Esc For Clod Buster

[Rob Buckle]

Folks,

This thread is intended to help me understand the differences between MSCs and ESCs, how they relate specfically to my Clod Buster (currently with a stock MSC) and hopefully to provide me with some recommendations based on criteria I think I have, but likely additional criteria you will point out along the way.

My knowledge of MSCs and R/C electronics (and electronics generally) is almost nonexistant so please excuse my ignorance, but my understanding is that my MSC has Stop and 2 specific Forward/Reverse speeds. I'm guessing that one difference between an MSC and ESC is that the latter offers linear (instead of stepped in the case of an MSC) acceleration from Stop right up to full speed Forward/Reverse. Is this correct?

I have now read a fair bit about Li-Po batteries and understand that one does not fully deplete them before recharging, and that to manage the risk of depleting the battery you can either install a buzzer device, or a cut off device. Presumably the buzzer device does only that, and it is up to you to shut down the truck? With cut off devices I believe you can have a 'soft' or 'hard' cut off, where a 'soft' cut off reduces but does not completely eliminate power to the motors whereas a 'hard' cut off simply shuts off power to the motors. Is this correct?

I understand that the Clod Buster is different from most R/C cars in that it has two motors. To allow for this I know the Tamiya TEU-103BK can be adopted. However, my understanding is that this ESC can only be used with stock 540 or Tamiya Sport Tuned motors, presumably because these motors do not draw as much current as more powerfull (brushless?) motors. Is this correct? I have also read elsewhere in the forum something or another about Tamiya ESCs not being compatible with Li-Po batteries. Can anyone enlighten me? Additionally, is an alternative method of using an ESC with the Clod Buster to use 2 ESC's - one for each motor - or is this a poor/not required solution?

Reading this post, I don't understand why changing ESC would involve also changing driveshafts. Can somone explain why this would be the case?

It is my understanding that if experimenting with various motors, as I will be, it is better to go with a higher calibre (more powerful?) ESC so that it can handle whatever motors I pair it with (and be safer in any event because it will effectively be overkill?). Assuming this to be true, can anyone give me recommendations? Also, I would be very interested to hear why some suggested ESCs are not recommended as this will better help me understand about ESCs generally.

Sorry to ask so many questions in an increasing number of threads. It has been a very long time since I last was into R/C and even at that time was nowhere near as learned as those who have contributed to threads I have started. I would like to take this opportunity to thank those who respond; I am learning so much and with all the researching I am doing elsewhere online I am finding R/C fascinating!

Many thanks,

Rob

[Dombrasky]

http://www.tamiyaclub.com/forum/index.php?showtopic=39323

Its an old post,might be some use

[TWINSET]

Reading this post, I don't understand why changing ESC would involve also changing driveshafts. Can somone explain why this would be the case?

Me either, but then Clods don't have driveshafts anyway, so it's irrelevant

I'm guessing the option to run 14.4v (via the Traxxas ESC) thru Tamiya's 7.2v TXT driveshafts would result in the odd part failure, thus necessitating an upgrade in hardware at some point

[Rob Buckle]

Me either, but then Clods don't have driveshafts anyway, so it's irrelevant...

Ah, yes, I was thinking of the axles.

(Note to self: must remember correct terminology )

[Rob Buckle]

In thread posts where people discuss using two batteries, what is the end result? Do the motors turn twice as fast and run for half as long, or do they turn at the same speed as one battery being used but last twice as long (see what I mean about ignorance?)?

[TWINSET]

In thread posts where people discuss using two batteries, what is the end result? Do the motors turn twice as fast and run for half as long, or do they turn at the same speed and last twice as long (see what I mena about ignorance?)?

It depends how you wire everything

You can wire two 3000mah 7.2v batteries to give you either 7.2v 6000mah ('twice' the runtime), or 3000mah 14.4v ('twice' the speed)

'twice' is approximate, as the extra battery will have weight consequences so there may be a tiny forfeit because of it

It's called either series or parallel wiring

Pretty sure series increases the voltage, but I could be wrong.

