Voltage Fluctuating

[kentb]

when my rpm is above 800, my voltage fluctuates from 15 -15.8, and it sucks because my lights go bright then turns darker. everytime the voltage goes down. it doesn't matter if im playing music or not, it still does it.

and i notice that my rpm is also fluctuating. it seems that the whole engine goes slower then goes faster again.

i noticed that this only happens when all my batteries are connected,

it doesn't happen when the alt is only connected to the front battery.

i have upgraded my grounds, all on chassis, then yesterday i connected another ground wire from front battery to back battery 0/1 gauge. but the problem is still there.

do you guys know what's wrong?

i have a kinetik hc1800 in front

3 pcs kinetik hc2400 in the back, 2 runs positive from front to back

all my kinetiks are new except for one in the back, it might be morethan a year old, bought it from someone used.

[E a r t h]

Almost sounds like one of the rear batts is weak, pulling off the other batts and alt to try an maintain charge. That would explain the idle fluctuations when the alt kicks in and pulls the engine down a little to try and compensate for the loss. Try to remove the battery surface charge by turning the lights on and blower motor on high for about 15 seconds with the car off, then check the voltages of each batt seperately ( isolate each batt ). Could also just be a loose connection on one of the batts. Do the simple checks first. Not being able to see this in person makes it that much more difficult to diagnose the problem. Let us know what you find.