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esc selection help

Old 10-16-2010, 09:47 PM
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cat samich
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Default esc selection help

hey everyone, looking for everyone's input on selecting an esc. im going to be running a neu 1515 2200kv on 6s in a 33" cat similar to the hotr cat. i had decided to find a totally different motor after burning up 2 hydra 120's but then thought what the heck? there has to be an esc out there that wont require taking out a bank loan to afford that will power this boat like id want.


so throw out your opinions, im open to anything
Old 10-18-2010, 04:37 PM
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scullyeng
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Default RE: esc selection help

Turnigy Marine 180A Brushless Boat ESC

http://www.hobbyking.com/hobbyking/s...idProduct=8937
Old 10-18-2010, 05:04 PM
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Default RE: esc selection help

Poor ESC recommendation, no ESC will work. First off, you have a very hot setup for a boat that large, it is really a hydro motor more suited to a 30" hydroplane - ON 4S! There is no ESC that will handle that motor on 6S, you will burn down any of them as you will be drawing well over 200 amps. And never run any ESC at its maximum voltage rating on a 'hot' setup. They will ALL burn down eventually, even the $700 Schulze 40-160, I've seen it happen.

You have two choices. One, run the 1515/1Y on 4S with an m440 or x442 prop and watch for heat. The Turnigy 180 might work for this application.
Two, sell your motor and buy a more appropriate one for 6S - any similarly-sized motor with a Kv from 1250 to 1500 will work. Use an ESC with a voltage rating of at least 8S unless you can control yourself and not use too much prop for "just a little more speed."





.
Old 10-19-2010, 07:59 AM
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Default RE: esc selection help


ORIGINAL: Got RPM

Poor ESC recommendation, no ESC will work. First off, you have a very hot setup for a boat that large, it is really a hydro motor more suited to a 30'' hydroplane - ON 4S! There is no ESC that will handle that motor on 6S, you will burn down any of them as you will be drawing well over 200 amps. And never run any ESC at its maximum voltage rating on a 'hot' setup. They will ALL burn down eventually, even the $700 Schulze 40-160, I've seen it happen.

You have two choices. One, run the 1515/1Y on 4S with an m440 or x442 prop and watch for heat. The Turnigy 180 might work for this application.
Two, sell your motor and buy a more appropriate one for 6S - any similarly-sized motor with a Kv from 1250 to 1500 will work. Use an ESC with a voltage rating of at least 8S unless you can control yourself and not use too much prop for ''just a little more speed.''





.

advice taken, i ordered a leopard 4082 1500kv. i think im going to throw a swordfish 240 or hydra 240 at it on 5s to start and see where i end up. if temps stay good i will try a 6s run. i also ordered some 8mm bullets to connect it all up with thanks guys
Old 10-19-2010, 10:12 AM
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Default RE: esc selection help

With some soldering skill and minor modification, any esc will handle that current easy peasy.
Buy a cheap 30 a Turnigy or something, then buy 6 International Rectifier HEXFets, rated for 300-500 amps, and replace the stock transistors with those puppies. It is a bit of soldering, but its also the most pornographic nazi ESC in the world for less than 100$

Actually, its the most pornographic nazi ESC in the world, period.
I have never ever seen anything RC rated use so hot transistors. But they are avaible.
Old 10-19-2010, 05:12 PM
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cat samich
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Default RE: esc selection help


ORIGINAL: Von Ohain

With some soldering skill and minor modification, any esc will handle that current easy peasy.
Buy a cheap 30 a Turnigy or something, then buy 6 International Rectifier HEXFets, rated for 300-500 amps, and replace the stock transistors with those puppies. It is a bit of soldering, but its also the most pornographic nazi ESC in the world for less than 100$

Actually, its the most pornographic nazi ESC in the world, period.
I have never ever seen anything RC rated use so hot transistors. But they are avaible.