If you're sticking with the stock Clod wheelbase etc, don't go wallet-out mental on speed straight away, it doesn't take much to put a Clod on it's roof (next search; wheelie bars )

For Clod motor wiring, you want parallel though (motor wiring, not battery wiring) - search the 'monster' forum just for the word parallel and you'll find plenty

[Rob Buckle]

It depends how you wire everything...

Thanks TWINSET, I understand now.

If you're sticking with the stock Clod wheelbase etc, don't go wallet-out mental on speed straight away, it doesn't take much to put a Clod on it's roof...

No worries; I may be a bit prolific on the forums at present but I fully intend on taking things one step at a time. I have a pair of Sport Tuned motors on the way which I intend to compare against the stock 540 motors. I may then decide to change my stock MSC to a Tamiya TEU-103BK ESC as I know enough about ESCs to know that this is a suitable replacement that can handle the Sport Tuned motors. Again, I am likely to compare performance against the stock MSC. If by this time I am still unsatisfied with the Clod Buster's performance I imagine I will go for lower turn motors than the Sport Tuned (though I believe this may compel modification to the 4 link arms connecting the gearbox to the chassis as I have read that larger motors do not fit natively) and a heavyweight ESC.

In terms of measuring performance I thought I'd mark off a set distance along a road, say 100m, and time the Clod Buster from a standing start to flying finish. A rather basic test I know, but at least it allows me to see the difference in contibution each part makes to perfomance. More importantly, it compares apples to apples. Sound reasonable?

Question: In this post, final paragraph, why would someone use a low turn motor in conjunction with gearing down? Wouldn't gearing down a low turn motor simply be the same as installing a higher turn (and likely cheaper, therefore) motor at 'normal' gear ratios? In other words doesn't one (low turns) counter the other (gearing down)?

[mike_o]

Rob,

one of the most basic differences between MSCs and ESCs may not be completely clear; The MSC works by limiting the motor current by adding a series resistor in the current path. This causes loss, which is felt as the resistor(s) getting hot. Hence, the MSC is far from lossless. The ESC operates as a switched regulator; It turns 100% on and off many times (several thousands) a second, and in this way limits the power flowing to the motor. At low power, the on-periods are shorther than the off-periods, and a higher power visa-versa. At full power, the switch is in a fully and un-interrupted on-state. So you will get more run-time on an ESC than you will from a MSC (given that you dont go full power all the time).

At full power there is no real difference between the systems, so the proposed test will not show any difference.

The reasons for almost everybody using ESCs are:

* Better and more linear power control, including braking

* Maintenence free and much more reliable

* Smaller and lighter

* Longer battery run time

Before deciding on which ESC to get, consider how much power you want. If you want loads of power, it's time to go brushless. But the power and speed is likely to cause serious and damaging crashes. You may focus more on relaxed, low-maintenance bashing, and then you can still go a long way with a (couple of) good brushed motor(s). Also, consider using LiPo batteries - they will also take you a step up the power ladder.

A low-turn motor will draw a higher current from a battery of a given voltage. The power equation is P (watts) = U (voltage, battery, more or less constant) x I (current, higher with lower no of turns). So a low turn motor will draw and provide more power, and at the same time rotate (much) faster. You adjust the gearing to match the characteristics of the motor in question. The reason you get more speed, is that you don't gear down quite as much as the rpms go up. This goes for both brushed and bl motors.

Cheers

Mike

[mike_o]

On battery connection:

In series connection, you add the voltages of the batteries connected. You largely maintain the current capacity (if the two batteries are identical). You get twice the internal battery resistance. Actually, a normal 7.2V NiMh battery consists of 6 identical 1.2V cells connected in series.

In parallel connection, you maintain the voltage, but you double the current capacity, and reduce the internal resistance by 50%. Parallelling two batteries is NOT a good idea, though; Unless the two are completely identical and of the exact same voltage, a high current will flow between the batteries, possibly leading to meltdown.

When "parallelling batteries" in dual motored car, I'd strongly suggest to do this via dedicated ECSs or running two separate ESCs on each battery.

cheers

[Rob Buckle]

Mike, great replies that really help. A, erm, 'few' comments

The ESC operates as a switched regulator; It turns 100% on and off many times (several thousands) a second, and in this way limits the power flowing to the motor.

