I am completely new to the world of DIY eskates and I am looking into creating my first board.
I have two flipsky 5048 motors which I am looking to power with a 10s2p Lipo set of turnigy 5000Ah 20-40C, which makes it a 10Ah 37V pack. Typically the flipsky dual VESCs that I find are up to 300A burst, so I guess my main question is: theoretically my battery setup can give a peak of 400A which would damage the VESc, right? So do you think I should play safe and use a 20-30C battery pack instead?
I have read in the forum that the C ratings tend to be overestimated so maybe I am ok even with a 20-40C, but I am still a bit concerned. Although I am leaning more towards range instead of pure performance, given that I have no experience, I am concerned that maybe 20C-30C will not have enough punch?
Thank you very much!
Hi!
Your rule of thumb is battery max > esc max amperage. But, since you’re free to configure esc parameters, you can set your esc’s battery current to the minimum of battery max and esc max. Esc won’t pull more than that => won’t fry itself.
Don’t forget that you should double the esc setting, because in case first esc pulls 40A max, second does the same. That is 80A battery current in total.
And I have to mention - do not rely on peak ratings too much, use continuous. Those ones are way more reliable
Hi kntzn thanks for the super fast reply!
Ah ok, so basically this means that I can safely use a 30-40C battery pack by setting the dual esc to never draw more than 300A even instantaneous.
From my understanding the 40C refers to the peak discharge that will not fry the battery (right?), whereas the 300A max burst rating of the ESC is the max instantaneous current that the ESC can handle without frying. But then why are the ESCs rated to a max amp burst if it is the year that defines how much you want the ESC to draw from the battery?
In my case if I set the esc to draw 100A continuous and a burst of no more than 250A (to be on the safe side), will be ok? Will I have good power while. It risking to fry the ESc which is rated to 300A?
Sorry for probably re-stating the obvious and asking noob questions but just need to make sure I have the fundamentals first before setting anything on fire!
Thanks again!
These motors are very small. Maybe they can do 30-40 phase amps? I have flipsky 6374 with a 10s battery and i am pushing 100 phase amps and 50 battery amps per motor. Are you from Greece by any chance?
Hi Dimo, yes from Greece. I got those 5048 motors because I am not going for max performance but they still seemed pretty strong at 1300W each (I got two). The max current according to the flipsky website is 36A.
Do you think these motors will be anemic or I am risking of burning them with the planned battery/esc setup?
The whole idea when I purchased them was that according my research those watts (2600 in total) seemed more than enough and I preferred having two on the board for better traction (instead of one 6374). But two 6374 would not fit in my calibre II trucks I think anyway…
This is phase amps not battery amps. I would get 6355 minimum but if you have 5048 try them and see how you like them. You don’t need a very powerful vesc for these motors. You need like 25 battery amps for each motor
Ok thank you! So the battery can theoretically safely flow 200A (20C*10Ah) to my dual VESC, but I set the VESC for example to 90A continuous (instead of its max continuous of 100A for safety), and then does this mean that eventually the motors are getting 45 phase amps each?
So in this scenario:
The battery will not be overheated as current is flowing from it (90A) is well below its max continuous of 200A, correct?
The dual VESC will not overheat as it is set to 90A (below its 100A continuous limit), correct?
But my -small low power- motors will overheat as they will be getting 45phase amps from the ESC, whereas according to flipsky stats their max current is 36A, correct?
Apologies for this long text, I am trying to deconfuse myself as all these are quite new to me and I want to learn.
Thanks everyone!
No meed to apologize, we love noobs here. Everyone has to start somewhere
Your statements are correct about battery amps - then esc amps - and motor amps being higher than the motors can take but there is more info you need
You battery is more than capable. So let’s go to the vesc
Your esc will take 2 separate amp settings, one for the left and one for the right. say 45a each for a total of 90a. This will be “battery amps “ in the vesc settings. This is a little high for the motors but not too crazy. You should keep an eye on the motor temps to see that you don’t overheat them.
There is another amperage setting, this is the motor amps. This setting generally applies to the low speed and starting from 0 amps. You will need to set this to something you’re motors can take as well and 45a each will work the same way for a total of 90a.
Battery amps are like your maximum battery draw and high speed (higher duty cycle) torque. Motor amps are low speed and lower duty cycle limits and will be the starting torque feel and amp draw wont necessarily be translated to the battery amps. I have a battery rated to 100a, and my total esc battery amps is set to 50a+50a - then my motors are good for 100a each and my esc is rated to 280a - my motor amp setting is at 100a (so the motor is fine) and total motor amps is 100+100 - so is less than my esc 280a rating and the esc is fine.
With those small motors, exceeding the rated amps will start to overheat them but it is something of a mushy limit - if you don’t ride super hard and give your motors time too cool they will happily take more amps (to a point)
Thank you very much Pecos and wonderful people of the forum!