i lol'd until i pee'd my pants when i read and i quote "the most pornographic nazi esc in the world"
any link as to where i can buy these hexfets you speak of? im very good with an iron and always up for a project. if you have any pics id love to see a write up on how to transform an esc into a pornographic boat raping nazi lol
Old 10-19-2010, 05:23 PM
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cat samich
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Default RE: esc selection help

i did a bit of looking around and found this

https://ec.irf.com/v6/en/US/adirect/...IRF2804S-7PPBF

if im reading this right these transistors part#IRF2804S-7PPBF are 320 amp?
im really not sure of what im looking for, any help is appreciated.
Old 10-19-2010, 07:32 PM
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Default RE: esc selection help

Those you found is 320A yep, correct.
You can buy them at any major electronics store.
Examples of online stores is farnell.com or mouser.com
Each ESC has a 3 phase controlled transistor bridge, consisting of 6 groups of transistors.
It might be just 6 transistors, on smaller ESCS. On larger ones, its ususally multiples of 6.
Anyway, what you do is you remove all these stock transistors, and instead you put in one of these, instead of each group.
Of course, you can put 2 or more in parallell of these aswell, to increase max amp to the totally ridicilous.
Allthough its just a matter of 1 to 1 replacement of transistors, i recommend to get some basic understanding of the workings behind it. Find some litterature on 3 phase H-Bridge, to get an overview on how the circuit works.
Its not desperally advanced, just nice to know how its put together before you start working on it.

A most basic introduction can be found here:
http://en.wikipedia.org/wiki/H-bridge
Note the difference between 1 phase and 3 phase bridges. You are looking for the 3 phase one, wich has 6 transistors. Not 4, as the single phase has. Principally, they got a lot in common though, and understanding the single phase first is making it a lot easier to get a grasp on the 3 phase afterwards.
Old 10-19-2010, 08:17 PM
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Default RE: esc selection help

Replacing the FETs on a cheap ESC leaves you with a cheap ESC that is no longer cheap - but which still has the cheap software programming which is not compatible with the new transistors. And the big new FETs that do not fit where the old small FTEs fit on the board - how do you fix that? You will end up with a POS, not a "nazi". (Considering how the Nazis treated Norway I'm surprised at the analogy.)

Please, will the poster of this wonderful idea (von Ohain invented the jet engine) show us photos of his own personally-modified 30 amp ESC which now handles 350 amps? Along with his experience of running it in high-amp FE boats? No? I didn't think so - dream on friend, your lack of experience is showing. This kind of "help" only feeds the egos of the unknowing wannabees.

More Internet BS, don't fall for it.


.
Old 10-19-2010, 09:36 PM
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Von Ohain
 
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Default RE: esc selection help

"Please resist the urge to curse, flame, degrade, insult or embarrass someone in your post."

There is no such thing as software compatibility on transistors.
AND, guess what? Transistors is delivered in differed packagings! :O Marvellous?
you even get high power transistors as surface mounted! Obviously, those high power escs do have surface mounted fets (doh!).
And on that blatant personal attack and show of incompetence on your side, im ending my part on whats looking to be a less constructive debate, just ass fast as it started.
Hint: Dont argue with an engineer, its like wrestling with a pig. The pig is stronger, everyone gets dirty, and the pig enjoys it.
I got no idea what you are, but something tells me than an electric engineer wont speak of software compatibility on transistors, so obviously you arent one!
Old 10-19-2010, 09:45 PM
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Default RE: esc selection help

Being Polish I have serious doubts about the IQ of anybody who equates anything good with nazis! What's the next post Jewish jokes?
Old 10-20-2010, 06:45 AM
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Default RE: esc selection help

"Please resist the urge to curse, flame, degrade, insult or embarrass someone in your post."

Seems like it cant be repeated often enough?
Since i got IQ enough to understand the rules of this forum, thats all i have to say.
Old 10-20-2010, 07:15 AM
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Default RE: esc selection help

So who's going to post a write up on the ESC upgrade?  Anyone even going to try?

