ESC limits: amps vs turns

[V. Grovestine]

Perhaps a critical piece of information is missing from some ESC
specifications, but I am baffled by the apparent lack of correlation
between continuous/peak amperage values and motor turn limits.

After an 8 year hiatus the R/C bug bit me again last winter and I popped
for a Traxxas Rustler kit. The following summer I picked up a Duratrax
Intellispeed Autosport ESC foolishly thinking that the 20T Stinger would
keep me happy for a while.

In the past, I've run a Speedworks Tony Neisinger (14x4) with a Futaba
MC112B (rated for 27T, I believe) without incident...er...until the car
(a Tamiya Boomerang), traveling much too fast, clipped a fence post!

With that in mind and contrary to the specs, I would like to couple the
Autosport with a Trinity Speedworks 350 (18x2, and hardly used) for
bashing around.

Ultimately my question is, are the turn limits on ESC stated as a simple
precaution for the non-electrically inclined person? Or is there
another factor at play? On the surface it strikes me as odd that my
Intellispeed Autosport rated at 128A cannot handle a mild modified, yet
an LRP F1, for example, can--Even with a peak current that less than the
Autosport's continuous rating.

Can someone clear up this mystery for me?

Some entry-level/sport example ratings:
Duratrax Intellispeed Autosport
- 128A/440A, 20T limit
Duratrax Intellispeed Mild Modified
- 192A/660A, 16T limit
LRP Runner Plus
- 20A/80A, 18T limit
LRP F1 Reverse
- 30A/110A, 16T limit
LRP F1 Super Reverse
- 35A/170A, 12T limit
Novak Explorer II
- 150A, 15T limit
Futaba 230
- 90A, 20T limit

Tkx folks,

--Vincent

[Col]

"V. Grovestine" <vgrovest@hotmail.com.xx> wrote in message
news:qok4c.4719$kc2.104735@nnrp1.uunet.ca...
> Perhaps a critical piece of information is missing from some ESC
> specifications, but I am baffled by the apparent lack of correlation
> between continuous/peak amperage values and motor turn limits.
>
> After an 8 year hiatus the R/C bug bit me again last winter and I popped
> for a Traxxas Rustler kit. The following summer I picked up a Duratrax
> Intellispeed Autosport ESC foolishly thinking that the 20T Stinger would
> keep me happy for a while.
>
> In the past, I've run a Speedworks Tony Neisinger (14x4) with a Futaba
> MC112B (rated for 27T, I believe) without incident...er...until the car
> (a Tamiya Boomerang), traveling much too fast, clipped a fence post!
>
> With that in mind and contrary to the specs, I would like to couple the
> Autosport with a Trinity Speedworks 350 (18x2, and hardly used) for
> bashing around.
>
> Ultimately my question is, are the turn limits on ESC stated as a simple
> precaution for the non-electrically inclined person? Or is there
> another factor at play? On the surface it strikes me as odd that my
> Intellispeed Autosport rated at 128A cannot handle a mild modified, yet
> an LRP F1, for example, can--Even with a peak current that less than the
> Autosport's continuous rating.
>
> Can someone clear up this mystery for me?
>
> Some entry-level/sport example ratings:
> Duratrax Intellispeed Autosport
> - 128A/440A, 20T limit
> Duratrax Intellispeed Mild Modified
> - 192A/660A, 16T limit
> LRP Runner Plus
> - 20A/80A, 18T limit
> LRP F1 Reverse
> - 30A/110A, 16T limit
> LRP F1 Super Reverse
> - 35A/170A, 12T limit
> Novak Explorer II
> - 150A, 15T limit
> Futaba 230
> - 90A, 20T limit
>
> Tkx folks,
>
> --Vincent

I have a Hitec SP-560+ and it supposedly has a 800amp max rating and a 200
amp continuous. I have no idea how these are arrived at. A ESC of a friends
with a lesser rating seems much faster. I am as confused as you.

Col.

[RS]

800 amps! a 200 amp welder will weld 1/2 steel at that rating. It is all
bull. pump 800 amps through your car starter and you will not have a car.
The only companys that give realistic ratings for their ESC's are
AstroFlight and Vantec, check them out for your self. Company's like Novak
are dreaming in their sleep.