Understood fully the paragraph the above quote is extracted from, but:

1. Why is it that many (all?) ESCs appear to offer reduced power in reverse compared to (full power offered in) forward?

2. One of the differences I've noted between MSCs and ESCs is the 'brake' function. I have experience only of being able to go from fully forward to fully reverse (I appreciate, however, that doing so mistreats the gearbox/motor). I've read a bit about brakes and found this post (and indeed thread) helpful. However, isn't 'shorting' the same as touching the two battery terminals together? Isn't this bad for (and for a Li-Po, disastrous) the battery?

3. From the same post linked to in Q2 above, are we saying that when using an ESC, the act of braking actually returns some power to the battery?In other words recharges it (by a small amount)?!

4. Is it the case that to go from 100% forward to stop (simply by releasing the radio control forward/backward stick) a car with an ESC will come to a complete halt over a significantly shorter distance than a car with an MSC (which presumably is freewheeling with only friction to slow it down?)?

At full power there is no real difference between the systems, so the proposed test will not show any difference.

Hmm, I see what you mean. Will need to think about this a bit more.

Before deciding on which ESC to get, consider how much power you want.

As noted to TWINSET, I intend on taking things slowly, as much to learn about R/C as to arrive at a setup I am happy with. I doubt it's possible for me to read/learn all about R/C and then buy parts that will result in a modded Clod Buster that perfectly fits my needs. There will always be an element of 'suck it and see', an iterative process until the Clod Buster attains a level of performance I am happy with. I must say I am rather looking forward to the journey.

If you want loads of power, it's time to go brushless. But the power and speed is likely to cause serious and damaging crashes.

Ha! You should see the chevy shell of my Clod at present (bit of a wreck)! In a way it's quite good that the existing shell is in poor condition because it frees me from worrying about potentially damaging pristine bodywork etc. and can instead quite happily use it as a (crash) test truck.

You may focus more on relaxed, low-maintenance bashing, and then you can still go a long way with a (couple of) good brushed motor(s).

This sounds exactly where I want to be. At least at this time, I do not expect to be racing competitively. Ultimately I am looking for a Clod Buster that is rapid yet controllable, with 20-30 minutes of run time (preferably the latter). Adopting that setup, or perhaps with a bit more in the way of speed, I aim to build a custom shelf queen Clod Buster.

Also, consider using LiPo batteries - they will also take you a step up the power ladder.

Yup, already decided on that route. See this thread.

...a low turn motor will draw and provide more power, and at the same time rotate (much) faster. You adjust the gearing to match the characteristics of the motor in question. The reason you get more speed, is that you don't gear down quite as much as the rpms go up.

Are we saying that I was correct in my previous post that fewer turns (more speed) is countered by gearing down, but that we gear down by a disproportionate amount compared to the increase in speed from adopting a motor with fewer turns, the net result being less speed than the motor(s) is capable of providing, but still greater speed than a motor with a greater number of turns, and also more torque?

Cheers,

Rob

[Rob Buckle]

Mike,

In series connection, you add the voltages of the batteries connected. You largely maintain the current capacity (if the two batteries are identical). You get twice the internal battery resistance.

So this results in motors turning twice as fast (in the case of two batteries in series)? Do you have to use motors specifically for higher voltages if you plan to do this (not sure I am - sounds like insane (read: uncontrollable) speed ensues)?

With regard to motors, why is it that some (most?) cannot run backwards? In my ignorance I would automatically have assumed that simply by reversing the battery leads to a motor would cause the motor to reverse.

When "parallelling batteries" in dual motored car, I'd strongly suggest to do this via dedicated ECSs or running two separate ESCs on each battery.

Just to clarify, did you mean to end "... two separate ESCs, one to each battery"?

Rob

[TWINSET]

With regard to motors, why is it that some (most?) cannot run backwards? In my ignorance I would automatically have assumed that simply by reversing the battery leads to a motor would cause the motor to reverse.

Most motors can run backwards, provided they don't have a diode across the terminals.

A lot of 'speedy' motors are 'timed' though - this means they run at one speed forwards and a different speed in reverse.