You spoke of 3 phase and 1 phase.  Does this mean brushed motors (1 phase) and brushless (3 phase) because I have some monster 800 brushed motors I'd like to use (maybe even as a power wheel upgrade) but no one makes a decent brushed ESC with big amp output.
Old 10-20-2010, 07:27 AM
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Von Ohain
 
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Default RE: esc selection help

I got a few blown ESCs, so i am going to try a transistor swap on some of these.
I got a lot of schoolwork to do these times, so i cant guarantee for the speed of the progress on the project, but i will have a crack at it, and i keep you guys updated.

A brushed ESC is even sinpler. If it goes both directions (it has reverse) It is likely that its a single phase H bridge.
If it goes only forward, its likely that is has just one single transistor, making it the easiest one of all to upgrade.
And yes, you can swap the transistor(s) here aswell.
Old 10-20-2010, 08:35 AM
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cat samich
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Default RE: esc selection help

wow this turned into a poo storm quick, instead of flaming and telling people that nothing is possible lets think outside the box and see what can be made of it. von do you have any pictures of an esc you have transformed? i was thinking that if i tryed this it would be more of like a aquastar 120 i would start out with. not a turnigy 30 amp
Old 10-20-2010, 09:02 AM
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Default RE: esc selection help

I got no pictures of a finished esc, since i have just started the project.
I do however have a crude schematic over the h-bridge of a Turnigy Plush 100A, since thats the one im going to swap transistors on. But since you are doing a different esc, you will have to do that work for yourself anyway.
I have also put down some thoughts in how to fit the transistors with respect to space requirements, cooling and wiring.
And so far, i have found out that FETs with insulated back plate packing, or similar is probably our best bet
So the TO-220 wich you found is probably not so well suited. You can use them, but you would have to insulate it electrically from its heat sink, otherwise it would short wut with the other transistors through the heat sink.
A better suited packing i think is the TO-247, wich has insulated mounting plate.
One example of TO247 fets is this one:
http://no.farnell.com/international-...7ac/dp/1684527
Rated for 350A. Should be plentyful.
You can of course do 1 to 1 replacement with surface mounted FETs, but the connections is tiny and the soldering is a pain.
So i landed on transistors wich have insulated cooling plate. Making it simpler to cool them all with a common heat sink. I also landed on the thought to put them on a separate printed circtuit board (PCB).
This will require 11 wires to be connected between the ESC, and the new printed circuit. That should be doable.
Those 11 wires is 2 for battery power, 6 for transistor gate control and 3 for motor wires (you still need them down to the old ESC, even though you use new transistors. Because the old PCB is still doing the job om timing the transistors, wich it needs backemf to do).
None of these 11 wires has to be high power wires, so making them into a small, neat and compact cable is no problem.
Old 10-20-2010, 05:46 PM
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Default RE: esc selection help

Hint: Dont argue with an engineer, its like wrestling with a pig.
I am an engineer, and I am also sick and tired of EE wannabes on numerous boards telling us how easy it is to ghetto-rig a cheap ESC to get super performance. I have heard it all before, and in every case nothing ever comes of it. Why? Because it is not as easy as the wannabes think. I have friends who design ESCs for Schulze, etc. and if it was as easy as von-engineer thinks then everyone would have super-powered ESCs. Guess why they do not? It ain't easy, no matter what Wikipedia says. Why doesn't Schulze have a 350-amp controller that works? They can't even get their 200 amp version to be reliable - due to the software.

The software is what makes or breaks an ESC, particularly a high amp one. Believe it. Change the basic structure and performance envelope and the software (designed for minimum performance) won't work. But go ahead, show us your stuff. I'm patient and can wait as long as it takes you to embarrass yourself. But I fully expect this project to fade away just like all the others did when the wannabes found out it can't be done.



.
Old 10-20-2010, 07:31 PM
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Default RE: esc selection help


ORIGINAL: Got RPM

I am an engineer, and I am also sick and tired of EE wannabes on numerous boards telling us how easy it is to ghetto-rig a cheap ESC to get super performance. I have heard it all before, and in every case nothing ever comes of it. Why? Because it is not as easy as the wannabes think. I have friends who design ESCs for Schulze, etc. and if it was as easy as von-engineer thinks then everyone would have super-powered ESCs. Guess why they do not? It ain't easy, no matter what Wikipedia says. Why doesn't Schulze have a 350-amp controller that works? They can't even get their 200 amp version to be reliable - due to the software.

