Noob question thread! 2020_Summer

howcome? Can you explain in laymans, I don’t have the smart=z :expressionless:

what’s the DRV chip do and what does it mean for it to be a 60V DRV? What are the implications of that on a 13s?

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found this on endless sphere

“3: Input voltage recommended for FOCBOX is 50.4 maximum, your is 57 which is high.”
My battery can only produce a max of 42v, thus it is impossible to exceed 50.4v since 42v is less than 50.4v. I have a 10s4p battery pack, so 42v max, 60A max since I am using Samsung 30Q cells.

The voltage they’re stating is recorded on the unit, it did happen. There are a variety of ways to get to bus voltage that high, it’s normal to see voltage spikes with large phase amps and inadequate capacitance. Alternatively if you took the board past its geared maximum RPM down a big hill this would also blow it up pretty rapidly. Why did you have the erpm set so high?

large phase amps can get voltage spikes in a focbox? what’s that about?

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hmm it’s interesting the Unity can’t handle 13s but dual focbox can?

If I have a 3.5kw motors and 10s battery dual focboxes. can I push my motor amps to 3.5k2/42v/0.95duty = 87amps? is that the limit baring heat? currently at 70A.

is the limit just heat? what gives a motor it’s watt rating?

FOCBOX max is 50.4V
FOCBOX Unity max is 50.4V

Anything with a DRV8301 or DRV8302 is max 50.4V


The limit is heat but I think if you try to drive too much current you can get cogging from oversaturation but I’m not the expert on that. Try reading somewhere in here

Also the rating is just a rough guide. Empirical data is king.

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so wait, howcome all those fuckers testing neoboxes on 13s are having no problems if it’s a direct focbox clone? Or doe it have an upgrzded DRV?

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A fully charged 13S is 54.6V so still within the 60V limits of the DRV.
It is awfully close to the limit, and voltage spikes will most likely exceed 60V and cause the chip to blow.


All have a real maximum of 60V, but because when you switch it on, when you hit the brakes and I think also when you switch it off, spikes happen, which increase the voltage. So, unless you like to blow up your VESC in the worst possible moment (trying to emergency brake), you need a safety margin. I would not exceed 52.5V = 12.5s. The next closest series connection possible is 12s = 50.4v (unless you happen to know where to get half batteries :joy:).
At 13s = 54.6V you are asking for problems.


By this logic you should red line your vauxhall corsa just because the corsa next to you is slightly faster.
I mean it will work, but eventually something bad will happen that wouldn’t have happened if you were within the recommended limits.
If you have exceptionally bad luck you won’t get to the first corner


I think started to always skipping originally after 6-7km ride. Though trying to fix it, next ride after a km or so it just came loose/skipped on hard braking. Tried again, belt loose after 1-2 km again, figured out motor pulleys are loose. tried fixing it again, after 3 km seems solid now.

Weird think is I reapplied loctite to motor screws last time, but it came loose still. But at that time motor pulley was also loose. Belt came loose after 1-2km. Retightened belt and motor, also repapplied loctite to motor pulley, yet it seems fine now.

There is a clicking noise sometimes though. Worried that motor pulleys will come loose again, though I don’t think it’s possible for them to fall off besides when a belt snaps if they come loose again.

Search for a component/part number and “datasheet” and usually can find datasheet from the mfg that specifies all the hard limits in terms of max voltage and current and usually there is a peak vs sustained value for the current based on how quickly the component will dissipate heat. The drv is mosfet driver chip and is made of conductors and semiconductors separated by very small fractions of a millimeter (CPUs are nanoscale at like 14nm between anode and cathode of transistors made with photolithography techniques), long story short they design and test them with certain limits and then publish specs for safe operation. Generally rule of thumb is leave 20% error or make sure components are only at 80% max capacity to avoid having small surges cause issues.

The MOSFET driver chip has a linear voltage regulator (thing that steps down the input voltage) built into it for other integrated circuits (ICs) and it essentially has fast firing switches that it can use to open and close the MOSFETs (think of them as just higher load switches), so have your low power/current switches that run fast on the DRV that are meant to drive the bigger switches/gates (MOSFETs) to control the rate of current flow into a given coil at a given moment. It’s up to the ESC to determine the RPM of the rotating magnetic field it’s creating and attempt to determine the correct 0 point crossing. There is another integrated circuit on the VESC that is very important that is the STM32 chip which is an MCU or basically a simple computer on a single chip so it has it’s own static memory (like a hard drive but is flash memory) and has it’s own working memory (RAM essentially) and a CPU for processing instructions. When you “program the vesc” or “write configuration” using the vesc tool you are updating the flash memory in that chip and the VESC firmware that is reading control input is running on that CPU and reading/decoding the control input signal and looking at config data to determine what signals to send over to the DRV to drive the motor.


The actual max voltage listed for either the 8301 or 8302 is 65V, the recommend max is 60V, going with the higher number 65V if we take 80% of that it’s 52V. Could we use that extra 20% of “overhead”, yes but as others said there are dips and spikes in the voltage as current begins or stops flowing between things so up to you if that risk is worth it but if looking to build a reliable ride that you use year round I wouldn’t recommend this. Another issue is the 60k erpm limit with the 4.x design which keeping your voltage in the lower range just means you can go higher with the kv before you hit the erpm limit (people who don’t know what’s what yet are less likely to blow things sticking with 10S or below basically when we don’t know which particular VESC they have)


What kind of bolts/screws are you using? Ideally you should be using high strength (class 10.9 or 12.9) fasteners.

Also did you A: Clean and degrease before applying loctite and B: Let the loctite cure for the recommended amount of time?


@wafflejock thanks a shit ton for the knowledge!! About 74% of it was digestible for me, which illuminaed many things! I’ve seen things like DRV and STM32 thrown around and never knew what they were, now I have a better understanding of what people are talking about! Thanks again dude

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sorry if this dropped in your thread @whaddys and appeared to be related. I was trying to ask a totally separate question about what causes voltage spikes above battery voltage.

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whys my board so slow? k so i bought an apsuboard x1 with 270kv 5045 motors, 10s, hobbywing esc. i put the china 6x2 air tires on it with 60t/13t gears and it would do about 25mph and climb hills OK. i decided i wanted better climbing along with a more reasonable belt setup because with the 60/13 the belt was only engaging 2 teeth on the motor gear. so i got a pair of flipsky 190kv 6354 motors, an mboards dual belt drive esc, and switched to 42t/13t pulleys. im running sensorless because the motor and esc dont have the same type of sensor connectors. the board is SLOW. like, 20mph and will NOT climb a hill anything like it would before. what have i done wrong? according to the calculator the speed should be about the same with the lower Kv and longer gearing. also the controls are horrifically unresponsive. like i almost get thrown off the board because the throttle and brake are so delayed and i cant anticipate it. as far as i understand from what ive read, when running sensorless, the three motor wires can be plugged in in any order, right? i switched them around so theyre going the right direction and thats it. i cant find any documentation on how to actually program this esc but it does have a button on it that i assume is used for that. i did confirm that they did sent me the 10s version like i ordered so no problem there. maybe they sent me the hub motor version instead of the belt drive version? not sure how to tell. i appreciate any help yall can give me.

maybe because you bought a shit product from an absolute shit “vendor”

You got this i assume?

oh and welcome to the best forum btw.


this is the problem.

iirc the Lingyi esc won’t do more than 10 or 15A per side for motors, and also there is a speed limiter, but i don’t recall what was the speed they are set to.

and mboards actually delivers? thats new