As the rear motor of a Clod runs backwards, if you don't re-time the rear motor it'll be running slower than the front one.

All you need to make sure is that the rear motor is timed back past zero by the same amount as the front one is timed forward of zero (ie +5 at the front = -5 at the rear)

You do still need to reverse wire the motor too - positive wire to negative tab etc.

Obviously, before cracking open the wallet, make sure the motors have adjustable timing, unless you go for zero timed motors.

[Rob Buckle]

A lot of 'speedy' motors are 'timed' though - this means they run at one speed forwards and a different speed in reverse.

What is the reasoning behind this? What's the problem with permitting full speed backwards?

All you need to make sure is that the rear motor is timed back past zero by the same amount as the front one is timed forward of zero (ie +5 at the front = -5 at the rear)

Interesting. So, if I understand rightly (from this article), by using a motor that allows its timing to be adjusted, one can obtain higher rpms over torque or vice versa through adjustment, without having to purchase a new motor?

[TWINSET]

What is the reasoning behind this? What's the problem with permitting full speed backwards?

Interesting. So, if I understand rightly (from this article), by using a motor that allows its timing to be adjusted, one can obtain higher rpms over torque or vice versa through adjustment, without having to purchase a new motor?

It's not so much 'permitting' as taking advantage of how a motor works at the expense of some reverse speed.

Normally, reverse is used to get you out of trouble, the speed at which you do it is only really relevant if you're re-enacting an episode of Starsky and Hutch

Advancing the timing means that you get more speed from the motor - if you were to retard the motor's forward RPM with negative timing, it would go faster in reverse.

Most serious racing doesn't allow the use of reverse, a lot of race ESCs don't even have reverse, and as the faster 540 motors are aimed more at racers, reverse speed isn't that much of a consideration.

There aren't that many vehicles that use a motor on each axle either, so making 'reverse rotation' ones isn't really necessary.

The Clod, Wild Dagger (based trucks) and a few crawlers are about it as far as 'demand' goes

As usual though, gaining more speed thru timing is at the ultimate expense of run time

Just be careful to ask about timing when looking at motors - just because some won't be adjustable, it doesn't necessarily mean they're timed to zero.

You want either two zero timed motors, or two motors with timing adjustable both sides of zero

You can see the timing marks on the motor here (the white lines perpendicular to the end-bell)

[Rob Buckle]

Normally, reverse is used to get you out of trouble, the speed at which you do it is only really relevant if you're re-enacting an episode of Starsky and Hutch

Funny! Oh, the nostalgia.

As usual though, gaining more speed thru timing is at the ultimate expense of run time

And, I gather, wear to the motor's component parts.

Just be careful to ask about timing when looking at motors - just because some won't be adjustable, it doesn't necessarily mean they're timed to zero. You want either two zero timed motors, or two motors with timing adjustable both sides of zero

Got it, thanks.

[mike_o]

A timed motor (advanced commutator timing) will perform better in the "right" direction; more power and better effiency than in the "wrong", reverse direction. Run identically timing advanced motors in a dual, opposite rotating motor truck, and you'll get an imbalace in power to front and rear wheels. And the motor running in the "wrong" direction will run hot. Too hot.

A few manufacturers supply timing advanced motors designed for complementary application. Traxxas uses Titan motors, but I think they will not fit your chassis...

[mike_o]

On running in fast reverse: I just remembered an article printed in a British Auto Magazine some years back, describing a modified (1:1) Rolls Royce. The excentric owner had replaced the original engine with a 1600 hp Rolls Royce Spitfire engine and streched the chassis by a fair amount to fit it. Of all the the incredible spec of this machine, I was most impressed by it's reverse top speed which was specified at more than 200km/h. I don't think it was ever tested :-)

[Rob Buckle]

Folks,

Been reading more about ESCs, motors etc. Found this site excellent (for a newbie). Can anyone explain the concept of stalling with respect to electric motors? I noticed it while reading on this site but don't understand how an electric motor can physically stall (and no explanation was given in the thread in question - a search didn't turn up anything either).

