Need to extend a solar panel cable,it’s a 10w,0.64a capacity,I only have spare cable of 1mm od,including insulation,is this suitable for joining to cable 3x that diameter or can it cause resistance problems? TIA.
The thicker the cable you have the better, lower resistance per metre…minimise your losses, what distance are you going?
I assume you’re using copper cable?
I'll guess the conductor is about 0.6 mm diameter....
Resistance of about 8 feet is 147 mOhm (0.147 Ohm)
Power = I^2 R = 0.64 ^2 * 0.147 = 60 mW of power lost to heating in the cable
Voltage drop over the additional wire = I * R = 0.64 x 0.147 = 94 mV
Power loss and voltage drop are therefore minimal.
The above calculations are a simplification of the actual circuit. They assume the current remains at the theoretical 0.64 A, which it won't. However, they are okay for indicating the maximum power loss and voltage drop.
@nickk personally I would advise thicker cable if only on the basis that it is easier to work with, more durable, etc. Tri-rated cable is useful for many projects.