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Author Topic: Brushless outrunner suggestions for big tugboat  (Read 4892 times)

tsenecal

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Re: Brushless outrunner suggestions for big tugboat
« Reply #25 on: March 30, 2017, 05:24:13 AM »


Thanks for the information.  I'm glad to have someone who tested brushless in a tugboat!


50-80 that's big!  Why would you lower the kv?  1800rpm looks very reasonable to me.  My props have quite a lot of pitch.  With my current brushed set-up I have around 1250rpm.  I tried the the same motors on 12v (2500 rpm) and is was wayyyy overpowered.  The motors overheated.  My goal is to have a little more power with the brushless.  I found a Aerodrive SK3 320kv at HobbyKing.  I feel like it would do the job at 1920rpm.

There it is:

http://sylvainrioux.zenfolio.com/img/s6/v138/p1324013757-4.jpg

one big difference between brushed and brushless motors is that brushless motors do not slow down under load.  your 1250 unloaded rpm for your brushed motor is probably closer to 1000 rpm when the boat is being pushed around in the water.  the 1800 rpm of the brushless motors will be more like 1750 rpm under load.  you will be happy with brushless outrunners that run the props at 1400 rpm unloaded.

this phenomenon is due somewhat to the slightly larger amount of torque the brushless motors have, but mostly to how the brushless ESCs operate.
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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #26 on: March 30, 2017, 05:27:42 PM »

That's great information, thanks a lot!


Since it will be a direct drive set-up I wonder if they will slow down a little more than 50rpm?
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tsenecal

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Re: Brushless outrunner suggestions for big tugboat
« Reply #27 on: March 30, 2017, 06:22:28 PM »

That's great information, thanks a lot!


Since it will be a direct drive set-up I wonder if they will slow down a little more than 50rpm?


nope. my knowledge is limited to what i see, no electronics theory here, but to me, all the magic is in how the speed control feeds electricity to the motor.  if you ask for 1200rpm, its going to do everything it can to give you 1200rpm.   you will either get 1200rpm or you will get smoke.   really good speed controls will refuse to kill themselves, so instead of smoke you will get nothing,  analogous to tripping a circuit breaker.   cheap chinese speed controls will probably give you smoke if you ask too much of them.

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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #28 on: March 31, 2017, 01:36:23 AM »

Understood.  I don't want smoke  :-))
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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #29 on: March 31, 2017, 03:03:15 AM »

One more question.  What is the deal with the programming card? Is it possible to program the esc without it or do I need that card absolutely?
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tsenecal

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Re: Brushless outrunner suggestions for big tugboat
« Reply #30 on: March 31, 2017, 03:51:13 AM »

that depends on the card and the speed control.  some of the cheaper speed controls offer no programability, so no card, others offer more programability if you use the card instead of the throttle stick on the radio.  some are so convoluted to program using the throttle that you will lose your mind if you don't use the card.

my preferred speed controls don't use cards, but the manufacturer has windows software that allows you to program even more features than a card does.

i use the castle creations mamba micro or sidewinder micro for any scale model i care about.  they are much more expensive than the speed controls you can buy at hobbyking, but i feel they are well worth it.  (you can find the sidewinder micro for $50 to $55)  to use the software, you need to get a special usb adapter that plugs into the speed controller.  ($20)  I like them because you can do all kinds of things like set an exponential curve to the throttle, allowing for a low speed bias, with the throttle stick being more sensitive towards neutral.  you can also set them to have no "stutter" between forward and reverse.  lastly, if your motor spins too fast at maximum speed, you can reduce the actual output to a percentage of true potential in single digit increments (so, if 90% of true output is what you want, 90% of true maximum can be set)  because i have model submarines that in real life run extremely slow, i have used the speed control to use only 30% of the maximum power....  another way to limit your maximum rpm at the prop.

if you do buy a cheap speed control that offers programming via a card, the cards are generally less than $10, which makes them better to have than not have.
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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #31 on: March 31, 2017, 12:38:20 PM »

Big thanks again for your help.


Would you consider this one to be cheap?  That's the one I was thinking about.


https://hobbyking.com/en_us/turnigy-brushless-esc-60a-w-reverse-prog-v2-2.html




I can't find what's the max amp rating of the Castle Creation Sidewinder Micro?
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jaymac

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Re: Brushless outrunner suggestions for big tugboat
« Reply #32 on: March 31, 2017, 03:48:45 PM »

This is the card for it and  check the postage  as it is in HongKong
[/size]https://hobbyking.com/en_us/turnigy-speed-controller-programming-card.html
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tsenecal

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Re: Brushless outrunner suggestions for big tugboat
« Reply #33 on: March 31, 2017, 04:32:40 PM »

yes...  even though it is over $40, you can tell it is "cheap" by the fact that its associated programmer only allows you to alter 3 settings.  and it mentions nothing about having a "stutter" to go from forward to reverse, which generally means that it has this functionality.


the "stutter" is what i describe as some sort of hindrance that the speed controller invokes to keep you from going directly into reverse.  either having to press reverse twice, or sit in neutral for a predetermined fraction of a second.  this is something that helps protect gearboxes in cars, but doesn't help in any way for boats.


most car speed controls that offer this label it as something like "rock-crawler" mode.


the castle creations speed controls allow you to enable or disable neutral "stutter" functionality using the software.
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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #34 on: March 31, 2017, 05:46:58 PM »

Very instructive again, thanks.


