Alternator/ Electrical¿?

[loominaz34]

So my car is putting out 14 volts when running (jumpstart) , but the second I turn the car off, the battery falls back down to about 10.6 volts. no matter how long the car runs for. I put jumper cables from my dad's car to mine and the battery charged some so I know the battery is good and the wires are giving like 0-5 ohms resistance so they're good.

O yeah its a '92 Z34

Does this mean that I need a new alternator or am I missing something?

[paulo57509]

So my car is putting out 14 volts when running (jumpstart) , but the second I turn the car off, the battery falls back down to about 10.6 volts. no matter how long the car runs for. I put jumper cables from my dad's car to mine and the battery charged some so I know the battery is good and the wires are giving like 0-5 ohms resistance so they're good.

O yeah its a '92 Z34

Does this mean that I need a new alternator or am I missing something?

 

What are you using to measure voltage? Not the dash gauge, I hope.

 

I take it that the engine doesn't crank over?

 

The alternator is putting out 14 volts so I'd say that the charging system is working.

 

Regardless of charging via jumper cables; beacuse that battery doesn't hold a charge, I would suspect a bad battery or connections.

 

Can you try taking a known good battery and installing it into your car and take the same measurements?

[Smoke1991]

so wait, after you get your started, and then pull off the cables, the voltage drops to 10? and thats your car being powered by its own altinator.

 

then yes, new altinator for that situation. ( maybe a short but doubt it)

 

to test the batt i usually stress it then read with a volt meter, if the batter is left on a charger overnight, put it in next morning, start the car, let it run for 5 min, turn off, then take a volt meter to the terminals, while someone is cranking the car over to see if it starts, read the voltage, if that drops below around 9 volts, its on its way out. But then again, you gota make shure your altinator is good.

 

if you have a pepboys or a car place that has a battery testing machine, it puts the battery under loads n stuff, and tells if its any good. and its a free test.

 

one quick Q, has it recently been doing this, was your car working good b4?

[loominaz34]

The battery's brand new so I doubt that it's bad. And the voltage drops to 10 after I shut the car off. The connections aren't bad, reading 1 and 5 ohms for positive and negative from alternator to battery and block to battery. Any other suggestions?