Never seen this before, its not even on their website photos but it came in today and saw it soldered there. Is this safe to use? What the hell does it do?
1 Like
Looks like / is a tvs diodeā¦ Not a resistorā¦ It protects against voltage transients
5 Likes
Itās a diode.
As @approachinglogic mentioned itās probably for voltage spike protection. Never a good sign to see something as basic as that tacked on later. IMO thatās just an indicator of insufficient beta-testing.
What are the numbers/letters on it?
5 Likes
the letters are 5KP5 with a little 4 leaf clover like symbol below it
Yup, thatās a decently high power TVS protection diode to swallow voltage spikes. There should be at least one more number and maybe letters after the last 5 though.
2 Likes
Yup just noticed it now its 5KP51. at least i think its a 1, hard to tell since its just a straight line
1 Like
I feel like they added the diode after the many faults they were having with their esc. This is the first Iāve seen something like this.
2 Likes
yea iāve been looking all over the forum for pics and none of them have it, seems like a new addition. Iād have preferred a diff esc but I got this from a friend for a really good price, hopefully it wont fail spectacularly
Thanks.
That TVS diode seems to be rated at 51V. It will do nothing until a voltage spike of about 57V-63V or higher hits the positive terminal of the ESC. At that voltage the diode will start to shunt the voltage spike to the negative terminal and back down the black wire instead of the voltage spike going into the ESC. It will allow the voltage to go as high as about 82V max before clamping it and keeping it from rising any higher.
The more powerful the voltage spike the higher the clamping voltage is.
As long as the ESC is rated for 82V or higher the diode can do its job without having to worry. But since I see caps rated at 80V we have to hope the spike is shunted at a low enough voltage.
8 Likes
Itās flipsky. If it works, kudos. If not, I recommend MakerX. I vouch for them.
2 Likes
Thanks for the highly informative response! Would 63v caps have been better? I see alot of other 6.6 minis have 63v caps instead, without the diode there.
1 Like
No, a higher cap voltage rating is better.
If you could potentially have spikes as high as about 82V coming into the ESC (using that particular TVS diode) then you want the caps to have a voltage rating higher than that, higher than the highest voltage the ESC would experience.
63V caps would be even more susceptible to damage if the diode let through an 82V spike.
Odds are the diode will clamp the voltage to under 80V though. That 82V max clamping voltage spec is only when very high current levels are passing through the diode. This only happens if the diode is āswallowingā a very powerful spike.
The switch to 80V caps was probably done to better match up to the max voltage the protection diode would let through. Using the diode with 63V caps wouldnāt really add any protection to the ESC since the diode would let through a high enough voltage to damage 63V caps.
We canāt switch to a lower voltage rated TVS diode because they start to conduct current way below their max clamping voltage. This 51V rated diode starts conducting at around 57V-63V. That is a good match for a 12S pack or lower.
If we used a 45V rated diode, with a lower max spike clamping voltage of about 73V, that would ensure that the 80V caps are protected. But the 45V diode starts conducting at about 50V and thatās too low for a 12S pack that could be at 50.4V or even a bit higher.
8 Likes
Flipsky also responded to my email.
" Dear Sir, Thank you for connecting usļ¼Because some customers have reported that the current of this ESC is a bit unstable, we have newly installed tvs diodes to make the current of the ESC more stable in order to give customers a better experience.
Itās the big TVS we added to make the esc working more stable."
2 Likes
A fancy way to say faulty. But glad to see some improvements if any.
1 Like
Now that our paying customers have completed our beta-testing for us.
10 Likes
6 Likes
Funny, I have the Dual FSESC 6.6+ in my Sportster. Still rides great since last year. However, out of caution I stashed away a second FSESC in case mine ever crapped out, and having bought it a few months after, I noticed it indeed had the diode.
Very much a band-aid, sure. But, better a band-aid than an open wound. 
#positivevibesonly
3 Likes
Get a tiny cheap one like the FS 4.20 and just tape it to your skate tool, or even stuff it in the enclosure disconnected. Never know when itās gonna be needed! 
Edit: when I have some spare budget Iād actually like to do thatā¦
2 Likes
Any issues with voltage spikes or unstable currents in the one without the diode? When did you purchase your spare?