"Col" <kioraspam@ntlworld.com> wrote in message
news:7Dn4c.1284$p%6.422@newsfe2-gui.server.ntli.net...
> "V. Grovestine" <vgrovest@hotmail.com.xx> wrote in message
> news:qok4c.4719$kc2.104735@nnrp1.uunet.ca...
> > Perhaps a critical piece of information is missing from some ESC
> > specifications, but I am baffled by the apparent lack of correlation
> > between continuous/peak amperage values and motor turn limits.
> >
> > After an 8 year hiatus the R/C bug bit me again last winter and I popped
> > for a Traxxas Rustler kit. The following summer I picked up a Duratrax
> > Intellispeed Autosport ESC foolishly thinking that the 20T Stinger would
> > keep me happy for a while.
> >
> > In the past, I've run a Speedworks Tony Neisinger (14x4) with a Futaba
> > MC112B (rated for 27T, I believe) without incident...er...until the car
> > (a Tamiya Boomerang), traveling much too fast, clipped a fence post!
> >
> > With that in mind and contrary to the specs, I would like to couple the
> > Autosport with a Trinity Speedworks 350 (18x2, and hardly used) for
> > bashing around.
> >
> > Ultimately my question is, are the turn limits on ESC stated as a simple
> > precaution for the non-electrically inclined person? Or is there
> > another factor at play? On the surface it strikes me as odd that my
> > Intellispeed Autosport rated at 128A cannot handle a mild modified, yet
> > an LRP F1, for example, can--Even with a peak current that less than the
> > Autosport's continuous rating.
> >
> > Can someone clear up this mystery for me?
> >
> > Some entry-level/sport example ratings:
> > Duratrax Intellispeed Autosport
> > - 128A/440A, 20T limit
> > Duratrax Intellispeed Mild Modified
> > - 192A/660A, 16T limit
> > LRP Runner Plus
> > - 20A/80A, 18T limit
> > LRP F1 Reverse
> > - 30A/110A, 16T limit
> > LRP F1 Super Reverse
> > - 35A/170A, 12T limit
> > Novak Explorer II
> > - 150A, 15T limit
> > Futaba 230
> > - 90A, 20T limit
> >
> > Tkx folks,
> >
> > --Vincent
>
> I have a Hitec SP-560+ and it supposedly has a 800amp max rating and a 200
> amp continuous. I have no idea how these are arrived at. A ESC of a
friends
> with a lesser rating seems much faster. I am as confused as you.
>
> Col.
>
>

[Col]

"RS" <RS@nospam4me.com> wrote in message
news:AYq4c.5396$R37.864@read1.cgocable.net...
> 800 amps! a 200 amp welder will weld 1/2 steel at that rating. It is all
> bull. pump 800 amps through your car starter and you will not have a car.
> The only companys that give realistic ratings for their ESC's are
> AstroFlight and Vantec, check them out for your self. Company's like Novak
> are dreaming in their sleep.

Yes, I agree, but even so they must have seen the figures while testing to
be able to quote them. Makes you wonder how though.

Col.

[Jonathan Hodgson]

On Fri, 12 Mar 2004 18:50:05 -0000, Col wrote:

> "V. Grovestine" <vgrovest@hotmail.com.xx> wrote in message
> news:qok4c.4719$kc2.104735@nnrp1.uunet.ca...
>> Perhaps a critical piece of information is missing from some ESC
>> specifications, but I am baffled by the apparent lack of correlation
>> between continuous/peak amperage values and motor turn limits.

>> Some entry-level/sport example ratings:
>> Duratrax
>> - 128A/440A, 20T limit
>> - 192A/660A, 16T limit
>> LRP
>> - 20A/80A, 18T limit
>> - 30A/110A, 16T limit
>> - 35A/170A, 12T limit
>> Novak
>> - 150A, 15T limit
>> Futaba
>> - 90A, 20T limit

My M-Troniks: 350A, no limit (happily runs a 10x2)

> I have a Hitec SP-560+ and it supposedly has a 800amp max rating and a 200
> amp continuous. I have no idea how these are arrived at. A ESC of a friends
> with a lesser rating seems much faster. I am as confused as you.

Col: if your friend's ESC "seems faster" at full throttle, then either
there's something wrong with yours (high-point set up wrong?) or it's
down to motor or cells, not the ESC. The noticeable differences
between "good" and "less good" ESCs are to do with part-throttle
control and efficiency, and brakes - not all-out power.

Back to the main thread, AIUI the nominal ratings are based on 25°C
(~77°F) and the "instantaneous" current means just that. A 12T motor
or less will stall (read launch) at 80A or more given decent cells,
and will probably maintain that for a significant fraction of a second
at the start of a race and whenever you crash and have to re-start.

Similarly, if I can dump 2400s in six minutes or so then that's a 24
amp average current - probably more like 48 amps for half the lap, and
0 for the rest - which will heat the FETs up considerably.

My guess is that LRP's figures (and other low-sounding ones) are
adjusted to allow for realistic temperatures and times.

Jonny

[Rick Russell]

In article <qok4c.4719$kc2.104735@nnrp1.uunet.ca>,
V. Grovestine <vgrovest@hotmail.com.xx> wrote:

> Ultimately my question is, are the turn limits on ESC stated as a
> simple precaution for the non-electrically inclined person?

Yes.

> Or is there
> another factor at play?

Warranties. Duratrax equipment is aimed at novices, while LRP is aimed
at hardcore people. I would guess that Duratrax bumps down the
specifications to create a large "safety zone".

> Some entry-level/sport example ratings:
> Duratrax Intellispeed Autosport
> - 128A/440A, 20T limit

Those ratings are probably for the FETs themselves. The ESC may not be
able to handle that much continuous current, due to heat dissipation
issues and that sort of thing.

With that said, it's perfectly safe to experiment. If you can do a few
high-power runs up and down the pavement without heating up the ESC,
then you're safe.

Rick R.