There is no single answer as the data is so fuzzy, Im not surprised so many fail, esp the way you see ppl treat them.
Factors like putting them in tiny enclosures with no air rattling about and huge long supply cable not even cabled tied together are all factors that aren’t helping. Many people abuse these things.
Not to mention there seems to be a design flaw, the drv does seem to fail a lot and in a specific spot even at 10s. After studying the datasheet, i made an educated guess on what i think is causing some of the problems and added extra protection on and off chip, as have some of those manufacturing vescs.
Someone really needs to sit down with it with an oscilloscope and do some extensive testing to give you a more definitive answer.
As for 13s, that really is too close to the drv limit, as b264 stated above, you need to leave some breathing room, esp as the stock caps are all 63v and under.
So between 10s and 12s, the heat is largely the same on the motors with it slightly higher on the wires for 10s due to the higher amp draw from a lower voltage pack? Trying not to get lost in the technical stuff lol
If that was the case wouldnt getting thicker wires mitigate the heat?
My dog is 4 legged, so it’s my cat. My cat is a dog, following your statement.
Back to topic, I don’t recall blown DRV VESCs since the 6x generation. Have you? I’m not saying it is absolutely safe. Just stating that use and feedback so far show we finally have something strong enough to not fail upon use at high voltage.
Look here is the truth. It doesn’t matter the series count. Over 13s you will kill escs no matter what
I think the real problem is people’s builds
vibration dampening
good soldering
good covered connections
good dust proofing
not taping or hot gluing pinned connections in place
using antispark switches with the wrong type of fets so when it fails it doesn’t backflow to battery and the ESC blows
having a shitty power connection or your board is off, remote is on and you are rolling fast enough to generate bemf to power on the controller, it brakes and there’s no where for the current to go and it pops.
I think most Focbox failures are related to all the above which is basically user error.
Basically the margin for user error is high on any voltage… lol
@Jmding I think the benefit of 12S you are pointing out is this…
Suppose I am willing to accept 10S performance from a 12S battery upgrade, in other words 10S top speed and acceleration with a 12S battery pack, and to achieve this I am willing to increase my gear ratio by a factor of 1.2, and lower my motor amp limit by a factor of (1/1.2 = 0.8333), in this case the motor efficiency increases with 12S (green line, top left chart) and the motor heating decreases with 12S (purple line, top middle chart), while acceleration between the 2 systems is identical (yellow line, bottom left chart - vehicle thrust in pounds), and the top speed is nearly identical (yellow line, bottom left chart - vehicle thrust in pounds).
Still there is no bonus 20% wheel torque with this arrangement, only greater efficiency.
until you hit a tiny bump at the exact right time in the cycle to send a voltage spike through the line and burn up your DRV chip, throwing your face at the street
“but internet guy said he did it and was fine…”
We can talk theory all day, but something that works 80% as good at the extreme ends of the operating conditions and similarly good through the rest of the more normal conditions, but with a smaller failure rate, is clearly better.
Wow… Why do theory discussions always get so heated? It seems like there is a body of evidence that suggests 12s+ likely leads to premature failure. Being a forum community, we don’t have great data to confirm this, but between the 60V nominal rating being very close to 12s voltages and the empirical evidence, going beyond 10s should be considered “at your own risk”. We can all agree on that I think?
So then we should know what the reliability / safety trade off is. Which I contend is still 20 percent more torque (assuming you gear to the same top speed)
Prof, yes the benefit is because of the 1.2x change in gearing. I don’t see why you don’t have more torque though. Both setups have the same Kt and current. But the 12s setup has more gearing. Therefore more torque no? Said another way, the 12s setup is capable of more electrical wattage AND more efficiency, so it must be capable of more mechanical wattage?
in the last example the motor current setting on the 12S was reduced from 60a motor current to 50a motor current limit, a reduction factor of (1/1.2 = 0.8333)… in addition to increasing the gear ratio by a factor of 1.2… this is why they both have the same wheel thrust and top speed, and why the 12S system in the previous example had lower motor heating (purple line, top middle chart - ohmic heating watts 2 motors bldc).
but suppose instead you increase the gear ratio by a factor of 1.2 with the 12S system, but leave the motor current at 60a limit for both… now you have increased efficiency with 12S (green line, top left chart) & increased thrust with 12S (yellow line, bottom left chart - vehicle thrust in pounds), but the motor heating is the same for both (purple line, top middle chart - ohmic heating watts 2 motors bldc), top speed nearly the same for both (yellow line, bottom left chart - vehicle thrust pounds 2 motors bldc) & battery amps lower with 12S (purple line bottom right chart - battery amps 2 motors bldc).
I must admit that I’m genuinely surprised by the idea of people pushing the limits so far for little to almost no gain in real life scenario.
The thought of having a much higher chance of malfunction in my board while driving at 25+ mph and being thrown head first into tarmac or in front of the car, scares me to death. Therefore I use 10s wich I still think its a bit of a stretch.
Again guys electric boards don’t have redundancy one failure means total failure, and that could easy be the line between life and death for someone.
Stop giving dangerous advices to people, just because your are doing something and it went OK so far.
My i suggest that one of the guys with a good reputation makes a poll where people can vote about the rate of failure and the voltage they where using. If many enough people answer that could give us a somewhat clearer picture.
Maby
@Hummie, @professor_shartsis@chaka@onloop could be the right person.
Best regards from an engineer who has learnt d through his study that you should always aim to have at least 20 to30% headroom. Specially considering the outcome in case of a failure.
not that its a safe outcome but when i’ve had escs fail they havent launched me and instead just lost throttle. that could be very dangerous if leaning forward and expecting it, or if you were going downhill and you lose your brakes, but so far i cant blame a broken esc but can blame faulty receivers for many injuries.
~10 km/h speed increase going from 10s to 12s. That’s difference between holding up traffic and being able to move with traffic around where I live. Gear ratio sometimes can’t be tweaked. Now I have both torque and speed/E-MTB.
Dual drive, dual receiver. Redundancy right there.
I suggest you try a 10S battery connected to 2 independent drivetrains - each one having an ESC, a receiver, a motor, and a drive wheel. So the ESC are not connected together except for the main battery + and - wires
That way if you have a failure, it’s very likely that you will still have one wheel with power and brakes still