Cheers,

Rob

[mike_o]

Not having read the link, I believe "stalling" refers to a state, where the motor is loaded to a degree where it becomes blocked or stops rotating. Thus the Stall Current is the largest possible flow of current into a motor at a given voltage. The Stall Current will be experienced shortly by the motor, battery and ESC when an RC car is started at full power from a stand still.

[Rob Buckle]

All righty then,

I've been looking at motors speedier than Tamiya Sport Tuned for my Clod. I've refreshed myself with regard to timed motors and understand that to be compatible the motors must be either:

1. Zero timed, or;

2. Re-timeable both sides of zero timing.

I understand from this link that Tamiya Sport Tuned motors sold in Europe are 23 turn. From the same link I also see that Tamiya RZ, TZ and (from a separate search) BZ motors also are 23 turn, albeit they all have significantly greater torque and rpms - which is what makes them appealing to me.

I have read elsewhere on the forum that there is no difference between the TZ and BZ (barring a little sponge cover in the case of the latter) and that the BZ has been used in a Clod. So, can anyone confirm which, if any, motors:

1. Are zero timed;

2. Have adjustable timing;

Also:

3. I have read that Clod gearboxes are very strong and can handle more demanding motors than stock. Can it handle the RZ, TZ, BZ class of motor? In other words will the motor require gearing up/down (not sure which way it'd be - sorry!) or metal gears?

4. If Sport Tuned motors are 23 turn and RZ, TZ and BZ motors are also 23 turn, does that mean my Tamiya TEU-103BK ESC will handle them (my gut says no, given that the latter deliver greater torque and rpm, but I can't find fault with my logic!)

5. How easy it is for someone (me) who has never retimed a motor to do so?! What equipment/tools, if any, are required?

Alternative motor suggestions are very welcome.

Cheers

[carparkthrasher]

Joining the party late on this one but my two pence worth re Clod ESC - I too spent time dabbling with the best way to run my Clod as I wanted better speed out of it but am a big wimp when it comes to soldering and running two motors from one ESC. So I went for the 2 ESC approach and have 19x2 Motors each run by its own Mtroniks ESC and battery. So thats twin battery, twin ESC and twin motor. To connect to the receiver I used a Y lead to join the two ESC leads together, removing the red (I think, check first) from one due to the BEC circuitry only needing to get power for the servo from one battery.

The result is she don't half go! Have run it with 2 8.4V 4500 Mh batteries and its a blast.

CPT

[Rob Buckle]

Thanks CPT,

...I went for the 2 ESC approach and have 19x2 Motors each run by its own Mtroniks ESC and battery. So thats twin battery, twin ESC and twin motor. To connect to the receiver I used a Y lead to join the two ESC leads together, removing the red (I think, check first) from one due to the BEC circuitry only needing to get power for the servo from one battery. The result is she don't half go! Have run it with 2 8.4V 4500 Mh batteries and its a blast.

Interesting solution. Presumably you could do away with twin batteries (halving run time, obviously) by connecting a Deans (say) Y-harness to both ESCs from a single battery?

Isn't your solution significantly more expensive than just using an ESC than can handle the load of two motors, splicing leads for twin motors if necessary if the ESC is sold as single motor only? Just asking, not criticising.

[kaiser]

don't worry about the strength of the cold axles, they can handle motors way hotter then anything tamiya makes.

some guys are running 5700kv brushless systems on 11.1 volts with no issues.

i personally run dual 4000kv (8.5t) brushless systems on a stock (ballraced) gearbox with no issues.

when my clod was in stock trim i ran dual sport tuneds with the teu-103bk, but from what i understand is that the sport tuned motors in north america are 27 turn motors.

the teu-103bk is rated only for 27turn motors IIRC.

[Rob Buckle]

Hey Kaiser,

...when my clod was in stock trim i ran dual sport tuneds with the teu-103bk, but from what i understand is that the sport tuned motors in north america are 27 turn motors.

the teu-103bk is rated only for 27turn motors IIRC.

I've done a bit more digging. The non-European Sport Tuned motors are 27 turn whereas the European (my own) are 23 turn...single wind. The Super Stock RZ, TZ and BZ are seemingly 23 turn double wind which is why they are not compatible with the TEU-103 BK ESC, even though they are all 23 turn motors. See also this.

