Test1 RedCat Earthquake 8e
 

Another First good testing day.....
Today I tested out my RedCat Earthquake 8e
and the Motor gets Warm Fast the way i was usen it in this video.
The batteries get warm
The ESC gets luke warm
...Over all the truck has WAY more power than it needs!
!!!!!!! NEVER run it Without a Wheelie bar !!!!!!
Over all the truck is a Good truck for $299.

Nothing big just a testing video
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This truck KiCkS Butt
WAY more power than it needs!

That's not a good sign - what motor is it? A good brushless motor should be able to handle that type of driving without any problems.

oh yes its 100% WaterPROOF

i used Epoxi to waterproof it.

http://a5.sphotos.ak.fbcdn.net/hphot..._2003281_n.jpg

ESC before waterproofing

http://a4.sphotos.ak.fbcdn.net/hphot..._8073435_n.jpg

http://a7.sphotos.ak.fbcdn.net/hphot..._1945239_n.jpg

After Waterproofing

http://a1.sphotos.ak.fbcdn.net/hphot..._5949096_n.jpg

http://a3.sphotos.ak.fbcdn.net/hphot..._6349143_n.jpg

melt water was flooding the esc here

http://a6.sphotos.ak.fbcdn.net/hphot..._6789018_n.jpg

it does handle it.
just after 20 minutes of full throttle puntch and full brake to full puntch.
the motor is about 130 with NO fan on it. >>> to ME <<< 130 is hot
the esc was 91
tested with ir .
the motor is a 2230Kv 540 .

I have to say that using that epoxy to waterproof your esc may cause you problems down the road. Specifically I fear that you may not be able to dissipate any excess "EPE" that will built up in your esc, leading to premature failure. For more information, be sure to read this post carefully:

http://www.rc-monster.com/forum/show...0&postcount=22

I hope this helps.

I vote that the above linked post should be stickied. All in favor??:yipi:

thanks
but i have had NO problems with any esc's i have done in the past for others or myself ....
others i have done have been working for over 3 years sofar with no problems .
i do know what needs Proper heat dissipation and some other factors.
other things have been added to the esc for reasons of safety and longevity.
i have been doing electronics for far to many years to go about things blindly.

But thanks for your concern.

the above link was a Fun read
but only applies to a device that is used in a way that it was NOT intended to be used OR was of a Bad Desing to start with
or used out of specification....
like "More brake load /force" than the fet's can shunt to gorund and with that type of electron power energy flow or "EPE" as was put ..
look at it like this ..................JUST an EXAMPLE >> if a FET can handle 5000 electrons per ms shunt to ground and you force 20000 to it just what do you think will happen?????? you will end up with a electron saturation within the device ...and in a short way to say you will get your Magic smoke.
99.5% of the time this is the cause of the ESC letting out the Magic smoke people usen a motor that draws more current and Or present more shunt load than the ESC can TRUELY handle over a period of time leading to a catastrophic failure of the FET's in the ESC.

i think its funny when i see people saying ....
when you apply brake the power goes back to the battery on a rc.......
NOT!!!!!
the motor can otuput WAY OVER 10amps on brake
so basicly thay are saying thay are putting OVER 10amps of power back into the battery...OMG.. "BOOM"!!!
the brake load is shunted to ground not put back to the battery......
we are not talking like a hybrid car here a rc esc is very simple in its Desing.

you've got it wrong radioman.

R/C esc's are quite sophisticated and do indeed have regenerative braking.

"Energy is neither created or destroyed" You can't just "shunt to ground" the multi kilowatt output of motor braking. THAT would blow the esc.

And that many watts of motor braking cannot be simply dissipated as heat.

The energy does indeed go back into the batteries. That is why a battery with a low internal resistance is so critical.

You seem to be making a lot of assumptions based on your prior electrical knowledge. I feel you should learn about the new technology before you claim to understand it.

i think someone is drinking bongwater and huffing krylon fusion paint

:slap:

if you "say"
Thats cool
it looks like i will see if Or when it dies.
or any of the others do.

HMMmmmm.

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As was said

"That is why a battery with a low internal resistance is so critical."

low internal resistance. Measured in milliohms, the internal resistance is the gatekeeper that, to a large extent, determines the runtime. The lower the resistance, the less restriction the battery encounters in delivering the needed power spikes. A high mW reading can trigger an early 'low battery' indication on a seemingly good battery because the available energy cannot be delivered in the required manner and remains in the battery.


These might help you.

http://www.popularrc.com/?p=382

http://batteryuniversity.com/partone-22.htm


i was wrong to a point on how the brake works on a brushles esc............
BASICLY
not going into pulse timing or other detailed information that is not needed.

when you brake 2 coils get a voltage 1 on eatch side of the armature
the harder you brake the higher the voltage..... in turn slows the armature and or holds it in place.
the esc can detect the rotation and will very the voltage to said coils as is needed as you increase or decrease your brake force
upto the esc's Brake amperage .
but still does not offload voltage to the battery.

Sorry bu I do think I'm going to have to go with Patrick and my Eagletree in that ESCs do have regernerative breaking and that some (not all) of the energy is passed back into the battery.

The only other option would be for the ESC to convert the energy into heat - now a 30lb baja at 52mph.

Kinetic Energy = m x v x v
KE = 13.6kg x 23.3 m/s x 23.3 m/s = 7.3 KJ

Braking in 3 seconds

KW = 7.3/3 = 2.9KW of energy to disipate

Yes this assumes no mechanical drag / surface friction etc but you get the idea.

I've been meaning to add some kind of brake calculator thingie to my site. Thanks for posting the formulas Chris; saved me from getting them myself. :smile:

Ok, now back to your regularly scheduled thread topic...