Motor brakes or mechanical? - Page 3 - RC-Monster Forums

sleebus.jones · 01.03.2009, 07:39 PM

Quote:

Originally Posted by Ryu James

and mech brakes are definitley more efficient for your motor. with mech brakes you can have braking and reverse set to 0% so your motor is not working at all when you brake.

Huh? The motor isn't "working" when you brake, it's using the battery as a load and dumping the power there. Your argument doesn't make any sense.

FWIW, I've tested this with my eagletree and I can see amperage and voltage go UP when I brake, which is proof positive of regen braking. Think of it this way, if you didn't use regen braking, where would that energy go? Where's the load to dissipate it? Surely not through the FETs. It's regen.

Patrick · 01.04.2009, 03:27 AM

Quote:

Originally Posted by sleebus.jones

Huh? The motor isn't "working" when you brake, it's using the battery as a load and dumping the power there. Your argument doesn't make any sense.

FWIW, I've tested this with my eagletree and I can see amperage and voltage go UP when I brake, which is proof positive of regen braking. Think of it this way, if you didn't use regen braking, where would that energy go? Where's the load to dissipate it? Surely not through the FETs. It's regen.

Have a closer read of Ryu James's sentence that you quoted.

Ryu James · 01.05.2009, 05:09 PM

Quote:

Originally Posted by sleebus.jones

Huh? The motor isn't "working" when you brake, it's using the battery as a load and dumping the power there. Your argument doesn't make any sense.

FWIW, I've tested this with my eagletree and I can see amperage and voltage go UP when I brake, which is proof positive of regen braking. Think of it this way, if you didn't use regen braking, where would that energy go? Where's the load to dissipate it? Surely not through the FETs. It's regen.

my point is that the motor is not having to "work" to slow down the vehicle cuz the mech brakes do this. i am sure energy is still being spent in small amounts of course but the motor is basically freely rolling if you set your esc brakes to 0% and reverse to 0%. it must be working less than it would be when slowing down a 9 lb truggy all by itself, right?

Arct1k · 01.05.2009, 05:40 PM

No - its not "working" as a motor it is working as a "generator" and hence creating elec (and heat) from the kinetic energy of the car.

shaunjohnson · 01.06.2009, 02:42 AM

sleebus,
the egle tree probably shows a voltage increase when braking because voltage drops under load...as soon as you get on the brakes the voltage is probably picking up what it was losing under load

but if the voltage spike was above it's "resting" voltage then i guess you are right

marzac2 · 06:11 AM

Quote:

Originally Posted by Arct1k

No - its not "working" as a motor it is working as a "generator" and hence creating elec (and heat) from the kinetic energy of the car.

No. The motor would only be working as a "generator" while you are "free rolling".

The moment you apply brake, you are asking the motor to stop a 9lb vehicle. And this comes at a cost = energy.

Do you believe that making a motor alone stop a 9lb vehicle, that it would not spend any energy doing so? Are you saying that it would actually re-gain energy making this happen?

_paralyzed_ · 01.06.2009, 03:42 AM

Quote:

Originally Posted by marzac2

No. The motor would only be working as a "generator" while you are "free rolling".

The moment you apply brake, you are asking the motor to stop a 13lb vehicle. And this comes at a cost = energy.

Do you believe that making a motor alone stop a 13lb vehicle, that it would not spend any energy doing so? Are you saying that it would actually re-gain energy making this happen?

Yes that's what he's saying. Have you read the entire thread?

regenerative braking is used. You cannot lose energy, only transform it. The stable temps on the mmm esc prove regenerative braking works, otherwise your esc would cook because that stopping power has to go somewhere, either as heat on a brake disc, heat on a blown esc, or back to the battery in the case of the MMM. Eagle tree graphs prove energy is regained.

Arct1k · 01.08.2009, 08:07 PM

Correct it is working to stop the car - but it comes with a benefit "energy" that the motor/esc puts into the battery...

Ryu James · 01.09.2009, 08:10 AM

somebody, anybody, i want to see these stats that PROVE that energy goes back into your battery when you use motor brakes and i also want to see how much. is it a trace amount? or are we talking 10 extra minutes of run time here? i think it is all myth. i agree with what Marzac is saying. the energy graph shows an increase when the brakes are applied only because there was a large drain on energy when the throttle was on. i am very skeptical of the "regenerative braking" theory as it is so convincingly put. somebody prove me wrong. back up these claims please!!

George16 · 08:26 AM

Quote:

Originally Posted by Ryu James

somebody, anybody, i want to see these stats that PROVE that energy goes back into your battery when you use motor brakes and i also want to see how much. is it a trace amount? or are we talking 10 extra minutes of run time here? i think it is all myth. i agree with what Marzac is saying. the energy graph shows an increase when the brakes are applied only because there was a large drain on energy when the throttle was on. i am very skeptical of the "regenerative braking" theory as it is so convincingly put. somebody prove me wrong. back up these claims please!!

Why don't you read about regenerative braking om 1:1 cars? It's the same but on a different scale. It might not be a lot but it's still there.

I remember Patrick posting about this particular topic though I'm too lazy to search.

Edit - Read this:
http://www.teslamotors.com/blog4/?p=58

Ryu James · 01.09.2009, 08:58 AM

i will check it out and do some searching. i am not saying that i dont believe it but i would like to see some actual graphs or something to prove this. obviously they exist somewhere for so many people to subscribe to this concept.

Ryu James · 01.09.2009, 09:08 AM

i read that link george posted. interesting. the Tesla Roadster sounds like an interesting car. i have always wondered why they cant build full scale cars to be super power electrics like our 1/8's. i mean, if they have the technology to build these small motors that give us like 500 scale horsepower then they should be able to just increase the size and make a powerful real car. like a Ferrari with a Neu the size of a 5-gallon bucket and a lipo the size of a large couch cushion. lol. could you imagine. how crazy would that be.

the Tesla roadster does 0-60 in 3.9 and has max rpm of 14,000. not bad.

http://www.teslamotors.com/

Ryu James · 01.09.2009, 09:13 AM

http://en.wikipedia.org/wiki/Regenerative_brake

George16 · 09:15 AM

The main reason (after watching the Tesla electric car on History channel) behind the impractibility of pure electric cars is the weight of the batteries. The technology is quite slow in reducing the weight of Lithium-Ion but it's getting there.

By the way, the 3.9 sces from 0-60 is way better than a lot of comparable sports cars.

Mozzy · 01.09.2009, 11:21 AM

Well, I don't know what happened when I changed from motor braking back to servo braking on my CRT.

My runtime was increased by a scrape over 4 mins with mechanical brakes. I use a BLS451 for brakes & a BLS352 for steering. Someone else better do an outright comparison, cause, I think I just gained runtime.
Figure that one out geniuses. :-)