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battery postion ?

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Pete Crosby25/04/2020 07:56:39
107 forum posts
44 photos

I'm building a Parasol wing model which has the pusher motor mounted on it,

I was wondering what the max length of battery cable is ok to use.

The model is a Curtiss wright CW1 junior, and would like to maybe install the power wires hidden inside the wing supports (tubes) Slightly oversize rather than have the power leads exposed. so I can mount the battery inside the fuselage

I can mount the esc right next to the motor (thumper V3 3548. 900kv)

Tom Gaskin 125/04/2020 08:20:09
50 forum posts
5 photos

It is generally accepted that battery to ESC should not exceed 20cms - the ESC to motor can be almost as long as you like!

You can extend the ESC to battery leads but you then get into fitting extra spike suppression capacitors to protect the ESC.


Simon Chaddock25/04/2020 09:14:20
5844 forum posts
3100 photos


The problem is the existing ESC has capacitors on the battery side to give the spike protection so it will work with longer than recommended battery to ESC wires BUT the longer they are the more it overloads the capacitors so they will start to deteriorate and eventually fail, usually at an inconvenient moment. wink 2

If it looks like they would be unduly long is there a possibility of running the motor wires through the struts and placing the ESC in the fuselage closer to the battery.

I have an EDF where the motor wires are no less than 900 mm long to get the ESC close to the battery positioned in the nose. smile o

Pete Crosby25/04/2020 09:24:45
107 forum posts
44 photos

Ah right so I should keep the battery leads short and can extend the esc wires to the motor ?

So now I would need a method of getting all three wires down to the fuselage, lots of thinking going on this morning... up way to early for the brain I think.

G-JIMG25/04/2020 15:49:38
158 forum posts
120 photos


Ancient tribal knowledge dictates the Battery to ESC wire should be as short as possible. However, like most tribal knowledge it eventually gets overtaken by advances in technology. Although it is perfectly true this used to be the case, the latest ESCs make it much less of an issue. Quality ESCs (not necessarily cheap Chinese knock-offs) have improved circuitry and the Triacs they now use are far less susceptible to spikes.

If you haven't already purchased your Motor/ESC I suggest you email George at 4-Max. He will be able to advise you on max wire lengths, etc.


Keith Berriman25/04/2020 16:11:28
846 forum posts
7 photos

I built the depron Euro Fighter as seen on BMFA pages and took the option to extend the battery wires by 9" or so and had no problems. I assume on a 250 watt motor this was okay. Maybe on larger watts motors it could cause problems. I was using the ZTW Beatles ESC.

Pete Crosby25/04/2020 18:25:24
107 forum posts
44 photos

using a Turnigy Plush 60A with a overlander thumper v3 3548/05 900kv 710watt

maybe a 4s 5000 battery for a bit of playtime

Edited By Pete Crosby on 25/04/2020 18:26:15

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