# LiPo and brushless braking surge



## darkultra (Dec 30, 2004)

Hi!

Is it true that braking with a brushless setup will charge your pack, and a braking surge can be up to 100Amps on monster trucks equipped with a BL?

would that be mean to a LIPO pack like the PQ4S-4400N

I was thinking of running my e-maxx and hacker C50/comp ESC with this pack.


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## DynoMoHum (Sep 25, 2001)

I don't know... where did you hear that?

I somewhat doubt that it's true, however I do not know that for sure.

On a brush motor, it certianly would be possible that large amounts of current get genenerated by the motor druing braking. What if anything gets done with it is then up to the ESC. I do know that some ESC's for brushed motors were able to (suposedly) put some of this back into the battery pack.

On a brushless motor, it would seem the trick would be harder to do... but then making a brushless motor run is harder to do as well and they do that, so I still don't really know the answer to your question. I am however currious if you know of any other discussion about this on the internet? and/or where you heard this.


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## McLin (Dec 5, 2001)

With 100 Amps, I could weld 1/2 steel!! Now MAYBE 100 amps for 1/10th of a milly second!


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## darkultra (Dec 30, 2004)

Hrere I found where I read it from.



_7. Yes, these are regenerating ESCs, so some of the braking power is used
to charge your batteries for longer run time. 

8. The greatest problem with brushless ESC is managing the back current
from braking. Apparently these can easily spike over 100 amp which causes the
ESC to shut down protectively until the spike is over. Apparently the higher
the KV (rpm per volt) the motor, the more prone it is to this problem._

http://groups.google.no/groups?q=100+amp+which+causes+the++ESC+to+shut+down+protectively+until&hl=en&lr=&selm=20010225001710.04970.00002026%40ng-cd1.aol.com&rnum=1


_Yes. Power will typically flow back into the battery during deceleration, or whenever the motor is spinning faster (because it is pushed, or inertia) than it would at the applied power level._

http://www.roboteq.com/faq.shtml#regenfaq


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## DynoMoHum (Sep 25, 2001)

The key word in that blurb being 'spike', and well it's probably not that hard to imagine spikes like that. Brushed motors probably also spike quite high... Basicly a motor and a generator are the same beast... they just do things in the oposist direction.


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## wkstill (Mar 17, 2005)

hmm.. Hybrid Nitro w/Brushless & Nitro Motor


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## darkultra (Dec 30, 2004)

Like the Toyota Primus !

http://www.toyota.com/prius/

hmmm cleaner city air and less city noise hmm mmm


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## Craps (Mar 22, 2005)

This is a new one to me????


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## starluckrc (Feb 18, 2005)

Castle will be incorporating regenerative breaking into the HV Maxx. Short curent spikes will most like be absorbed by capacitors and shouldn't be a huge threat in a properly designed esc.


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