repetitive ESC failure on low power set up

[An average human]

i have been reading these forums and have been amazed at the quality and functionality of the bikes built, unfortunately the same could not be said for my bike. i have powered a bike using a small scorpion outrunner (2000w)
here is a picture of my bike (sorry if it's massive)

the problem is that i am getting through speed controllers at an expensive rate, please help me, i can't work out whats wrong as i am not exceeding the maximum voltage or amp rating of the controllers.

i have had 3 speed controllers fail me lasting a maximum of ~10 miles and a minimum of ~1.5 miles. They have all failed at low speeds and drawing few amps as i have a 30 amp circuit breaker, on my most recent failure (today) i was accelerating down hill using about 300 watts when my ESC failed.

here are a list of the esc's killed so far

mystery 100amp 22.2v
http://cgi.ebay.com/100A-100-Brushl...Control_Parts_Accessories?hash=item1c11ab916c

80 amp 22.2v
http://www.r2hobbies.com/eng/proddetail.php?prod=rcps81706_80

70amp 22.2v
http://www.r2hobbies.com/eng/proddetail.php?prod=rcps81708_70

i have little money as i am only 15, thank you in advance for helping

human

 

[Thud]

Human,
Here is a list of things that should help. (but keep in mind that low budget controllers are allways fragile on their best days)

#1 make the wires going from the battery to your speed controller as short as possible.(this is most important IMO)
-The wire lengths to the motor are far less important.

#2 Add a couple low "ESR" capacitors to the input side of the controller.
-Even the best controllers need this to survive. Watch the polarity.
Something like this:
http://www.newark.com/rubycon/50zlh1000m16x25/cap-alum-elect-1000uf-50v-radial/dp/38M6924?in_merch=New%20Capacitors&MER=NEWSO_S_C_Capacitor_None

Also, RC controllers are under the most stress at partial throttle conditions. I recomend to gear your bike so most of your motoring is done at full throttle.

If your controllers are programable-set the timing per the recomendations for the out-runner & eliminate any braking. (this will reduce current spikes flowing back into the controller) I really perfer my motors to free wheel (not spin while pedaling) to avoid this senario.

Good luck on the repairs & happy biking.

 

[An average human]

thank you for the advice, my wires are about 1.5 meters from battery to esc but why would wire length change anything? the cable i am using is massive - rated at 100 amps

i will shorten then anyway, how short do you recommend?

my setup does include a freewheel clutch on on the output from the box.

thanks for the resized attachment i have made the image on the link 66% smaller so it should now be fine if you re enable it

do you have any recommended brands for esc?

 

[Miles]

Explanation, here: http://www.rcgroups.com/forums/showthread.php?t=952523

 

[gwhy!]

I have run the mystery 100amp 22.2v and found it to be usable and reliable ( for the very limited hard use it had ) I fitted a much bigger heat sink onto fets ( the only time it got remotely hot was when programming it ) my battery leads were no more than 40cm long also extra caps were added. hope this helps.

 

[An average human]

very interesting, i feel so stupid.

i live in th uk so anything local is better (it seems wrong to pay lots on postage for such a cheap part), will these caps work? - http://www.technobots.co.uk/acatalog/Low_Impedance_105_Deg_C.html

i also have a few caps harvested from various audio amps but they are 43v and i have no idea of ESR.
do you recommend a high amp esc despite my low power set up? will i be ok with a 40 amp esc or is it better to go higher?

the mystery esc lasted me about 10 miles- thats my record at least they are cheap

thank you for helping and sorry for my ignorance.

 

[An average human]

off topic but miles and gwhy you are both in the uk! i bet you both run at least multi kw setups, how do you find the bike laws in the uk? i have been trying to work out how a policeman could workout if your bike is overpowered, they don't carry amp meters do they ???

should i gear my bike up a bit or up voltage and remove circuit breaker? it currently stops me from pulling 670w for extended amounts of time but i can still pull 1200w on "take off"

 

[Miles]

My set-up is limited by the capacity of the controller I'm using. In practice, because I'm running through a 3 speed hub gear, I rarely use as much as 750 Watts - so it's the equivalent to having a 250 watt continuous rated system :wink:

Whereabouts in the UK are you?

 

[An average human]

i live in forest row, sussex its about an hour from london

where do you live in the London?

 

[Miles]

Greenwich S.E. London.

 

[An average human]

thanks for the help everyone, i will order a new esc and implement changes.

where can i source low ESR caps in the uk?
http://www.rapidonline.com/Electron...g-Low-impedance-miniature-electrolytics/77042 are these ok?
how important is low ESR?
will any caps do?

sorry for the many questions

 

[gwhy!]

thanks for the help everyone, i will order a new esc and implement changes.

where can i source low ESR caps in the uk?
http://www.rapidonline.com/Electron...g-Low-impedance-miniature-electrolytics/77042 are these ok?
how important is low ESR?
will any caps do?

sorry for the many questions

These caps look ok, anything rated at above your battery voltage will be fine I was running a extra 2 500uf caps on my controller. The uk e-bike law sucks so I just brake it . But I do very little road riding, 98% of what I do is off road ( or up the local park ) I no longer use a rc esc due to the start up problems from a standing start I currently run a 3250w motor.

