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Author Topic: To Brush or not to Brush  (Read 3290 times)

Ade the Blade

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To Brush or not to Brush
« on: August 30, 2011, 09:16:49 PM »

I have a question that keeps going through my mind as i have not decided which motor to install in my hull, the thing is that i have a good understanding  brushed motors but no idea about brushless so my question is stick with what i know or go brushless and if so why, and are brushed motors dead and buried or still have a place in the world of rc

Regards Ade
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Colin Bishop

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Re: To Brush or not to Brush
« Reply #1 on: August 30, 2011, 09:33:08 PM »

It depends on what sort of boat you have got. For most models brushed motors are perfectly adequate. If you have very high power requirements then you might want to consider brushless with the additional complications that they bring such as specialised speed controllers. Also brushless motors are not too good at low speed response which is not what you want when you have a scale boat.

A lot of people will advocate brushless because they are 'the latest thing'. That doesn't necessarily mean they are better in a particular application. Some people fit brushless when brushed would have been just as good because they think it is the thing to do but in practical terms they might have been better fitting brushed motors at lower cost.

As in all things, do your homework first.

Colin
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MikeA

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Re: To Brush or not to Brush
« Reply #2 on: August 31, 2011, 12:30:08 AM »

is this for the mtb turned yacht boat? with brushless motors they do fast and very fast at that. too fast in most propulsion applications. if you are going to run a surface drive propulsion then by all means brushless is the way, if not then there a pointless expense because they cant run to there full pontential.  i still stand by my original recomendation:

http://www.ebay.co.uk/itm/MFA-TORPEDO-850-ELECTRIC-MOTOR-ESC-P-PACK-MODEL-BOATS-/400233343175?pt=UK_ToysGames_RadioControlled_JN&hash=item5d2fc428c7
 
this will get your boat on a plane. its designed for MTB and yachts inpeticular and will give you a decent run time.  :-))

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nick_75au

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Re: To Brush or not to Brush
« Reply #3 on: August 31, 2011, 06:41:49 AM »

Mad Mike and Colin, you just have to get the right motor for slow.  1000 Kv or so on 6 volts  750 Kv or less on 12 volts, ESC's are no different to brushed ones in availability these days and similarly priced.

The motors can spin slowly enough to count revolutions :-)

Ade if you understand brushed use a brushed motor there is nothing wrong with them.

Nick
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Ade the Blade

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Re: To Brush or not to Brush
« Reply #4 on: August 31, 2011, 08:13:57 AM »

Thanks guys for your replys ,Mike it is for the boat i am converting and the package you have recomened  sounds great, it,s just after reading so many posts on here and boy i have spent a lot of time reading you start to go a little crazy  ie one day i am going brushless the next brushed . As Colin says things like price and the fact that brushless is the new kid on the block makes you think is a top brushed motor still a contender and as good as brushless system sorry to ask this question it,s just i  am not a rich by a long chaulk and would like the best i can afford .

Regades Ade
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MikeA

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Re: To Brush or not to Brush
« Reply #5 on: August 31, 2011, 01:33:07 PM »

here is a cheaper set up but it has a mechanical speed controller which if you havent had experience with them is not worth the hassle.
http://www.ebay.co.uk/itm/MFA-Torpedo-850-Marine-Power-Pack-/130558726495?pt=UK_ToysGames_RadioControlled_JN&hash=item1e65e8115f

i use this 30A esc:
http://www.ebay.co.uk/itm/Turnigy-30A-30amp-BRUSHED-ESC-speed-controller-ukstock-/140594432652?pt=UK_ToysGames_RadioControlled_JN&hash=item20bc14ca8c

its forwards only though and needs your transmitter throttle stick manually adjusting so that full reverse is then nuetral. On my futaba 2ER attack you can open it up and take the spring out and fit a ratchet style throttle which is used in planes. it just take a bit of inginuity with a screw driver.

with a propshaft from MMB you could have the entire drive train fitted for about 70 quid.

if you look towards the bottom of this page youl find some decent 12v batterys with a reasonable weight but cheap.
http://www.component-shop.co.uk/html/large_packs.html
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MikeA

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Re: To Brush or not to Brush
« Reply #6 on: August 31, 2011, 02:02:51 PM »

by no means am i saying that a brushless cant be used but its not cheap youl need  a brushless like this:
http://www.ebay.co.uk/itm/RCS-Model-C5040-890-KV-Outrunner-Brushless-Motor-OM195-/300473860267?pt=UK_ToysGames_RadioControlled_JN&hash=item45f5a340ab
im unsure if this will produce the torque required though

and youl need this esc:
http://www.ebay.co.uk/itm/SEAKING-90A-Water-Cool-Ship-Brushless-Motor-ESC-SL170-/270646249317?pt=UK_ToysGames_RadioControlled_JN&hash=item3f03c60765

see these are cheap ones that work. but thats 70 gone and you havent got 30 of battery and 30-40 of drive train yet. it adds up see. youl will probably need a lipo with a discharge rate like that and youl need a balance charger to charge it and then its getting silly.
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tigertiger

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Re: To Brush or not to Brush
« Reply #7 on: August 31, 2011, 02:17:38 PM »

My crude understanding.
If you want really really fast, then go brush-less. And so for fast electric they are popular.