The software is what makes or breaks an ESC, particularly a high amp one. Believe it. Change the basic structure and performance envelope and the software (designed for minimum performance) won't work. But go ahead, show us your stuff. I'm patient and can wait as long as it takes you to embarrass yourself. But I fully expect this project to fade away just like all the others did when the wannabes found out it can't be done.



.
Well I am a jack of ALL trades and master of NONE! but the king of bull ****.

anyhow, you constructive criticism is more then welcome, no one of us is as smart as all of us. . . your wanna be comments are unnecessary.

I personally would like to know more about this software. I have a hard time understanding how a transistor chip might contain software at all. I do understand that software is what controls the transistor via another chip, but fail to understand why using a larger higher amp transistor would cause a melt down? (I am thinking mostly of brushed ESC's forward and reverse)

You make very good points.

Old 10-20-2010, 09:51 PM
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cat samich
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Default RE: esc selection help

lets get back on topic, i have an r2 33.5 cat. i bought a 1500kv leopard 4082. i plan to run anything from 4 to 6s. will a 120 amp hydra or aquastar work or do i need 180 to 240 amp capacity? honestly im not that worried about just buying a controller. at this point i just need some advice from anyone running one of these motors in a 30 or so inch cat on 6s. while i can afford to shell out a couple bucks for an esc i dont want to buy one only to burn it up and have to buy another right away.

reworking a cheap esc sounds fun but also sounds unpractical, labor intensive, unproven, and its just easier at this point to buy one
Old 10-21-2010, 04:22 AM
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Von Ohain
 
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Default RE: esc selection help

Got RPM, nobody is forcing you to read nor reply here.
I refuse to go in any debate on such low level as you are asking for here, and therefore Im not replying directly to anything you say.
Im just saying that leave us alone with our "bull****", nobody is asking you to take part in it.
Personally, Im not taking anyl advice from someone talking about "software compatibility" in transistors, your opinions is worthless right here and right now. I know better myself, this is my profession and my study. Leave me alone.
Im not ****ting in your backgarden, you dont have to **** in mine.

When everyone around you is idiots, and you are the only one doing it right, its time to sit down and think a little.
The reasons projects around you is fading away is obvious, isnt it?
It doesnt matter if its a failure or a success, either way the people behind the project is better off by not sharing their work with guys like you.
If its a failure, they get embarrassed, so they wont share a thing.
If its a success, then why the hell should their share their work with someone whos been nothing but trouble for them in the past?
Think about it. No wonder you never hear them again, the way you treat them.
And you are right, thats exactly the same that will happend here, for exactly those reasons i mentioned.
if i fail, i got no interest of yet another "less intelligent" post from you.
And if i succeed, i got no interest in sharing my work with someone who cant even be polite when they talk to me.
Just leave, go bother someone else.
Old 10-21-2010, 07:20 AM
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Default RE: esc selection help

td(on) Turn-On Delay Time ––– 59 ––– ns
tr Rise Time ––– 370 –––
td(off) Turn-Off Delay Time ––– 160 –––
tf Fall Time ––– 190 –––
First fet listed above

td(on) Turn-On Delay Time ––– 16 –––
tr Rise Time ––– 160 –––
td(off) Turn-Off Delay Time ––– 40 –––
tf Fall Time ––– 57
second fet from IR same amperage

