC.
Economies of scale rarely exist in hobbyist/custom products. Just as you hit it, the market saturates because it’s rather niche.
This is a true area advantage … purpose built.
I have no problem with 6S because I already have a boatload of torque … I want a skateboard not a weapon. Speed demons will disagree.
Your battery back is way too big and heavy for me … my new VESC (should they ever come) should be a little bit smaller than my existing trimmed down HK150A ESCs.
Unlikely … I print nice 3D printed enclosures for my gear that looks better than anything I can get on the market. I also quite like some of the HK/HW enclosures on Thingiverse and the like - I think they look far better than the discrete box styling of yours and other custom gear.
Eventually isn’t a pro until it happens. Hobby stuff is plug and play. I bought ESC, batteries and motors for my first board and was going without lifting a soldering iron.
On your cons:
I bought two new VESCs from your because two new HK ESCs come with way less features for nearly the same price. I think you’re already competitive on this particular point.
@onloop 2 Years on the same 6S budget ESC … that is pretty good reliability and only brought to an end by some rushed soldering. You are right that less Amps reduces a pile of issues but 10S is the point at which the Voltage also becomes risky such that at one of my workplaces my skateboard would not be allowed on premises without being sparky certified (above 36V).
So, are you saying VESC is going to struggle with the Amps on 6S? 1.5KW sustained seems fine to me (50A * 4.2V * 6cells). I think the C rating of cells is the bigger issue.
I have been trying to get my head around this statement for a while now. I just can’t see how a higher voltage could possibly lower peak Current.
edit: wait I just got it. You need to change the motor!
here I am trying to do mathematical equations at 4am and I was working with the same load!
in order to lower the current you need to raise the load (ie change to a different motor) I was trying to work it out based on just adding a bigger battery to the existing motor. (it doesn’t work. in fact it does the opposite)
Well i was not really referring to the VESC, I was just saying in general that higher voltage (10s or 12s) & lower current is better on an eboard.
however in relation to the VESC, it is actually more efficient to use higher voltage. The VESC was designed with components that support up to 60V, these components & VESC work better with higher voltage.
If you are going with 6S on VESC you should change the MOSFETS to the lower voltage ones as they have lower resistance. Also, the parts are slightly cheaper if you build a VESC for max 40V
I did consider building with 6S as i could build cheaper eboards, but in the long run i want maximum efficient, low current, low heat… this way i can build better eboards.
Higher voltage increases motor RPM, so you will need to change the gearing ratio to keep the top speed the same, more reduction!. Or just get a motor with a lower KV.
Well there is no chance of different MOSFETs now as I already ordered my VESCs a month ago. Just waiting desperately on the promised 1st week of October delivery so I can get riding again. As you raise the point of 10S and gearing this is another reason I wouldn’t use 10S. I can’t go any smaller on my motor pulley. There is not much room to go too much bigger on my wheel pulley plus I really don’t want to go through other the expense to buy or the time to CNC up another set and I’m about as low as we can go with KV. So these late VESCs better be worth the wait.
Yeah. It is worth noting that if you just up the battery and DO NOT change the load (i.e. motor or gearing) you will INCREASE the current.
so if your plan is to go 10S battery to reduce Amps but not increasing your load by changing the motor, you will do the opposite! Peak Amps will be Higher.
(thats where I was confusing myself the other day)
@onloop, it’s always great to wait two weeks longer than promised at no extra charge.
@lowGuido, You are missing a piece of the puzzle in your thinking. If you increase your voltage (i.e. go 10S) but keep the same load on a simple fixed load (resistance) circuit then the current would increase as per V=IR. But a motor/ESC is not a fixed load … it’s variable and you vary it to do a certain amount of work i.e. pushing us along happily at 30km/h. To do the same instantaneous work you need the same power … power is the result of current x voltage (P=IV). In other words as the voltage goes up the current comes down for the same power output. Did that makes sense?
Just to add to the discussion - I presume in a case like this, it would be the duty cycle changing (lower duty cycle for a higher V, everything else equal). @roller did indicate a particular power output in the context of achieving a given speed. Sure, power output over time isn’t constant for either system, but to attain the same speed (or kinetic energy produced by the work done), the power output of the motors should be the same, assuming ideal components and all that. There are certainly second order electronic issues, at least, that complicate things.
Of course, it is correct that the peak current in the higher-V system is larger, but the power output, and hence speed, is also higher. Like you said, though, onloop did say peak.
He also said
I know what he meant by that, but just to clarify things in my own mind: From what I’ve read on Vedder’s site, my understanding is that these numbers would actually be the battery current, due to a less-than-100% duty cycle in the motors (to achieve the same 1000W - the 10S could push more). Whereas, the motors receive the full I = V/R current for the portions of the duty cycle they are being powered. Does this sound right?
@emotiva I was trying to keep it simple to explain to @lowGuido the current would be lower not higher in at least half the circuit… as you say into the ESC. Coming out of the ESC is a pulse and really that is much more complicated to break down. The main point is that you can’t simplify it to a V=IR or that plain amps really as much at that point.
@onloop Only just saw your message about sending out early, LOL. Thanks for trying but semester is over now anyway so I am just waiting for the one you wanted to release. How much longer before the October batch gets sent??
the point I was trying to make with this article is if you buy the cheapest of everything you might NOT end up with a high-quality build… it could fail and you might need to replace parts. therefore not saving much money.
I think it’s a valid point…
the first build i made i was on a VERY TIGHT budget… i bought the cheapest stuff i could find. Did it save me money in the long run? NO!!, because things broke. chargers didn’t work, batteries swelled up, ESC’s failed…
the beauty of DIY is it’s up to you! you can ignore my advice and choose your own path… in fact i would prefer everyone buys the cheap stuff first and learns about building an eboard and increases their knowledge without so much coin on the table…
people learn much more from their own mistakes… I simply tried to articulate what i learned from making the mistakes i made…
There is a point to how cheap you can purchase. You can most definitely purchase off the shelf for most items and you don’t need to buy anything but the motor mounts, escs.
Not everything is worth spending high dollar value.
My first board ran like a champ and is still running with no issues of failing. RC Lipos, SK3 motors from HobbyKing and of course I’ve switched out the ESCs here and there but motors tend to last forever unless you cut or ruin the wires and/or magnets fall off but that’s slim to none even with hobby king motors. I find them highly reliable.
Want a cheap setup… more then enough people have tried a single motor on 6S battery + 230-245kv for 20mph. Can’t go wrong and if anything messes up you can replace it. If you want throw in a VESC and you can upgrade to a 12S.
I’m with you right there