Ok I need some help. car suddenly isnt charging, drove last night 200 miles no problem, today went 20 and it drained the battery dead

Used an inductive ammeter its not charging and the brand new battery volts steady drop as it uses the battery up

No alternators are in stock anywhere for pickup how do I test this one to ensure I need an alt and its not something else.

When I turn the key the battery light comes on as well as other lights car starts all lights go out

1982 volvo 244 dl 4 cyl man trans

Car has run fine for years this just seemed to happen sitting oivernight

 

READ

OK just retested

The battery light is now NOT coming on in key 2

I took the tiny red wire off the back of the alt and grounded it, when i do that the battery light DOES come on in key 2

I grounded the case of the alt with a jumper cable to frame and tested, still no battery light in key 2

 

sounds like a dead diode board on the alternator, or maybe a dead regulator. or just plain dead alternator. dunno what other tests you could do.

 

ok here some insanity

the idiot lights are on, no they arent, yes they are

as i tap the start without starting they are on and off

like a crank position sensor

i drop the alternator leaving the wiring on

spin it

the idiot lights ALL go on and off when in key pos 2 as i spin it around

seems like that alts bad

 

might be the brushes and/or commutators are worn out. sadly, the parts to rebuild these are harder and harder to find, other than the easy regulator+brush assembly on the later style alternators. I'm not sure if an 82 is old school or new style.

some of those old school alternators were fully rebuildable. newer style ones, the regulator is like a power transistor thing on the back that comes off and includes the brushes.

here's the rebuild process for an older style one,
Bosch_repair

 

thanks i just ordered one and with my discount it was only 45 dollars delivered, should be here this week

 

+1.

Had exactly that problem happen with mine... oh, a year or two ago. Things are not grounding properly in your alternator, so, it is backfeeding into your idiot lights. Strange, but true.

I ended up replacing the brushes and regulator assembly all at once, as I couldn't find the brushes alone. And I also payed about $45. That is a bit, but it is a lot cheaper than a new alternator, so I considered it well worth it.

 

note if the commutator is trashed, your new brushes won't last long, they will get ground up.

 

always check the ground wire from end to end, connections can be deceiving.
And then there's that small red wire, the exciter wire as it were) the connector can go away , like that.
then with the car turned off do a battery ground terminal to frame check and see if you get any voltage leaks.
Check the battery ground wire, while you are at it