I have been working on a 4 wheel drive electric skateboard for some time now. Let me share a bit about where I’m at with my project.
#1: For me the most important concept in Reliability is this: Your Motors come with “Maximum Specifications” such as Max amps. Also, your Vesc will have “Maximum Settings” for many parameters.
Do Not ever set your VESC to the Maximum Specifications for your Motor Wheels. I recommend trying everything at 77% to begin with. For example, if your Motor wheels are rated at 22 amps, try setting your vesc maximum motor current to 77% of 22 amps.
There is a rule in electronics that is something like government your self at least 15% capacity above what you will actually need. For Reliability in ESK8, go 20 to 23%. Then slowly adjust 1 parameters at a time up from there.
( * Some exceptions to this rule exist. Like for example, my motor wheels are rated for 12S, but I recently pared my 12S battery down to 11S for Reliability.
The point im trying to make is: Dont go in on the first day with the mind set that the 1st thing you want to do is make sure all of the advertised maximum specifications are correct to see what the true maximum power output can be like myself and everyone else does. Its hella expensive this way.
#2: The Documentation that comes with Vescs is usually minimal. However, I’d you go to the Website of the Original Vesc which was created by Benjamin Vedder, You will find Tutorials that basically define what the settings in the software are with more accuracy than almost any other source.
Be cautious because the original vescs are for 1 motor wheel only. You may or may not be using a Dual vesc. That Dual vesc may be using the same software for 2 motors, or may not. Just try to find some indication in the wording or try calling or emailig whoever’s you get your vescs from and ask then to recommend some safe starting parameters or some average start iij ng parameters. There recommendation may clarify if the setting is for 1 wheel or for each.
#3: As for your “Maximum Regenerative Braking Current”. Find out the maximum charging current for the specific type of battery in your pack. Now multiply that times the number of batteries in parallel. Now, MOST IMPORTANT THING TO REMEMBER, divide that number by 2 if you are using 4 wheel drive with 1 battery pack. Otherwise you will burn a small Integrated circuit on your Vescs PCB.
#4: There is not much “Linear Correspondance” between the Max ilk m UK m Amps specification of the Motors and the amount of amps being dr aw wn or delivered from the battery pack. This next thing I’m going to say is a rough example of what I mean, but is not technically correct.
" So You can set a limit to how much current your battery pack is allowed to supply. And You can set a limit to how much current your vesc can allow to go to your wheels. Also, there is a Duty Cycle modulation which can be imagined as a square wave with variable time for each pulse thus delivering more or less power per second.
So basically, when you start to accelerate on esk8 board, my very rough understanding is that the battery pack allows current to flow out of the battery pack while the duty cycle is at about 10 percent. Once the Battery Pack Amp limit is reached, then the amperage continues to increase until the Limit set for the Motor Wheels is reached. ( (Or Visa-versa depending on which l I’ll kit is reached first.) Only then does the duty cycle start to go up from 10% to a maximum of 95%.
So the point is that that didnt make that much sense in a “Linear” type of conceptual theory. It has to do with 3 phase not drawing power 100% of the time, some power reverberating in the motor coils, etc.
The point is that almost none really truly can explain in simple terms the way a vesc works. If you figure that out, I’d love to know.
#5: You do not need to oversize your Conduits in your battery pack. Just use several pure nickel strips between each battery at first and you’ll probably be fine.
Definitely use a spot welder. If you have access to 220VAC, buy one of the 220VAC Source Power Spot welders. It will be a lot stronger. It will probably cost a few hundred bucks, but it’s the only good way to do it.
Weight is important, fewer batteries mean lower weight. Less overkill on the connections between batteries can mean less weight. A overly heavy board is kind of lame.my board is way heavy because I overkolled my battery pack with lead and copper on top of the nickel strip. By the way, JB Weld can come in handy on the battery pack.
Also, the best way I’ve found to solder us with a phosphoric acid flux. And 50%lead/50%tin solid core solder. Rosin Core is garbage. Just get a bottle of Rust Remover Gel from your local hardware store. Make sure it has phosphoric acid as an ingredient. This shit works miracles. After words, sprinkle some baking soda on your soldered jo I’ll nta and rinse off with water then dry.
Other than that, you can use “butt connectors” to connect your parts together to test them the first time around. Tou dont need to make every wire connection bullet proof like old iron sides. If you use a butt connector and some electric tape, worst thing that can happen is a practically insignificant increase in resistance.
And btw, you dont need to connect the sensor ribbon cables for you electric skateboard to work. It just wont be quite as smooth from 0 to like 3 miles per hour. But it will still work.
You could set it up without the sensor wires the first time around or if your in a rush to get something working at the end of the semester etc.
Other than that, Have a Good Time; )