the first one takes 427ns to turn on the second takes 176 ns. If the microcontroller is programmed to use the on and off time values of the above fet and you replace it with the second fet with very different on and off times the controller will be trying to turn on one fet while the one before it is still on and drawing current. 2 fets conducting at once will overheat the motor because you have both of those windings carrying current it shouldn`t be at that time. So software compatability is a major factor in the design of an esc. Basically all the controller is doing is turning fets on and off, it couldn,t care if less the fets should actually be turned on it's just doing what it's told to do. Change the values of the fet you have to change the software.
Both of those fets listed above will only sink that current at 10 V and 25 degrees C and dissipate a maximum of 330 watts. The numbers at 100 degrees are half that!
So how many do you want to run in series and parralel to get the voltage and power dissipation you actually think you'll get? Read the data sheets! they tell you all about the electrical characteristics of the part!
Take a look at a jeti spin 300 amp esc, it can handle 17700 watts, has about a 2" thick stack of fet boards and costs 657$
Not saying someone can't do this project from scratch, you just have to actually know what your talking about! Claiming you can just solder a bunch of fets on a 18 amp esc and have it work! LOL Maybe if you had the ability to re program the esc but I doubt they will give you the base code to modify. You can get a full hex dump from a controller then by hand convert it back to assembler......
These were just the first problems I saw when I checked the data sheets of high amperage fets.
Oh ya did I mention that the fets should be matched?
Oh ya the other thing not mentioned is the fact you need to use logic level gates, the are being controlled by a microcontroller putting out logic levels, The above fet von buddy there thinks will work are not logic level fets! You would have to build another circuit that takes logic level and boosts it to the proper voltage to allow the fet to turn on! Could do this with a couple small transistors, but you have now introduced more latency into the switching circuit.
To put it bluntly if it was easy and reliable Castle or any number of companies would have already put something out there that can take that kind of power, there is a market for it out there, do you not think they have people looking into this? Pay X$ and get an esc you can do anything too including arc welding!
As I posted above the only esc around that has these kind of numbers is 657$ and is huge!
Ignorance is bliss!
Still want to play? By the way I used to design microcontroller gate boards for medical lab equipment! I have a ton of experience setting up pwm for the conveyer drive systems. And code in 8052 assembler as well as PicMicro assembler, comes with the degree in computer sciences.
As I said these are just the glaring issues that hit me during my morning coffee. Couldn't be bother doing any more research into this, read 2 datasheets they gave me all the info I needed. You can argue with the numbers all you want they really don't care, they will do whatever they are supposed to do no matter how much you wish otherwise.
The number don't lie. This is not a simple pull this off and solder this on project.
Old 10-21-2010, 08:29 AM
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Default RE: esc selection help

Husky,  Thank you for shedding some light on the subject with FACTS.

Cat Sandwitch. . . J/K  back on topic.  The Leopard 4082 says it has a PEAK wattage over 3500 watts, at 3500 watts and 22.2V that is 158 Amps.

That number will go up if you drop the voltage, but only if you are demanding that power from the motor. (by propping up)

So asuming you set up your boat and choose the best prop running on 6s, you should go with an ESC over 160A.  If it where me, I would go with a 180A ESC.  That should give you lots of head room.

The constant rated power output from that motor on 6s would be closer to 90amps, but can peak up to 158amps "or more" as they state.

With that motor on a 180a ESC and 6s you will have a cool running super efficient boat.
Old 10-21-2010, 11:01 AM
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Default RE: esc selection help


ORIGINAL: NobodyFamous

Husky, Thank you for shedding some light on the subject with FACTS.

Cat Sandwitch. . . J/K back on topic. The Leopard 4082 says it has a PEAK wattage over 3500 watts, at 3500 watts and 22.2V that is 158 Amps.

That number will go up if you drop the voltage, but only if you are demanding that power from the motor. (by propping up)

So asuming you set up your boat and choose the best prop running on 6s, you should go with an ESC over 160A. If it where me, I would go with a 180A ESC. That should give you lots of head room.

The constant rated power output from that motor on 6s would be closer to 90amps, but can peak up to 158amps ''or more'' as they state.

