anyone correct me if you see fit
Q: what causes light dimmage?
A: voltage drops
Q: what causes voltage drops
A: when the (electrical) current demand is
a) more than what can be supplied by the alternator
OR
b) more than what can be handled by the wire
OR
c) some other reason that needs to be looked into more in-depthly
Q: what does that mean
A:
a) it means that the alternator can not supply the amount of current needed at a specified operating voltage (usually 14.4 or 13.8) just because the demand is more than what it is capable of. most alts don't put out their max (or close to it) at low engine rpmage. so take that into consideration too.
b) in the case that the alternator is able to supply the amount of current demanded, the size of the wire may be too small to handle all that current. therefore there's more resistance in the wire leading to a voltage drop. sometimes the use of a smaller wire than necessary is done on purpose. for example, the battery+ wire to the starter motor is pretty small, but a voltage drop is expected in order to supply the amount of current.
c) some other reason....one example of this is before, I would have very bad voltage drops even with the big 3....when the coolant level was low. I noticed that the more coolant I had, the less significant a voltage drop I got. Until it came up that the reason why my coolant level was consistently low was due to an intake manifold gasket leak. after that had been fixed, and the coolant level is sufficient, voltage drops are way much less (not to mention I've went from 600watts rms to 1000watts rms [components & subs]). pretty odd and would have to be looked into more in-depthly to figure out the link. but this was just my case....so there may or may not be other "other" reasons.