Test1 RedCat Earthquake 8e

[radioman193]

all i can say

Is do testing and you will see the esc has 0 output under breaking.
and look at how the voltage is sent to the motor under breaking.

Under realworld bench testing.
just test a few esc/motor combos on the bench.

I need not say more on this as the proof is easy to find
and dont Overthink and make it harder than it is.

and remember this just because a motor runs on just say 6v @ 3 amps
thats not saying that it will OUTPUT 6v @ 3a as a Generator cause it wont.
so this blows away the number tossing game out the window.

there just might be Some or a few Rc Brushless esc's that do utilise regernerative breaking but i myself have not found one.

just do some Simple testing that others and i can do to see .......
And if i am found Wrong i will drop off ALL Rc forums completely never to post again .

[J57ltr]

Here is some info:

If Patrick said it you can pretty much take it as gospel.

http://www.rc-monster.com/forum/show...=regen+braking

Originally Posted by othello

You will also notice regenerative braking when hooking up an eagletree logger to a car setup.



Driving my truggy on asphalt with a Neu 1512/2Y (1400kv), Jazz 55 ESC and 10s1p A123. I marked the amp and voltage peaks where i applied brakes. The green line represents motor rpms. The eagletree logger records positive Amps (not negative amps) and voltage does rise instead of falling -> the battery is recharged. Amp Peaks around 15-20A with voltage rising by 1.3-1.4V

A similar behaviour can be seen with MMM and BK ESC.

Quote from Pdelcast about MMM EscQuote:
The braking is regenerative because it has to be -- can't dump that much energy anywhere but back into the battery. (The battery is used as a load, but using a battery as a load mean charging the battery...)

It is not, however, optimized.

Still gets fairly good efficiency up to about 35% braking power -- above that the conversion efficiency gets lower.

[radioman193]

i want to see a way to reproduce these "facts" in a way that Everyone can try and see.
as i took the motor and esc out of the truck and mounted it on the bench and powered it up and did some more testing with it.

and with the motor at 75% brake force and with breake on i drove the brushless motor with another Brushed motor runing on 12v @ 15amp .
and the brushless esc did get Very warm But did NOT show a positive output on the battery connector all i got was a constant dip or drop in voltage as the esc applied more voltage to the Brushless motor to try to hold the motor still .

you cant make the test more Simple than this setup and its one EVERYONE can do.

Note when testing
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 or in place.

its just a way to test this that ALL or everybody can do and only takes 10 to 15 minutes to setup.
Videos are welcome as it is easy to "say" but better to prove.

[BrianG]

I don't think it's that simple. If you are running at 75% brake force, you are just resisting the motor turning. Therefore, any induced (regenerated) voltage will not exceed the supply (battery) voltage and no charging current will flow. Remember, these motors are ~35% efficient (according to patrick IIRC) when braking vs ~90% when running. So it makes sense you'd have to have a motor with decent amount of kinetic energy behind it (vehicle weight at speed) and stop quickly to generate a visible amount of regen current.

Patrick does explain, in depth, how regen braking works: http://www.rc-monster.com/forum/show...0&postcount=57

[snellemin]

All my logs show Voltage spikes during braking and some brake current. This is a good read why the voltage increase during braking by MGM Compro.

http://mgm-compro.com/pdf/en-motor-braking-050409-g.pdf

[snellemin]

Originally Posted by radioman193

i want to see a way to reproduce these "facts" in a way that Everyone can try and see.
as i took the motor and esc out of the truck and mounted it on the bench and powered it up and did some more testing with it.

All you need to be able see the voltage spike and some reverse current during braking, is a Datalogger like the one I use by Eagletree. As simple as plugging it in series between your battery and ESC.

[Arct1k]

I don't see why one's knowledge gaps should cause total forum abandonment but on this I really think that science (Brian and Patrick) is on the side of regen braking.

Best of luck - Please let a mod know if you want your account locked ;)

[BrianG]

Originally Posted by Arct1k

...Best of luck - Please let a mod know if you want your account locked ;)

Can we even do that?

[J57ltr]

Originally Posted by radioman193

all i can say

just do some Simple testing that others and i can do to see .......
And if i am found Wrong i will drop off ALL Rc forums completely never to post again .

No need to drop of the face of the earth for being wrong. I have been wrong several times. I don’t have a license to be an Electronic Tech, but I do have a degree (as do several others here). Here is a simple test. I am sure you must have a meter that has a peak hold function on it. Strap that on your RC car, turn on the peak hold feature connect to the battery and take it out. Do some hard braking and see what happens.

Jeff

[aqwut]

Radioman..
Try this,
put a AC volt meter on one of the motor cables and see what it reads.. just for sh*ts and giggles...
lets say you're cruising down the streets @ 40MPH with the RC car.. and the motor is spinning while coming to a stop, that energy must go somewhere.. Because if you connect 2 brushless motors together and give one of them a spin, the other one will spin also.. I'm assuming that some RC ESCs do not allow that energy to be sent back to the ESC or battery or whatever.. but the energy just doesn't disappear. Maybe the proper term is not regenerative braking? Maybe regenerative slowing down.. LOL.. but give her a test..

Anyways, it's cool to be wrong.. I'm wrong all the time.. but once and a while I am correct... have a good one guys..

[BrianG]

Originally Posted by J57ltr

No need to drop of the face of the earth for being wrong. I have been wrong several times. I don’t have a license to be an Electronic Tech, but I do have a degree (as do several others here). Here is a simple test. I am sure you must have a meter that has a peak hold function on it. Strap that on your RC car, turn on the peak hold feature connect to the battery and take it out. Do some hard braking and see what happens.

Jeff

I have to add that some ESCs, such as the MMM, do have a TVS device which limits the amount of peak voltage generated during hard braking. IIRC, it's rated somewhere between 26 and 28v, which means that any voltage peaks above its rating are essentially shunted to ground. This means that you might not truly measure the full voltage peak potential. But really, any value above the battery voltage should indicate regen braking, because any voltage above the battery voltage will cause current to flow from the higher to lower potential, which is from the motor to the battery.

[J57ltr]

Looks like he is only running 4S so it shouldn't be a problem, but thanks for pointing that out.

Jeff

[TexasSP]

This is all I have to say:

[aqwut]

Originally Posted by texassp

this is all i have to say:

lol...

[radioman193]