Two motors & two ESC's and a WYE connector to receiver -something needs to be cut ??

[MikeP323]

My twin Cheetah is starting to near completion and I understand that one of the red esc wires needs to be cut. I would guess that would be coming from one of the ESC's prior to getting to
the Y - is that correct? And then the esc with three wires must always have power applied first and turned off last?? I remember reading something about this back before I ever thought
about having a twin but the memory is gone and I can not find the item in the forum. Do I have any of this right?

Any help with these steps from an experienced boater would be appreciated. I have a Zelos 36 and that boat does not have this requirement unless it was already done for me! Those
two esc's are energized simultaneously. https://forums.offshoreelectrics.com.../confused1.gif

[Speedfreek]

Sounds good to me if you are using one of the ESC to give power to the RX.
Side note i wouldn't cut the wire just lift the tab up and pull the red wire out and put some heat shrink on the red .

[RaceMechaniX]

Ideally you would remove both red wires and use a spare receiver pack with switch. This reduces the stress on the one ESC with BEC.

[MikeP323]

Tyler I appreciate the reply - what size (mah) would a lipo have to be? I dont like the idea of putting four AAA cells in there for weight consideration.

[madmikepags]

2 cell lipo if your receiver and servos are high voltage, if not get a 2 cell LiFe

[MikeP323]

Receiver is a Spectrum SR 210 which model I now have in 10 plus boats & no problems and the servo is a Hitec HS645MG which I have never used before but it fit
where it was supposed to and another guy in the club has one in his Enzo/Cheetah and has been running that for some months with no problems. I do not believe
either of these are high voltage. So how many mah does the battery need to be?

Thanks for the reply.

[madmikepags]

you can use a 1700mah LiFe but I prefer the bigger 2200 spectrum transmitter packs, they last a whole weekend of racing without recharging and I fornd them on amazon pretty cheap.

[RaceMechaniX]

Use a LiFe pack if in doubt. 1500-2200mAh is plenty for an entire weekend.

[MikeP323]

Thanks to you both for the info - I ran it on the bench today and all seems well so far. Then getting it wet starts the hard part. When I tested it today it was with the right ESC feeding
the receiver. Not sure which way I will go yet but thanks to you guys at least I have the knowledge. MIKE

[Prodrvr]

Ideally you would remove both red wires and use a spare receiver pack with switch. This reduces the stress on the one ESC with BEC.

Best advice right there. I recommend the same exact thing to others...be it boats, trucks, or even more importantly...planes.

[MikeP323]

Prodrvr - or anybody - Just asking as most of my electronics knowledge is ancient - why is it important to power the receiver with a separate pack? It would seem like
the amount of amperage used is almost negligible. Does the uneven drain on the ESC's make for a problem or is it that the two motors (or one) may not be getting
a full or equal amount of current? Thanks for your reply!

I was just looking at a Spectrum 2s 2200 mah 6.6volt LiFe receiver battery on Amazon - is 6.6 volts to much? I would think that would be OK as some of the UBEC's
I have used have a 6 volt output optional.

[RaceMechaniX]

Most ESC's do not have very capable BEC circuits especially the ones for boats. Rudder loads can be very high and if you have a high output servo this can easily draw 10A in some instances.
Batteries are very good at handling high spikes and sustained current draw. It is more difficult for a BEC circuit to do the same. BEC's are also usually not cooled like the power board in most ESC's so they heat up and loose efficiency which makes them more prone to failing.

Heli ESC's tend to be the exception where manufacturers intentionally design for 20A BEC loads.

[Prodrvr]

Prodrvr - or anybody - Just asking as most of my electronics knowledge is ancient - why is it important to power the receiver with a separate pack? It would seem like
the amount of amperage used is almost negligible. Does the uneven drain on the ESC's make for a problem or is it that the two motors (or one) may not be getting
a full or equal amount of current? Thanks for your reply!

Running the steering servo in a boat as RaceMechaniX said, can draw a lot of amps, which adds additional load on the esc. Now in electric planes, and in my case, 4 figure planes, if the esc craps out and you're not running a separate battery to run the Rx and servos, guess what? The plane goes in because now you've just lost all control. I'm certainly not gonna roll the dice in using the bec.

[madmikepags]

As Tyler said most of these controllers don't have a good quality BEC built into them, that board heats up and the controller gets hotter. I don't mind it on most of my single setups but with twins I want everything to be in sync and perfect, a Battery provides that.

[MikeP323]

RaceMechaniX - Prodrvr - madmikepags - Thank you all for your help. I am convinced and will be ordering that Spectrum unit I mentioned.
The boat will be in the water tomorrow for some basic tests and if I get it back home again (without calling the scuba club) I will be happy for a first day -
I really do appreciate the help guys !!!!

[Prodrvr]

[RaisedByWolves]

Dontt any of the boat ESC's have the switching type BEC?

What about a stand alone UBEC run directly from the battery?

IIRC a 10A continuous runs about $20 and weighs next to nothing.

ETA, found this.

https://www.motionrc.com/products/ca...yABEgLnh_D_BwE


Not trying to sway anyone, just curious as this seems like a simpler setup.

[madmikepags]

I used to use these really nice BEC's I think they were Hercules? could handle up to 20 amps. 2 caps and a voltage regulator and you could switch fro 4.8 to 6.6 volts by just changing a small plug. But with the extra wires they got to be a pain in the ass and I actually ended up either losing them or sellng them w boats.

[RaisedByWolves]

I used to use these really nice BEC's I think they were Hercules? could handle up to 20 amps. 2 caps and a voltage regulator and you could switch fro 4.8 to 6.6 volts by just changing a small plug. But with the extra wires they got to be a pain in the ass and I actually ended up either losing them or sellng them w boats.

Yeah, western robotics makes them. The PRO Heli guys all use them and their running 4 servos plus electronics under severe flight conditions so power wouldn't be an issue.

I dont race but I prefer to keep things as simple as possible and for me an added battery is just another thing to maintain and remember to charge.