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[gromarlie]

HI all,
 I have been building and flying model aircraft for more years than I care to remember but all that experience is with glow powered engines but with no experience of electrical propulsion.

The last couple of years have been lousy for flying sessions and as I live on Billing aquadrome I decided to try out boats.

I recently got one of the ThunderTiger Majestic model boats but although I am reasonably pleased with it I have anurge to modify her.
The first idea is to fit water cannons to make her into a fireboat using a cars windscreen washer pump powered of a seperate 7.2 Nimh running through a 5amp controller fitted with a BEC - The main motor is controlled by a BEC equiped controller rinning off the main 6 volt battery.  I am assuming it would not be a good idea to have both BECs plugged into the radio at the same time so the question is :

Would I be correct in thinking that if I disconnct the red wire of the second BECs radio plug will the controller still work but prevent the power from the 2nd battery feeding to the 1st?

[andyn]

I'm 99.99% sure the answer is yes, as the white wire is the digital signal lead, carrying pulses between ESC and Rx. Taking a section out of the red and black leads should do it. Having said that I've not tryed it.

[Faraday's Cage]

To disable the 2nd BEC just disconnect the red wire from the receiver plug of that controller. Its possible with care to prise out the connector from the plug and tape it back - in case you need the facility in the future.

FC

[stallspeed]

You have a 6 volt main battery.What does the controller manufacturer say about bec off 6 volt and how to disable it? Some controllers don't work well off 6 volts at all.

My own preference would be to disable both becsand use a 4.8 NIMH receiver pack or use the 7.2 pack to supply bec.
 

[portside II]

You could disconnect both red lines to the reciever and fit a seperate battery , but my thoughts are that the boat allready has a esc with bec that works fine from the 6v battery , so just disconnect the bec (red wire) from the second esc .
One thing i wonder about is why use a esc to controll the water pump , there is a dual switcher that fits onto a standard servo that would opperate the pump without the need for an esc at all , and the 6v battery would supply power to both the drive motor and the pumpwhich would eliminate the need for a second battery.
daz

[gromarlie]

To disable the 2nd BEC just disconnect the red wire from the receiver plug of that controller. Its possible with care to prise out the connector from the plug and tape it back - in case you need the facility in the future.

FC

Cheers that agrees with my theories

[gromarlie]

You have a 6 volt main battery.What does the controller manufacturer say about bec off 6 volt and how to disable it? Some controllers don't work well off 6 volts at all.

My own preference would be to disable both becsand use a 4.8 NIMH receiver pack or use the 7.2 pack to supply bec.
 

The 6volt system is as supplied by manufacturer and works fine -other parts are from aircraft spares box so already paid for

[gromarlie]

You could disconnect both red lines to the reciever and fit a seperate battery , but my thoughts are that the boat allready has a esc with bec that works fine from the 6v battery , so just disconnect the bec (red wire) from the second esc .
One thing i wonder about is why use a esc to controll the water pump , there is a dual switcher that fits onto a standard servo that would opperate the pump without the need for an esc at all , and the 6v battery would supply power to both the drive motor and the pumpwhich would eliminate the need for a second battery.
daz

The system works fine on a plain switch operated by a micro servo but with my warped mind I fancy being able to control the power from the jets

[malcolmfrary]

You have a 6 volt main battery.What does the controller manufacturer say about bec off 6 volt and how to disable it? Some controllers don't work well off 6 volts at all.

My own preference would be to disable both becsand use a 4.8 NIMH receiver pack or use the 7.2 pack to supply bec.
 

The internal electronics of the ESCs are still going to be worked off the main battery.  If they are happy with 6 volts, no problem.  The boats original electronics might not be happy with an increase in supply voltage, a point to bear in mind when modding an ATRS model.  Having said that, most RC equipment is designed around an assumed standard of a 6 volt supply, with modern semiconductors, there is a steadily increasing tolerance, but its best not to rely on that too much.

[gromarlie]

Thanks for your ideas - I took the chance and took the red wire out of the plug (so I can put it back again if needed) and bingo - it all works as expected  :afro:
On low power just a dribble out the four jets but wind it up to full and 10ft jets - pumping at 1litre in 15seconds