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>> Home > Forum > Electrical Related > correct size of wiring
correct size of wiring
(49 views)
Author Message
octman
(Commander)





Forum Posts: 84
8th Aug 2017 14:30  
>> Permalink
mdlbt.com/31821

I apologise if this has already been covered here but I am now at the point of installing the motor in my new model. The motor is a Graupner speed 600, and the specs are :
Nominal voltage 8.4 V
Operating voltage range 4.8-9,6 V
No-load rpm 15500
No-load current drain 1.8 A
Current drain at max. efficiency 11 A
Current drain when stalled 70 A
Max. efficiency without gearbox 75 %

If I use 8.4 volts what size wiring do I need? Do I need to cater for the 70A current or the 11A current, or somewhere in between, with a fuse?
Sorry to be a bit dim on this but I am confused (with most things these days!)

Chris

RNinMunich
(Fleet Admiral!)





Forum Posts: 597
8th Aug 2017 14:45  
>> Permalink
mdlbt.com/31825

Hi Chris, no you don't need 70A wire! 😊 That might be horribly thick and stiff for a scale boat.
You need wire the same size as probably on both your motor and battery. Same the 'standard' wiring in cars. Available I suppose at Halfords and any car diy shop.
WHAT YOU DO NEED IS A 15 OR 20 Amp FUSE TO PROTECT THE WIRING IF THE MOTOR STALLS (PROP GETS BLOCKED) 😡
If your ESC has a BEC supply for the RX put the fuse in the positive motor lead, probably red or yellow. If not, i.e. you have a separate battery supply, put the fuse in the positive lead from drive battery to ESC.
Then at least the RX will still work and maybe you can see from shore if it still responds; e.g. by switching on lights or some other visible function.
With twin or more props fusing the motor wire itself can sometimes help get the boat home on a remaining engine.
Somewhere in the Electrical stuff blog is a long discussion on the subject!
Have a look here
https://model-boats.com/forum/electrical-related/28332
"What type of wire?"
Happy sailing 👍 Cheers Doug 😎
PS: Almost forgot, if you have a brushless motor you have no choice but to put the fuse in the positive wire from battery to ESC! Brushless ain't got no positive!


"Retirement is when you stop living at work -
and start working at living/boat modeling!" 舰队的海军上将 😉 Doug