My 24V 200ah batteries came with what I can measure are 5mm core battery cables, I was not happy so used 8mm core battery cables. My question is why do they supply such thin core battery cables, surely it can be a fire hazard, I have attached a photo for size comparison

1 hour ago, Elro said:

surely it can be a fire hazard

what is the rating of your battery? 1C, 0.5C aka C/2, if it is rated at 100A (C/2), then the cable supplied would probably be ok, I think, also, is the suppled cable insulated with a silicon jacket? again, if so, its current carrying rating would be higher than a PVC jacketed cable.

Thank you for the info.

There are four factors which determine the cross sectional area of a cable

A] Cable Length

B] Cable Resistance

C] Operating Temperature

D] Current

Cable length and the cross sectional area of the cable has an influence on the resistance of the cable. The operating temperature also influences the resistance of the cable and also determines the type of insulation used on the cable. The current that the cable must be able to carry also influences the cable cross sectional area.

Silicone cable has a wider operating temperature so a thinner cable can be used for a short distance because the insulation of the cable would be able to handle the heat where PVC would not be able to handle the higher operating temperature and a thicker cable would be used so that the cable would not heat up and burn the insulation off.

To determine the cross sectional area of the cables in your photo one must either look at the cable insulation and see if it is not indicated on the insulation or measure one of the strands in the cable, calculate the cross sectional area of the strand measured and then count all the strands in the cable and multiply that by the cross sectional area of the one strand and that would be the total cross sectional area of the cable.

1 hour ago, GerhardK83 said:

There are four factors which determine the cross sectional area of a cable

A] Cable Length

B] Cable Resistance

C] Operating Temperature

D] Current

And perhaps an "E" for Acceptable Voltage drop. An acceptable voltage drop of (say) 1% on a 24V system will be much less than a 1% drop on a 48V system, and one might have to use a thicker cable on a lower voltage system with the same current (depending on cable length and resistance).

1 hour ago, GerhardK83 said:

Cable length and the cross sectional area of the cable has an influence on the resistance of the cable. The operating temperature also influences the resistance of the cable and also determines the type of insulation used on the cable. The current that the cable must be able to carry also influences the cable cross sectional area.

Silicone cable has a wider operating temperature so a thinner cable can be used for a short distance because the insulation of the cable would be able to handle the heat where PVC would not be able to handle the higher operating temperature and a thicker cable would be used so that the cable would not heat up and burn the insulation off.

To determine the cross sectional area of the cables in your photo one must either look at the cable insulation and see if it is not indicated on the insulation or measure one of the strands in the cable, calculate the cross sectional area of the strand measured and then count all the strands in the cable and multiply that by the cross sectional area of the one strand and that would be the total cross sectional area of the cable.

Solid advice Gerhard 👍