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]

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.

I went out meaning to do this test yesterday evening - immediately noticed the battery needed charging, so I slapped the charger on and just went ahead and repaired the broken wire (it had to be fixed regardless). Then it started raining, so I called it a day on the car.

-An interesting observation when charging the battery though .. with the car's battery cables still attached to the battery, I hooked up the positive side of the charger as usual, then I added the charger's neg lead to the top of the brass negative cable fitting which gave the tiniest of sparks as normal, but when I readjusted the allegator clip it would aggressively spark when touching the steel bolt of the clamp. I'd never noticed that before was kind of surprised by it. Probably normal (IMG:style_emoticons/default/confused24.gif) but would that be an indication of anything in particular? (like a parasitic draw?, bad battery ground?)

[Superhawk996]

Probably normal (IMG:style_emoticons/default/confused24.gif) but would that be an indication of anything in particular? (like a parasitic draw?, bad battery ground?)

Yeah pretty normal. When you first connect the charger it takes a little time for the current, and the electrolyte ions to get moving toward the plates. Once that is in motion, the current gets flowing more than it was at the initial connection and messing with clamps will generate more sparks than the initial connection.

Please be careful with the sparkage. Battery explosions are a real thing with lead acid flooded cell batteries if the hydrogen gets built up. Not sure if you are AGM or flooded cell but be careful out there.

If there is any doubt in your mind about parasitic draw measure it.