All,

I've no interest in greater than 7.2v (7.4v really, from LiPo) battery packs and at this time 550 size cans are out. I'm thinking about using a no limit (single motor) ESC and connecting up to twin RZ, TZ or BZ motors in parallel. The no limit ESCs I am considering are the Mtronik RV Max or the Mtronik Storm X. Actually the Storm X appears to me to be the better option even though it is cheaper. Am I missing something? Either of these ESCs will handle 2 number 23 turn motors...which brings me back to motors.

It seems that TZs, at least, are advanced timed. I suspect RZ and BZ must be too. I've found this post, and the couple that follow it, very useful, so I'm thinking of trying my hand at re-timing a pair of BZ motors. Why the BZs? Well, they're seemingly intended for off-road, so should be more applicable for a Clod than either of the other two.

Anyone any thoughts thus far? This is new territory for me and I'm always keen to hear the thoughts of others.

[Jonesy76]

Hey Kaiser,

I've done a bit more digging. The non-European Sport Tuned motors are 27 turn whereas the European (my own) are 23 turn...single wind. The Super Stock RZ, TZ and BZ are seemingly 23 turn double wind which is why they are not compatible with the TEU-103 BK ESC, even though they are all 23 turn motors. See also this.

All,

I've no interest in greater than 7.2v (7.4v really, from LiPo) battery packs and at this time 550 size cans are out. I'm thinking about using a no limit (single motor) ESC and connecting up to twin RZ, TZ or BZ motors in parallel. The no limit ESCs I am considering are the Mtronik RV Max or the Mtronik Storm X. Actually the Storm X appears to me to be the better option even though it is cheaper. Am I missing something? Either of these ESCs will handle 2 number 23 turn motors...which brings me back to motors.

It seems that TZs, at least, are advanced timed. I suspect RZ and BZ must be too. I've found this post, and the couple that follow it, very useful, so I'm thinking of trying my hand at re-timing a pair of BZ motors. Why the BZs? Well, they're seemingly intended for off-road, so should be more applicable for a Clod than either of the other two.

Anyone any thoughts thus far? This is new territory for me and I'm always keen to hear the thoughts of others.

I had the same fun and games with my progression from Blackfoot/MB to the twin motored Clod and TXT-1.

I owned my first Clod about 5 months ago, and about 4 months ago took delivery of my first TXT-1. I sold the Clod soon afterwards but still have the TXT-1 running a few customised bits and bobs along the way.

The Clod I owned was the Super Clodbuster Metallic edition which comes as stock with the TEU103 speed controller so I also have a bit of experience with that too. My happily ran twin Sport Tuned motors that I put in it for a while (one is now in my MB, and one went into my WW2 that I got rid of, as I returned my Clod to stock when I sold) so I know those will work with the TEU103 speed controller, and you'll get somewhere around a 25 minute run time using a 5000mah standard 7.2v nicad.

I also have both TZ and RZ motors at home in my cars, and I haven't seen any timing marks on them (they also go like the clappers backwards when you get your wiring the wrong way round like a numpty!).......I'll check them out more closely when I get home.

As far as my speed control goes when it came to re-building my TXT-1 (see here http://www.tamiyaclub.com/forum/index.php?showtopic=59431 ) I wanted to go for speed, especially as I tend to run my TXT-1 on a beach, rather than crawling with the thing, so it has a pair of LRP 19x2 motors in it for pure speed. The TXT-1 needs that as it's lower geared than the Clod (i.e. a stock TXT-1 on silver cans will be a lot slower than a Clod, but go up more) but twin motor ESC's are bloomin' expensive for the lower turn motors.

My solution was to buy a no-limit Mtroniks ESC from Modelsport, and then wire the motors to it with a home made rig like in the photos on my TXT-1 rebuild page. The wiring loom was simple to make and only needed 6 soldered joints so it should be a piece of cake to create.

This has worked faultlessly for 4 months now, and doesn't get anywhere near overheating even after 2 5000mah batteries (about 18mins on a beach run). To run a similar set-up for a clod you would just have to connect one motor in the opposite direction (the TXT-1 motors both turn in the same direction)