No Alt. light after start up but battery not topping off .. Options

[Literati914]

My battery was bought last month.. Alternator light comes on with the key on, but goes out at start up. Battery keeps running low and eventually won't start the car. Does this point to anything usual - VR maybe?

[Literati914]

Also, I just found the following break in the wire casing of the brown wire at the relay plug! - think that’s enough to cause my charging issues?

[Superhawk996]

Also, I just found the following break in the wire casing of the brown wire at the relay plug! - think that’s enough to cause my charging issues?

Yeah!

The color of the copper underneath doesn’t look healthy. That wire (D-) brings ground up from the alternator to the voltage regulator. Without a good ground reference the voltage regulator cannot operate properly.

There is no guarantee this is your only problem. Per previous posts you also had 0.8v or more drop between D+ and the battery positive post.

Kelty360 has it right - address root cause(s) of voltage drops rather than adding grounds everywhere hoping for a fix.

If you want to measure the voltage drop in that cracked wire:

Use meter (milli-volts scale).

Engine running - voltage regulator plugged in. That alternator connected - plugged into the relay board.

Meter ground lead to alternator case. Where the lead is placed matters. Measuring to the pivot bolt or fan should will not give an accurate measurement.

Meter positive lead to the spade connector on the cracked wire, of that 3 pin alternator connector. You have to back probe that connector while it’s plugged into the relay board.

Reading should be 0.0v

Anything higher than that indicates corrosion in the wiring and a voltage drop across that wire.