Electrical Gremlin
 

1989 Civic DX Hatch 5spd D15B2 motor
170 amp Alterstart alternator
0 gauge wire from battery to starter
0 gauge wire from battery to under hood fuse box
0 gauge ground wire
First symptom:
My battery light in my cluster is flickering. Not flashing, flickering. At idle it stays off. When I rev the engine it flickers lightly. When I'm in gear and giving it throttle it flickers almost to the point of strobing.
Second symptom:
The other lights in the cluster all glow slightly at high RPM's.
Third symptom:
Battery seemingly dying. Ill turn the key to start and it will half crank then stop and my Voltage meter will say LO. I wait a few minutes and the car stutters to a start.
Fourth Symptom:
I have a Stinger digital voltage meter. It jumps from 12v to 13.8v while I'm driving. The alternator tops out at 14.1v under full throttle. That's normal. But sometimes ill be driving and it will stay at 12v then jump to 13.2 like its supposed to then drop back down. The fluctuations are completely random.
Any ideas?
Troubleshooting suggestions?
Thanks in advance.

This sounds like a bad alternator. Try putting your stock one back on if you still have it. You should also check that the alternator gets power on the small black and yellow wire with the key on.

Not the alternator. There are issues even when the car is off.
Update:
When I turn the key to the on position the lights in the cluster that stay on are the signal light indicators and the high beam light indicator. When I turn the key to start nothing happens. Then I pump the clutch a few times, the indicator lights shut off, and I turn the key and the car starts like normal. Then again when I'm driving the battery light flickers, the voltage jumps around, and the indicator lights flicker.

Seemingly unrelated electrical systems interacting in strange ways is usually a bad ground. Check the cluster ground, which I think is behind the cluster (or somewhere in the dash area). How much other wiring has been modified?