He he! I was waiting for something like this JB👍
#1 "(especially with brushed motors- 15A seems excessive)"
Let's get this out the way straight away. The question here is 3 Brushless on one channel.
As an aside here; I haven't yet needed more than 8Amps to get a 2kg boat on the plane and zipping around for an hour or so😊
#2 "ESCs can't recognize cell numbers as the balance leads are not connected."
"if you use NiMh the ESC can only read the voltage coming in and it is impossible for it to read cell numbers."
Agreed JB. The ESC can't 'count' cells, it can only estimate them from the voltage applied.
BUT! As I said; it is easy to fool the ESCs. Set the wrong battery type and the ESC will react wrong. That's why I stressed setting each parameter manually: battery type and number of cells or nominal voltage.
Example:
You have previously set the ESC to run with an NiMh battery, with or without specifying the cell number., and connect a fully charged NiMh battery with ~7.6V. The ESC recognises that as a 6 cell NiMh, nominal 7.2V, and sets an appropriate Cut Off of 1.1V. So far so good.
You zip happily round the lake till the performance wanes and come in for a battery change.

You connect a fully charged 2S LiPo with an O/C voltage of ~7.8V. But forget to change the ESC setting to LiPo. The ESC recognises the 2S LiPo as a 6 cell NiMh and sets the Cut Off to 1.1V!!
Result: the ESC will let you thrash round the lake until the LiPo is discharged to destruction; i.e. well below the 3.0V minimum.

The other way around; LiPo before NiMh - the ESC will spoil your fun well before the NiMh is depleted🤔

I agree with you JB that many folks fit overpowered motors and/or props that are much too large diameter (and/or pitch) for the motor.
That only contributes to excessive current drain without any increase in performance.

"My airboat has a 3648 1450kv outrunner on a 3s 4000mAh LiPo but I'm only using a small 9x6 - (around 30A max) prop to stop it getting hot. If I use a 4s I'd have to go down to around an 8x6, ( a 9x6 on 4s draws around 62A -700W and gets hot) This motor is capable of 1600w on a 6s but would only be used in a 90mm ducted fan at that. Its max efficiency is only 45-50A (taken with a grain of salt) Bit of a convoluted way of making a point, but it is 9.24AM and it's time for bed😂"
All very good advice for an Airboat with with corresponding airscrew JB.
But I see your point and it's loosely translatable to boats and water screws.
I.e. Bigger is not always better!
BTW: I have not yet 🤞 managed to overheat a brushless motor😊
Now nearly 02:00 here 'Up Over' sooooo 😴😴😴😴
Cheers, Doug 😎

Hi Doug, ESCs can't recognize cell numbers as the balance leads are not connected. The 'cell' number settings are only a voltage range setting as previously mentioned, eg, if you use Nmh the ESC can only read the voltage coming in and it is impossible for it to read cell numbers. The reason cell number settings are mentioned is to make it easier for people to follow. Good ESCs usually should have a programmable voltage cut-off where you can make a choice of where you want it to either cut or slow down. Some have a safety built in, where once stopped, you can return the stick to off, wait a few secs and throttle on gently again to get you home.

I'l do a few tests with the Cheapo auto set ESCs to see if there is any problem with recognising 2x 2s batts in series

There should not be a problem with current draw on most models (especially with brushed motors- 15A seems excessive) unless you are using the wrong set-up. The only boats which would be drawing big Amps are racing hydros, cats etc. None of my boats draw more than 6A max (between 2 motors- brushed or brushless) and I think that people tend to over motor or over prop high kv motors, causing high Amp draw (quite often I've seen this done in the name of scale,- ie prop size)

Brushless motors are happiest revving with the correct load, ie, no good lugging a 2000kv motor at say 6000rpm on 12v battery for eg, - it needs to be able to rev to 12000 at least to run cool and not be overloaded. My airboat has a 3648 1450kv outrunner on a 3s 4000mAh LiPo but I'm only using a small 9x6 - (around 30A max) prop to stop it getting hot. If I use a 4s I'd have to go down to around an 8x6, ( a 9x6 on 4s draws around 62A -700W and gets hot) This motor is capable of 1600w on a 6s but would only be used in a 90mm ducted fan at that. Its max efficiency is only 45-50A (taken with a grain of salt) Bit of a convoluted way of making a point, but it is 9.24AM and it's time for bed😂 - over
JB

Hi JB,
"probably could use just one battery on a power distribution board, that's all they do with drones which commonly have 3-8 motors/ESC"
Yeees, you probably could, as long as you're not looking for exorbitant current, like some of the 60-80Amp guys! Would guess that drones don't drink anything like that so the unit can be small and light.
Action do some power distribution boards as well; up to 15-16Amps per output.
https://www.componentshop.co.uk/p102-3-motor-power-distribution-board.html

3x15=45Amps, which will drain a 7Ah SLA in about 9 minutes.
One 3S 7Ah LiPo per motor would triple that to ~28 minutes.
One massive Lipo or NiMh is also not cheap.
May well help with ballasting and trimming to have 3 separate 'lumps' you can move around.
The P40 has no problem with that cos the power connections to the ESCs is after the P40.
"The only problem I can see is if you are using individual motor control, you might get a lag or jitter in other motors if they are on very low throttle and one is moved to full."
That's rather the point of using the P40 JB; i.e. avoiding individual control and keeping the motors in synch.
"The ESC doesn't know if you have one battery or 6 smaller batteries as long as the power coming in is within it's specs ..."
Not knowing type/number of cells correctly can be a problem JB if the ESC is thus not sure how to set it's Cut Off voltage!
It may go on strike when there is still power in the battery. Or it may charge on across the lake until the battery is well below it's danger/damage level 😭
Have to be careful how you manually set ESC for battery type and number of cells - if possible. Don't rely on the so called auto-recognition function of the ESC. It is easily fooled.