If you don't want to go fast, then brushed will do the job, better, for less money.

But what do I know.
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Colin Bishop

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Re: To Brush or not to Brush
« Reply #8 on: August 31, 2011, 02:21:42 PM »

Quote
If you don't want to go fast, then brushed will do the job, better, for less money.

Yes, don't buy a Ferrari if you just want to go down to the shops....
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MikeA

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Re: To Brush or not to Brush
« Reply #9 on: August 31, 2011, 04:47:49 PM »

he does want to go fast but in a 3ft perkasa hull. no much point in buying a brushless when only needs a bout 8-10,000 revs which a 900 brushed will do fine. so why pay more for a motor that you only use 1/4 throttle? but this is all my oppinion and if someone else has a better recommendation then touche.  :-))
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Ade the Blade

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Re: To Brush or not to Brush
« Reply #10 on: August 31, 2011, 09:06:02 PM »

Hi Guys you,ve all  have been so helpfull  ,it was just a thought as i am rebuilding a house as well during all of this so cash is a bit tight and the boat will not see the water till spring .But all of your input will help as the nights draw in and i can spend more time on the boat and leave the diy over the winter i may come back to this problem as time goes on so this may not be the last post thanks again.

Regards Ade
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Shipmate60

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Re: To Brush or not to Brush
« Reply #11 on: August 31, 2011, 09:13:24 PM »

Ade,
If you want quite fast AND stability in a perkassa I would highly recommend 2 shafts.
It depends how you want to power her but 2 x 600BB Turbo's on 9.6 or 12 volts will have her going well but these tend to be rather power hungry.

Bob
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Ade the Blade

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Re: To Brush or not to Brush
« Reply #12 on: August 31, 2011, 09:46:24 PM »

Hi Bob i would like a fair turn of speed the hull at the moment is  set up as single prop affair , i have never had a boat that has twin motor,s before and if i went twin i would need a bit more info on how to fit twin shafts into the hull there is a fair amount of room in the hull so this i guess is more than poss. I have given the twin power thing a fair amount of thought but only been put of as i am unsure as to how to arrange this in the hull and can not see any posts on the forum about how to make a single screw into a twin.

Regards Ade
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Shipmate60

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Re: To Brush or not to Brush
« Reply #13 on: August 31, 2011, 10:22:33 PM »

Ade,
The conversion would mean major surgery to the hull.
As it is a 3 ft Perkassa a single shaft with a 700 bb turbo will have her going well BUT you will need a high output Speed Controller and light batteries capable of delivering a fairly high current.
MiNim you do not need LiPo and the associated expense.
There are so many Perkassa's that do not perform very well, unfortunately speed does require cost.
Even 2 x 540 motors will require 1 very high output or 2 high output Speed Controllers and batteries.
The choice is yours.

Bob
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Ade the Blade

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Re: To Brush or not to Brush
« Reply #14 on: September 01, 2011, 08:14:17 AM »

Hi Bob

I will be useing Nicads as they are cheap and i use them in my scale SCX 10 Honcho and Traxxas trucks as i do a fair bit of scale trail driving my other passion plus i have all the chargers as well . Your comments on lipo,s sounds true all a bit Star Trek for a guy of my age and maybe not worth the bother as Nicads are so esay to look after and the hull is big enough to take two 7.2,s with no probs so i think it is going to be a single brushless motor and hope she sails well or at least gets on the plane.

Regards Ade

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nick_75au

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Re: To Brush or not to Brush
« Reply #15 on: September 01, 2011, 08:27:26 AM »

http://www.hobbyking.com/hobbyking/store/__8483__Turnigy_3639_Brushless_Motor_1100kv.html

on 14.4 volts, (2 buggy packs in series) about a 40 mm prop you could go up or down slightly on the Kv.

a 30 -45 amp ESC
Like this

http://www.hobbyking.com/hobbyking/store/__13445__HobbyKing_Brushless_Car_ESC_45A_w_Reverse.html

can handle 12 cell Ni-XX

if you run only 7.2 a 1500-2000 Kv motor but expect shorter run times and a bigger ESC will be required, about 45-60 amp depending on which end of the Kv ratings you pick.

Nick
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Ade the Blade

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Re: To Brush or not to Brush
« Reply #16 on: September 01, 2011, 09:04:07 PM »

Hi Nick

Thanks for your input i see the motor you recomend is used for flight ,can you use these motors for boats as well  it may be a simple question but as i say i have little understanding but learning by the day.

Regards Ade
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sunworksco

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Re: To Brush or not to Brush
« Reply #17 on: September 01, 2011, 10:19:45 PM »

Old traditions are tough to change but everything about brushless makes sense, less battery draw, less audible noise and static interference, small size ,less vibration, better cooling, very slow scale speeds achievable.
 I'm using an eFlite 245kv brushless with a Castle Hydra ESC  in my submarine for scale speeds.
Giovanni
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nick_75au

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Re: To Brush or not to Brush
« Reply #18 on: September 01, 2011, 11:58:35 PM »

They are fine for boats, I use out-runners in all my boats that have brush-less motors. I have a slightly higher Kv motor very similar to the one I linked to in my Ski boat.


Nick
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