So from what I understand, I have two options here:
A. Keep my small motors, and accept that despite my battery can provide lots of amperage (200A), I would have set my esc to pull around 72A battery amps (36A each motor) and set the motor amps to 36A each as well, if I want to be mathematically correct without going to the “mushy limit” Pecos mentioned
B. Get bigger motors (for instance 6355), which have max current of 65A. In this case I would pull say 50A + 50A battery amps (to maximise the ESC continuous capability), and set motor amps to 65A (so sending 65A to each motor).
Option A seems like a waste of battery and esc/resources, (while also being potentially weak?), while option B is a waste of only battery resources.
I could, but annoyingly they come with weird MT30 connector I know nothing about and can’t find adaptor… So I would have to do a cable surgery which ideally I don’t want to unless I am commited I want to stick with them
Sounds like you’re on the right track, now it comes down to budget and opinions. My opinion is if you stay with the small motors you’ll quickly grow out of them and want to replace them. 36a on vesc feels pretty weak to me BUT i live in the land of hills and vehicles exceeding the speed limits by 50% or more so i want to be faster to get off busy roads as soon as possible as well as zoom even up a 30% grade.
If your goal is a last mile commute board or something fun but smaller and more stealthy you will have a blast with 36a. Not every board has to be a rocket, with surf trucks and some nice wheels, 36a can be a lot of fun.
Do you have a board you want this build to feel like? What is your reference point for the performance you want?
Hi Pecos thanks for the info and sorry for the late reply, crazy day at work…
Actually the initial specifications I set were more towards range than speed/performance (as I am not a technical downhill rider anyway ), but still I consciously went for the 5048 as to “not overdo it with power” (2*5048 at the time seemed like too much power already). But looks like I was way off in my estimations…
What you and Dimos mention makes lot of sense actually. Although I am not planning to go super fast, it would be nice to have some extra power if required (I am not living in flat land and smooth roads too!). Maybe I can keep the small motors to build a spare cruiser with an old small 30” deck I have. The deck I am planning to use is around 34” and caliber II trucks which are reversed king pins, so theoretically can handle higher speeds.
I’ve always built (I mean I have built it once and re-made it 6 times) a single motor board and used 5065 motor. I was fine with my 1250w (~50a but 270kv) and 20 mph top speed.
After a couple of years messing with different non-esk8 engineering stuff I came back to esk8 and what do you think I’ve done first? Exactly, I’ve ordered two beefy 3500w 6374s.
It is always better to overpower something and then cut down it’s power using software than limit yourself by some imaginary limits and make underpowered system, that can not zoom-zoom even if you (i mean, when you will) want it to. That’s what I’ve learned it this 3-year gap.
Thanks for the feedback kntzn! Yeah, I am sold… I somehow managed to believe that 2*5048 was way much power… I didn’t know about what you mentioned (power reduction through software), so my concern was reduced range and too much power for me to handle… now thanks to all of you I know better!
Well, yeah initially it seems like is beefy motor will drain more so less range.
But it is all about physics: battery contains energy. You ride and have a drag forces (friction/air resistance). Energy = force*distance.
Big motors, double motors, chains and belts, your weight increases friction by tens pf percents, but not hundreds. So your key for range is bigger battery and optimised setup. But definitely not smaller motors.
Speaking of setup, your battery seems fine for commuting ranges from Wh perspective.
And also, as @dimos15 have already said, you can keep motors and swap them later. And also, as @Pecos said, feel free to answer literally any questions. Nobody here bites. Like, at all.
Thanks kntzn that indeed makes a lot of sense! I am pretty sure that when I start the build I will get plenty of new questions… (or I will get a new thread then)… for now I guess I just wanted to check that my battery/esc/motor setup is compatible and reasonable. So I believe this is covered so thanks a lot!
The only thing that still huddles me as why flipsky has those mt30 jacks when even their own vescs have no mt30 output or even sell an adapter!
What am I supposed to do with it? By default the mt30 is useless and have to cut it and perform a surgery…
You have two options here:
A: buy a pairing mt-30 connector and solder it to vesc
B: buy 6 pairs of bananas/bullet connectors, remove mt-30 and solder bullets to motor/vesc. 4-4.5mm is sufficient to carry 45a motor amps
Personally I would choose bullets, because I don’t like yellow connectors all over the place
Yes I agree option B makes more sense as I also don’t want to have a connector on the VESC (once I get bigger motors that come with bullets I would have to take it off anyway)…
In fact, I could use bigger bananas/bullets so that my VESC is ready for the bigger motors… what size would I need if I end up using 6374 motors?
Thanks!!
If your 6374 motor will drain 90A max, you will be fine with 4-5.5 mm, rated for 32/50A. That is because you have to do something really weird to continuously drain 30A+ for a long enough to melt the connection. There is no strict standard. Flipsky 6374 come with 4.5mm bananas, for example. These connectors are not a weak spot.
And also, max motor current flows through each wire/connection 2/3 of the time. So you can multiply amp rating by 1.5.
), but still I consciously went for the 5048 as to “not overdo it with power” (2*5048 at the time seemed like too much power already). But looks like I was way off in my estimations…