With that motor on a 180a ESC and 6s you will have a cool running super efficient boat.


thank you sir, finally a straight answer lol. my biggest problem is that i dont know the formulas to calculate all the numbers to figure out what the motor will pull. im going to give myself tons of head room and pick up an aquastar 240 or a swordfish 240

thanks for the help guys
Old 10-21-2010, 01:11 PM
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Default RE: esc selection help

Thanks for some constructive input! I give you credits for that.
Well observed
I have thought about this, and the switch frequency of the Plush is 8 kHz, meaning that it turns on and off again within 0.125mS. (1S/8000Hz = 0.000125S = 0.125mS).
Meaning that the transistor is still fast enough by a huge margin, despite being significantly slower than one rated for a smaller current.
Actually, the slower transistor is still fast enough to turn on and off almost 30 times faster than the Turnigy Plush 100A will be calling for:
(0.125ms/427nS = 0.000125S/0.000000427S=29.3)

So in other words, this isnt a problem.
But well observed, it could potentially been a problem, if it wasnt given a thought before selection of transistors.

And even if you were to select superslow transistors, the problem could still be patched by simply altering the switch frequency of the ESC. This would in practice mean that the ESC would not be able to spin multi-pole motors very fast.
But then again, the large motors isnt fast spinners, so its not really a problem.

But lets say, for the sake of the discussion, that this also fail and 2 transistors is on when they shouldnt:
the motor would still not overheat. Actually, this would lessen the load on the motor, because the transistors would then short with each other. (Look on my link to the H-Bridge explained on wikipedia, and this is explained in detail there).
But the transistors themselves is capable on hundreds of watts each dissipated in heat, so this wouldnt result in anything much worse than a hot ESC. The problem had to be extremely severe for the transistors to actually short out so badly that they torched themselves. Again, Look at the H-Bridge link for an explaination to why. Its no point i do that explaination here when its already written elsewhere.

And as for rewriting the code, whats the problem?
I got all the equippment to program my own Atmel AVR microcontrollers from scratch, I got all the training i need for doing so at school, and should I run into problems, I could always ask my professors for some input. they got background from companies like Voith Hydro, Atmel and Siemens. Aka, guys making power controls for power plants (around 6000 amps), electric trains (around 1500 amps) All using H bridges and semiconductors.

I really dont understand why you are so presistent on "making it impossible". It isnt. Its easy. Even making a ESC from scratch is easy. If YOU think its hard doesnt mean you have to rain on my parade. You can just stop reading here. Nobody forces you.
And Husky, on transistor selection, I had simply taken one and used as an example for a possible FET, I never said that was THE FINAL selection.
Afterall, Im the electrical engineer student here, YOU are the hobbyist. Its quite rude of YOU, as an amateur, to come here and draw my qompetence into question, when you yourself dont even know how a H-Bridge works! (clearly you dont, since you think that slow switch times will cause overload on the motor).

Im still up for a CONSTRUCTIVE debate, but even if you have resorted to using somewhat constructive arguments, your personal motive is still not to contribute constructively. Your personal motive is to rain on my parade, and i dont think thats constructive at all, despite being camouflaged behind constructive points.
Old 10-21-2010, 02:36 PM
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Default RE: esc selection help

240 is super over kill.  I'd say the 180 is over kill.

Real quick for you.  .  Watts = Volts x Amps

The motor is what will ultimately draw as many amps as it wants, so start there.

Your motor's supper huge ultimate power output is rated at 3500watts

In a chart this means

2s (7.4V) x  472.97 = 3500 watts
3s (11.1V) x 315.31 = 3500 watts
4s (14.8V) x 236.48A = 3500 watts
6s (22.2V) x 157.65A = 3500 watts

Now given that you can put out 3500 watts at only 2s 7.4V the size of the wires required to handle almost 500 amps would be huge, and all efficiency would be lost.  You would also have to swing such a huge prop because RPM would be so slow.  It can be done though.

A quick guide.
Watts is equal to Horse Power, in the sense that it is a measurement of power.  Power is what moves the boat (well work is. . .)
1 HP = 745 Watts

Watts = Volts x Amps, so no matter how you move electricity, via amps or volts, the combined output is the watts.

it is easier to move electricity in the form of volts, less loss occurs.

As for RPM, 30,000 is the goal.  So your motor spinning at 15,000 RPM/V (1500Kv) will turn 33,300 RPM  Just right. (these are all unloaded RPM)

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