 

[Jeremy Harris]

............The uk e-bike law sucks so I just brake it . But I do very little road riding, 98% of what I do is off road ( or up the local park ) I no longer use a rc esc due to the start up problems from a standing start I currently run a 3250w motor.

I think many would agree with you, but it's worth noting that there is an ebike riding British police officer on this forum.......................... :wink:

Jeremy

 

[liveforphysics]

............The uk e-bike law sucks so I just brake it . But I do very little road riding, 98% of what I do is off road ( or up the local park ) I no longer use a rc esc due to the start up problems from a standing start I currently run a 3250w motor.

I think many would agree with you, but it's worth noting that there is an ebike riding British police officer on this forum.......................... :wink:

Jeremy

Then it's a good thing to know at least 1 cop out there is on our side, and understands the situation better than the others.

 

[gwhy!]

............The uk e-bike law sucks so I just brake it . But I do very little road riding, 98% of what I do is off road ( or up the local park ) I no longer use a rc esc due to the start up problems from a standing start I currently run a 3250w motor.

I think many would agree with you, but it's worth noting that there is an ebike riding British police officer on this forum.......................... :wink:

Jeremy

Dont get me wrong, If it was easy or indeed possible to make my e-bike legal I would but there is no middle ground. But what bike ( motor ) does this British police officer ride and do he run legal 100% of the time this is the question . 200watts max really do suck when anyone can jump on a horse and cause havoc.

 

[Miles]

200watts max really do suck when anyone can jump on a horse and cause havoc.

Yeah, we should be allowed at least one horse-power........

 

[gwhy!]

200watts max really do suck when anyone can jump on a horse and cause havoc.

Yeah, we should be allowed at least one horse-power........

Of course , then we can legally cause havoc on e-bikes :lol:

 

[Miles]

 

[deecanio]

Hi Average human,

i think you deserve massive kudos for what you have done so far, i think you may even be our youngest member? certainly youngest with a self built bike, impressive.
Couple of things, don't feel stupid, im 38 and you probably have more knowledge than me on the electrical side of things already
with the design you have gone for it would occur to me that you could have your esc and pack on top of your drive box, the extra weight would be negligable and your cables could be absolutely minimal in length and appearence.
I'm uk based too, along with a good few others here so you do have help reasonably locally, i have minimal tech experience to help you but if your strapped for cash (as most people your age are) i can maybe help you out with some sundries that you need.
Don't worry im not one of those people your parents warned you about on the internet :lol: but being as my knowledge is minimal i do like to help the community out any way i can, which is normally helping to fund something we need or giving my surplus parts to others that can use them.
Try what the guys have suggested and if you need caps or whatever i'll have them sent to you no probs, don't be asking for a new lithium pack and some marzochi forks now but if you need minor bits and pieces certainly give me a shout and i'll do my best to help you out.
Best of luck with the build above average human, so far so good!!!


D

 

[AussieJester]

Don't worry im not one of those people your parents warned you about on the internet :lol:
D

not what i heard...

Nice effort mate

KiM

 

[deecanio]

dont scare the boy off now Kim :lol:

D

 

[AussieJester]

 

[heathyoung]

Low ESR caps are needed because they will actually smooth the pulses at high frequencies, wheras non-low-esr electrolytics will just pass them happily along the chain. Properly done, you should also include a small value MKT (0.1uf or so) as close as possible to the speed controller PCB. The length of the battery leads is also inportant due to their inductance. These ESC's are very clever, but I always feel like they are a great way to drive real mosfets - these surface mount things just cant shed the heat well enough.

 

[liveforphysics]

Low ESR caps are needed because they will actually smooth the pulses at high frequencies, wheras non-low-esr electrolytics will just pass them happily along the chain. Properly done, you should also include a small value MKT (0.1uf or so) as close as possible to the speed controller PCB. The length of the battery leads is also inportant due to their inductance. These ESC's are very clever, but I always feel like they are a great way to drive real mosfets - these surface mount things just cant shed the heat well enough.

Loads of wisdom in your post healthyoung. I agree with 100% of it, and it all applies to anyone using an RC ESC.

 

[An average human]

thank you for answering my questions, do you think i could include my watt meter still ?

i was thinking about sourcing the caps, do you think i could use the ones harvested from the dead esc's ? - i have 3

does this wire length voodoo apply to other bike motors, i have a currie electro-drive 300w which was thrown out by a local cycle shop, i replaced the SLA's and it works fine but i have lengthened wires to about 1m :?

thanks for the offer deecanio, i think ill be fine as i have a massive parts "bin" (corner of garage) and a local dump which i can get things from, i got a 30cc petrol scooter for £5