I think though that the main reason Action recommend separate batteries might be to galvanically separate the motors and reduce the risk of loops in the wiring causing any instability and also potential fire risks.
I would at least use a separate battery for the centre motor as a 'get me home measure rather than having 'all eggs in one Amp-hour basket'.
Each to his own!
Cheers, Doug

Hi Doug, probably could use just one battery on a power distribution board, that's all they do with drones which commonly have 3-8 motors/ESCs. Makes it a lot simpler and cheaper just having one decent battery. Not sure if the P40 board has a problem with this. The only problem I can see is if you are using individual motor control, you might get a lag or jitter in other motors if they are on very low throttle and one is moved to full. The ESC doesn't know if you have one battery or 6 smaller batteries as long as the power coming in is within it's specs, (ie 2x2s - ESC would be set for 4s (series) or 2s (parallel) etc. Thoughts?

JB

Nobody notice the 'deliberate' mistake?😁
" I also recommend the use of an UBEC to supply the ESCs, disconnect ALL red leads from the plug at the RX. You can then wire the UBEC supply to the ESCs through one switch."
That is nonsense of course!
The ESC derives power for it's own circuitry from the drive battery.
The little switches attached simply make an internal connection to switch the ESC ON.

This part IS correct though; "disconnect ALL red leads from the plug at the RX".
ON NO ACCOUNT connect all the red leads in the RX plugs together!
I would recommend using a separate RX battery to eliminate the chance of any current feedback between the ESCs.
I stand by the rest of my post though.
Sorry for the temporary aberration 😔 (More water with it next time Jeeves!)
Cheers All, Doug 😎

Hi CB,
The absolute easiest way to do this, unless you like experimenting with electrics and wiring🤔🔥😭, has to be to use the P40E motor and rudder mixer board for up to 3 motors from Action Electronics.
https://www.componentshop.co.uk/p40e-marine-motor-mixer.html

As JB says, before you start plugging things together you need to make sure all 3 ESCs are set up identically. The easiest way to do this is to use a programming card.
The ESCs all need to be set for identical mode (forward/reverse NO brake for boats) and motor timing.
Second they also need to be set up to recognise Neutral (stick centre), Full forward (stick up) and Full reverse (stick down) commands from the TX, so that they all react the same way to the TX. This should be covered by the ESC instructions.
Then use the P40E instructions to set up the degree of rudder mixing you want😉
Like JB I also recommend the use of an UBEC to supply the ESCs, disconnect ALL red leads from the plug at the RX. You can then wire the UBEC supply to the ESCs through one switch.😊 You will note from the P40E instructions that you will need 3 IDENTICAL batteries to supply motor power to the ESCs.
Bon chance mon ami🤞
BTW: this is how I plan to power the ELCO 80 PTB I am (slowly🙄) restoring.
Hope this helps,
Cheers, Doug 😎

Hi CB90, You might be able to run 3 motors using 3 ESCs by removing the red wire from all 3 ESC to RX leads, making a 3 into one RX plug (must be able to plug/unplug each ESC lead,- will require soldering up leads,) , and using an external UBEC (maybe 5A+) to power your RX. You will have to set each ESC individually (1 at a time,- turn off, unplug,-next one etc) so they are exactly the same stick/trim settings etc before plugging them all into the 3 into 1 RX plug . They should all start simultaneously from 1 switch or as required from 3 (if they have separate on/off switches.) You would of course need a 1 into 3 ESC power lead/board as well (you can buy these for quadcopters/drones, - see drone power distribution board on Ali Express / EBay etc ) You'd need to buy/make a board to match max A plus, for 3 motors

Problem might be that they run at different speeds due to slight differences in motors/ESCs etc. This is just an idea, as you need to do a similar procedure for quadcopters (I have a quad ducted fan model with 4ESCs, 1 RX and a KK control board which requires this to set up but this uses 4chs). Shouldn't damage anything if you are careful, but of course ENTIRELY AT YOUR OWN RISK . Not sure if you have reverseable ESCs or not (ie fwd and rev)

You might be able to program your mixes to run off one stick also, (using 3 chs normally). If you need proper reverse control (ie if you have boat/car ESCs with reverse) you'd be better to use 3ch on your RX/TX (still need only 1 power input to RX no matter how you work it - ie removing the 2 other red wires or removing the 3 and using a separate UBEC for RX power as previously mentioned) simplest way would be to use L stick for 1 motor, R stick for another, and a rotary switch (proportional) or toggle (on/off full,- or % limited by programming) for center motor ? for cruising, or with other 2 for full power etc.

The experimenting is up to you. Let us know what your set-up is to be used in so we can get a better idea. There are lots of triple motor / radio set-ups done on the site to get ideas off as well.
JB