Car won't charge...Battery and Alt both good

[festiva208]

Picked up a festiva a few weeks ago and the owner thought the alternator was bad. I would charge the battery up for a few minutes with jumper cables and it would run for awhile, then when shut off the battery would be dead. I took the alternator out and had it tested, it was good. The battery is almost brand new but had it tested anyway and it was good. I checked the grounds and they are all tight. On the alternator though, there is a little single spade coming out of the back where one single wire would go, but no wire came off of it when I took it out, and there are no loose wires dangling around either. The post for the positive is there of course with the wire hooked up as is the plug in. Don't know if this has something to do with it or not, but any idea's on what it could be?? Thanks in advance!

[Evan93]

my sisters car did something similar, due to a bad diode in the alternator. It causes the alternator to drain the battery when not in use, we would just disconnect the battery when in park until we got a new alternator. The alternator will test good in this case. This may not be the case for you but could be, hopefully someone who knows more will chime in.

[festiva208]

Thanks for the input Evan!

[festiva208]

Tested the alternator while on the car today (first time I tested it off the car on one if those machines as auto zone). With the car running and all accessories turned off, it was charging at 12.8 volts. I know the normal is around 14 so could this be the problem?

[kellen302]

The extra connector is for the electric choke I believe, someone correct me if I'm wrong

[HondaSlayer]

The alt. Should put out 14 volts or more. It is a good chance it is bad if it is only putting out 12.8. My brothers wrangler was putting out about the same amps and it would run for a little then about a week later it would be dead. He changed the alt. And it fixed his problem. Hope this helps and good luck.

[FestYboy]

Tested the alternator while on the car today (first time I tested it off the car on one if those machines as auto zone). With the car running and all accessories turned off, it was charging at 12.8 volts. I know the normal is around 14 so could this be the problem?

12.8 is way too low, MINIMUM is 13.4 with all the accessories on (lights, blower, wipers, radio etc.) that is a bad ALT. i would take it back to the autozone and complain... make sure you have the paperwork to back it up though. and have them retest it in the car and see what their machine says.

[Aspire SVT]

My aspire had a loose 10mm bolt where the alt lead attached to the side of the under hood fuse box. Caused a high resistance and caused the alt output at the battery to read about 13.2 but more like 15 at the b+ terminal at the alt itself because it was trying to compensate for the low voltage it was "seeing".

[M3NTAL]

Mine is only holding 13.00 on idle with no accessories currently.

With radio,lights, sub, amp and blinker on it drops to 11.7

Today I was driving and when I used my blinker it cut my radio off, and threw a e9 code for my wideband which means too low voltage

Picked a reman'd alt off a xr2 today from the yard for $20 bucks so I'll see what it does lol

[PhoenixSHO]

14.4V is the standard charging voltage. Anything lower is a bad alt. 15+V is also a bad alt.

[M3NTAL]

Changed the alt and still same thing, I guess I have to check all my grounds and start from there, then see if anything is drawing power ?

[GenevaDirt]

12.8 is way too low, MINIMUM is 13.4 with all the accessories on (lights, blower, wipers, radio etc.) that is a bad ALT. i would take it back to the autozone and complain... make sure you have the paperwork to back it up though. and have them retest it in the car and see what their machine says.

he never replaced the alt, just had it tested. At least thats the way I read it....

[Movin]

Probably have better luck taking every thing down to
the local DQ and complainen to the girls..

Put a meter on the battery neg post and measure voltage
to the ALT housing, the block, the car body just to see if
you have a good ground system. The car has to be running
with lots of accessories turned on of course.

If that checks out put it on the pos and measure voltage
at the BAT stud on the ALT and at the fusible links, all
6 ends and see what turns up.

[FestYboy]

he never replaced the alt, just had it tested. At least thats the way I read it....

i know he didn't, but i'm saying complain about their faulty machine telling him the alt is good when it obviously isn't. he should have recieved a printout of the results.