Originally Posted by Zil
The negative return and positive feed cables do not have to be the same length for any given device. They do have to be the same gauge. Interconnecting positive battery cables must be the same length and gauge. The same for interconnecting negative battery cables. Negatives do not have to be the same length as positives.
When faced with a choice, it is always better to go with the higher ampere rated connections, fuse, bus, or cable, to reduce voltage drop in dc circuits. Especially critical devices.
In practice, if the gauge of any cable is directly related to the length of the cable for any given amp current
. So you might get in to a situation where a higher gauge is necessary for a given run, negative or positive.
And I think best practice is to have a high current
terminal block for most negatives with a connection to the engine
in any case. And it is best to have a separate negative to the alternator
so the alternator
current is not driven through the engine
, especially for high output alternators. And I prefer the engine negative at the starter rather than on a distant place so that starter load is not going through the engine as a whole either.