Is that the one you are using?  I can't find how many amps it can handle?



http://www.castlecreations.com/en/sidewinder-micro/sidewinder-micro-2-esc-010-0150-00


I do have that stutter thing on a Mtroniks Viper Marine ESC (brushed) and I hate that.  I want to make sure I can disable that function.


Thanks jaymac for the link.
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tsenecal

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Re: Brushless outrunner suggestions for big tugboat
« Reply #35 on: March 31, 2017, 08:32:32 PM »

yes, that is the model i use for the vast majority of my model boats and subs... i believe i have 14 of them now.  you will never find an official quote from castle creations on how many amps the speed control will handle, but most educated users claim it will handle 25 - 30 amps.  as i said earlier, my 4 foot tugboat with 6v SLA draws less than 2 amps per motor.  another note that my not have been stated earlier in this thread is that you need a single speed controller for each motor.  in brushless setups, you cannot share a single speed control across multiple motors.

the other CC speed control i own several of (6 or so) is the mamba micro.

the only real difference between the CC sidewinder micro and the CC mamba micro pro boils down to these:
1) new mamba micro X can support sensored motors.
2) mamba micro has heat sinks on the FETs, it can handle slightly more amps +5 over the sidewinder micro...  if that small difference in amp rating makes the difference between you buying the mamba micro or the sidewinder micro, you are probably going to want to use the full size sidewinder instead.
3) new mamba micro X has an auxiliary second channel that can be used for things like altering the max rpm setting.  nice in theory, but basically useless in real world usage.


for anything over 30 amps, i basically use the "cheap" chinese speed controls, they are either for cars or fast (50+ mph) speed boats, so going for a 200amp speed control that might last two seasons before dying, makes me look for something that can be replaced affordably.
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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #36 on: March 31, 2017, 10:50:37 PM »

Thanks, this is very appreciated.


The specs for the motor I'm looking for states that the max amp is 65A.  It feels pretty high to me.  I'm pretty sure I'll never reach that but.... Do you think the Sidewinder micro could handle it?  Or maybe I should go with the full size Sidewinder?  Do they have a protection for overheating or too high currents?


I always use one esc per motor on all of my boats so that's not a problem for me.
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unbuiltnautilus

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Re: Brushless outrunner suggestions for big tugboat
« Reply #37 on: April 01, 2017, 01:59:24 AM »

This is the main problem we, as boat modellers, face. 65 Amps requires a large speed control, but that is probably turning a 14" aircraft prop at something between 14 and 20 volts. We are hardly pushing these motors at all, as detailed above. So we have to reconcile the use of a small speed control on a potentially big current motor. This is the stumbling block where many modellers who are used to 'old school' thinking fall over. Not helped by motor suppliers skewing their data towards the peak performance capabilities of their motors.
Which puts us either into the hands of the slavish specification followers, or those willing to take the plunge and find out through trial and error. I know whose opinions I value.


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tsenecal

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Re: Brushless outrunner suggestions for big tugboat
« Reply #38 on: April 01, 2017, 02:24:16 AM »

desktoprover, i agree completely with unbuiltnautilus...  the specs regarding the 65amp max that the motor is rated at are more like the boundaries...  do not exceed 65 amps at 6s (42 volts)  which can be better stated as 2700 watts.  if you try to push more than 2700 watts through that motor, it will let out the smoke.  there is nothing we can do on purpose with a 4 foot long tugboat that would draw more than 10 amps with a 6v SLA, and if we are smart, we will put a 20 amp fuse between the speed control and the battery, just to make absolutely sure.
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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #39 on: April 01, 2017, 12:07:14 PM »

That makes perfect sense.  Thanks a lot to both of you.  I'm sure this thread will be very informative for others to refer to in the future.
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Tug Fanatic

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Re: Brushless outrunner suggestions for big tugboat
« Reply #40 on: April 03, 2017, 08:57:22 AM »


desktoprover, i agree completely with unbuiltnautilus...  the specs regarding the 65amp max that the motor is rated at are more like the boundaries...  do not exceed 65 amps at 6s (42 volts)  which can be better stated as 2700 watts.  if you try to push more than 2700 watts through that motor, it will let out the smoke.  there is nothing we can do on purpose with a 4 foot long tugboat that would draw more than 10 amps with a 6v SLA, and if we are smart, we will put a 20 amp fuse between the speed control and the battery, just to make absolutely sure.


All perfectly true unless you get a rope or something tied around the prop where suddenly those high load amps start to apply. It then becomes a matter of what gets destroyed first. It might be the battery, the wiring or the controller, so you need put a fuse after the battery.
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Netleyned

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Re: Brushless outrunner suggestions for big tugboat
« Reply #41 on: April 03, 2017, 09:39:33 AM »

6S is more like 22v surely.


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desktoprover

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Re: Brushless outrunner suggestions for big tugboat
« Reply #42 on: April 03, 2017, 05:20:30 PM »


All perfectly true unless you get a rope or something tied around the prop where suddenly those high load amps start to apply. It then becomes a matter of what gets destroyed first. It might be the battery, the wiring or the controller, so you need put a fuse after the battery.


Using a fuse between the esc and battery is always a good idea.
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