Model Boat Mayhem
Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: jim c on March 19, 2019, 03:59:22 pm
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hi can anyone reccommend parts required to swap brushed speed 700 motor and speed controller,to a brushless system motor and speed controller at present have 2 700 /s in a perkasa will i need 2 systems on this boat ,or would1 do? ta very much ,jim c,
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Jim
Although a few people have (allegedly) managed to run two brushless motors from one speed controller, in practical terms you'll need one ESC for each motor. You then have the options of running them both from the same Rx output via a Y-lead; connecting them to LH and RH stick channels to give you "tank steering", or connecting the two ESCs to a rudder/motor mixer. BTW in all cases you'll need to disable the BEC in one of the speed controllers by removing the red wire from its 3-wire Rx connection lead.
I'm not in a position to suggest a particular motor as I haven't had to substitute a brushed Speed 700 yet. You'll also need to specify whether it's the 34" or 46" version of Perkasa.
Dave M
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hi thanks for your reply ,it is a 46" perkasa running on lipo/s sinc using lipo/s i have destroyed 2 fusion aquapower120 speed controllers ,hence hoping to change to brushless, i would prefer to use 2 for better performance, many thanks jim c.
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Hi Jim, I have just done a similar upgrade. I had 2x Graupner 700 motors connected to a single Electronize speed controller, in my Waterjet powered Rib. I replaced these with a pair of Turnigy Aerodrive 3542 1250kv Brushless Motors from Hobbyking, and a pair of Leopard 30A Marine V3 Waterproof Brushless ESC's from Component Shop. Each Motor/ESC has it's own 5000mah Lipo. However these motors may not be the best option for you, since in my setup they are driving 29mm impellers, whereas you will have larger diameter props. I didn't connect the water cooling as the ESC's don't get warm.
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Charlie Dare I suggest something that you might not have thought of......there is nothing to stop the servo rod comming adrift from the servo horn only the grace of god so to speak,if I was you I would take the horn off the servo and put either some heatshrink over the end of the rod or another idea is to cut some outer outer plastic sheath from electrical cable and simply push it on....just dont want to hear of you stranded in the middle of a lake
Dave
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Charlie.....this is a very tidy motor upgrade and I am sure the performance will be marked....
Dave........I agree simple bent wire servo connection are absolutely false security. The DU-BRO range of connector/joints is extensive and also facilitates some micro adjustment
The steel ball & high impact 'plastic' socket has a high mechanical retention rating, however the bronze spherical hollow ball, mechanically constrained in the plastic body is ultimately also further constrained by a bolt back to the servo disk
The latter [two shown] servo to horn spherical attachments provide the highest level of insurance :-)) .....and at a relatively low cost
Derek
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A bent wire link works perfectly well,, what is does need is a keeper or EZ link.an example is https://www.robotbirds.co.uk/default/du-bro-micro-e-z-link-849.html (https://www.robotbirds.co.uk/default/du-bro-micro-e-z-link-849.html)I have a small jet where the linkages all have one of these on end with a clevis on the other.
Jim
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Or just bend the link the other way to create a z-link.
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many thanks to those who replied to my post on fitting a brushlees system in place of a brushed one, but we seem to gone on the topic of servo/s and there links ! can we come back to the problem in hand it is a 46"perkasa on 2 speed 700 turbos and fusio aquapower esc with 50mm racing props ,what motors and esc can you recommend will i have to drop size of props?many thanks ,jim c .
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What pack voltage are you running? The higher voltage you can go the lower the current draw from the battery for equivalent wattage. I would go for minimum 3S, preferably 6S, 22.2volts nominal, as it sounds like a fairly large boat.
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For a boat that size you will need a pair of pretty beefy out runners. A pair of these would do the job
https://hobbyking.com/en_us/turnigy-aerodrive-sk3-5045-660kv-brushless-outrunner-motor.html (https://hobbyking.com/en_us/turnigy-aerodrive-sk3-5045-660kv-brushless-outrunner-motor.html)
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Well you'l certainly have no shortage of power with a pair of those, almost 2hp per motor!
Could get away with something a lot more modest if you only want a modest improvement on the 700's. Do bear in mind to get the best from the motors you will need the batteries that can provide the beans.
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What pack voltage are you running? The higher voltage you can go the lower the current draw from the battery for equivalent wattage. I would go for minimum 3S, preferably 6S, 22.2volts nominal, as it sounds like a fairly large boat.
What do you mean by 'racing props'? Are they meant to run submerged? Lots of 'racing' boats use surface-piercing propellers which are meant to run with the hub of the prop on the surface; running them submerged creates an immense load on the motors without any advantage in thrust. I would honestly try some scale props on your shafts as I think that is what has been causing you to overload your ESCs.
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many thanks for all replies, the batt/s are 3s 5.000 milli amp ,11.2 volts would those run those motors? again many thanks {getting their} jim c.
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hi Jim, i just checked the specs again, and a 4 or 5S Lipo is recommended, so your 3S wouldn't be up to the job. We should be able to find a motor you can use with your 3S battery. Have a browse on Hobbyking and see what's available. Also, have a read through all of the various threads in the Brushless section here on Mayhem, lots of useful advice to be found.
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Hi Jim, check out my post on a 1/12th scale ( 32" ) Huntress I built , the second page will be of more interest to you . . .
https://www.modelboatmayhem.co.uk/forum/index.php/topic,51679.0.html
I also converted an old Swordsman to brushless & lipos . . .
https://www.modelboatmayhem.co.uk/forum/index.php/topic,56327.0.html
The outrunners seem to be the way to go , and the prop size is important as these motors will just keep sucking the amps out of batteries, you need maximum power smallest prop , I use DEANS connectors for the battery , rated to 60amps, tamiya's will just melt .
Also a voltage alarm on each ESC is wise, you need a program card to set up the ESC's ,whatever motor you get should have one available , each maker has a different method of setting .
Go for it Jim , it's a whole new learning curve . . .
Bill