Battery/Starter cable - 25mm instead of 20mm cross section

[CheshireCat]

I am in the process of fitting a new starter motor and at the same time have decided to renew the two cables between the starter motor / battery / cut off switch as well as the earth cable to the starter motor. I also need a slightly longer starter motor cable (15cm longer than existing).

The cables are 20mm cross section at the moment and wonder if there is benefit in using 25mm cable.

Are there advantages and disadvantages of using 25mm rather than 20mm cable ?

[Jonathan Kay]

What's the nominal current of the starter motor?

Are your cables particularly long?

Jonathan

PS: Are those cable sizes 20 and 25 sq mm area? They are sometimes sized by diameter which might cause confusion.

[DJ.]

Thicker cable is heavier, so I would go with similar to what worked OK previously.

[SM25T]

Larger CSA gives lower resistance which is better.

[SLR No.77]

If the cable isn't getting hot during use (from the current) it's thickness is fine.

[SLR No.77]

Clive, out of interest, why is the original cable too short? Have you fitted the starter with the solenoid underneath?

Stu.

[CheshireCat]

Hi Stu

Yes solenoid underneath is that correct ? The terminal is a bit too much of a stretch for the existing cable, 

As my car has a cut off switch which I understand extends cable length i was thinking using slightly bigger cable might be a good thing and offset length.

[SLR No.77]

Yes I've just checked a photo of mine and it's underneath also. I didn't need to alter any cable lengths so if you're 150mm short you must have routed it differently?

[CheshireCat]

The terminals on the Wosp are further away than my Magnetron was. The original cables may have been made to exactly the correct length for the Magnetron.

I think the cable needs to go over the top of the starter motor as the terminal is at the back on the engine side.