Reilly4

Hi Guys,
I am from Melbourne Australia, and new to this site but have been building model boats since childhood. These are mainly electric but have also helped a friend over the years with re-building/supporting his glow engined boats.

I am new to the electric speed controllers, having used the variable resistor boards for my ships and 6/12 volt switchers for the faster patrol boats. I will put photos of the boats in my profile shortly.

I have bought a speed controller branded a Himark HI015. It is good for 50 amps forward or 20 reverse. Its working voltage is 5-10 cells (6-12 volts). It looks remarkably like the Proboat item photographed in the PT boat on this site that has 3 of them.

I am building a Fairmile D 1/24 scale. I intend to use 2 Graupner 700BB motors in parallel with the single speed controller.

My question is this.
Can I disable the BEC part of this controller and use it with separate power for the engines and separate power for the RC. Although I have Futaba RC sets that are PCM FM, they do not have the newer BEC capability.

I have copied the basic instruction sheet and a photo of the ESC.

Thanks

patmat

Maybe I'm confused about what you need to do, but you don't need BEC on the Rx to use the ESC's BEC.

The logic circuits in both ESC and Rx need about 5v (4.8 - 6.0v battery pack will do).
Some Rx's have "BEC"... merely means it has an internal voltage regulator that allows you to plug in a lead directly from your main pack (7.2v? 8.4v? etc); the regulator makes 5v and sends that to the Rx brain, and on to the servos as well.

But most ESC's do the same thing... as as long as they're regulating 5v out of the main pack, and as long as the ESC already has a lead going to the Rx with signal and ground, why not just send some of that 5 volts up the red wire back into the Rx?

So... for BEC or non-BEC Rx's, just connect that BEC-enabled ESC to the Rx, and away you go.

Now, should you prefer to use a separate pack for your Rx (either a 4.8-6v Rx pack, or any higher V pack into a BEC-Rx), it's common to disconnect the 5v lead out of the ESC. You can just snip the red wire (crude), or use a sharp little tool to unhook the 5v lead out of the plastic shell, and tape it back... so that you can use BEC later should you change your mind. That's all there is to it.

Pat M

mfr02

Patmat is right. To unhook the red wire, look at the plug. There will be three slots. Gently depress the locking tab that is retaining the red wire pin, and ease the pin out. Tape it back in a tidy manner, and it can be re-inserted later it needed.

Reilly4

Thanks Patmat and mfr02,
I originally asked at the hobby shop where I bought this ESC and was told that there was no way out, and that it would be best to use the BEC circuitry and perhaps buy a new receiver.
Not being satisfied with that answer I decided to investigate further and have found this website and forum. I have read a similar post about disconnecting the red wire, and decided to ask for help as I am impressed by the knowledge and help offered.

I am to understand then that the red wire can be a two way route. I know how to carefully remove the red wire connector from this plug.

My reasoning to use a separate power supply for the Rx is that I would maintain control of the boat despite the reduction of the voltage of the main batteries for the engines, and that the power to the radio would not be cut off. The weight of the Rx battery pack will not be noticed in this model.

The final question is whether this one ESC is OK for the two Graupner 700BB motors in parallel.

Thanks again for you help

Reilly4

patmat

I've often wondered about that line of reasoning for a separate Rx pack:
1. If you're using, say, 7.2v packs or higher, a "low" battery will still have plenty of juice to supply 5v and a few milliamps to the Rx;
2. And if the main pack is down that low, what good is radio control? You won't have anything to command!

I always just use the BEC; it's a good thing.

Two 700's on one of those ESCs? Good luck. Most ESCs are not capable of delivering the advertised current. Buy one more now for a total of two, vs. toasting one and buying a total of three!

Pat M

patmat

But also check out this thread for water cooling your ESC- he seems to be running a pair of 700's on one...

http://www.rcgroups.com/forums/showthread.php?t=758811

PM

Reilly4

Thanks Pat for all the useful info and link.

The ESC in question looks identical to mine, and in Australia too. I should probably buy another and watercool both.

I have previously used 2 x 6v x 7.2 Amp hour gel cells in series successfully with my other patrol boat that has 2 x Mabuchi 550s, so I was going to start with them, but also try some 5ah NiMH D cells as an alternative. It will be 12v with as many Amp hours that I can get to fit into the hull for the right weight.

I shall post some photos of some of my ships soon.

hansvonpensch

I ran 2 "12v" Graupner 700s NOT 8.4v or 9.6v (that would make a difference) in parrellal on 9 cells. 10.8 volts turning (2) 1-3/4" 2" pitch 3 blade brass dumas props. with a proboat esc 50 amp rating it looks like the one in your photo. I ran (8) 150' passes at FULL speed, I ran it hard, maby 13 mph in a dumas trojan I checked the esc and I could hold as long as I wanted. 5 minutes would have been possible, it beat the 5 second rule. but it was warm.

hansvonpensch

They are 12v BB turbos, I do use the bec but was told if I elimated it by plugging in a seperate battery into the reciever and not turning on the proboats switch, it could only run better.

Umi_Ryuzuki

A BEC is typically not designed to supply more than one amp to the radio system.
If there are a lot of servos,... (More than two) and features that run off of the reciever power, the
BEC can be overwhelmed, and cause the entire system to get the jitters.

When I run combat, it is always nice to still have control of the guns if your boat should die on the pond.
I may not be able to run away, but I can defend myself, or the tow while being pushed back to safe harbor.

(I have actually had the battery connector shot off the battery... Lousy allie tactic in my opinion...) [:'(]

I usually cut the BEC switch off, and solder a small deans plug in its place.
That way the switch doesn't accidentely get turned on, and I can plug the switch back in
should I ever want to use the BEC.

Reilly4

Thanks Hansvonpensch and Umi_Ryuzuki

My motors are 2 x 12v 700BB. The proposed props are Graupner 40mm 2 blade standard pitch (RH & LH)

I just bought another ESC of the same type so that I have one for each motor, connected through a 'Y' harness but with the red wire removed from the connector to eliminate the BEC.
The plan is to water cool both the motors (aluminium coil) and ESC's.

I am not sure how many servos will be used on this boat at this stage but it may be as many as 6.