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Battery not charging

7.1K views 14 replies 9 participants last post by  shizenshrestha  
#1 ·
When I was driving the other day. .. the car just died.
I tried to restart it the battery was completely dead.

So I had the battery re-charged with the battery charger the car started and it ran.
I thought the alternator went bad but I replaced it about 6 months ago.
I checked the voltage at the battery terminal with engine ON I see 12.3Volts.
When I checked the voltage at output of alternator, I see voltage close to 15volts. If the engine is ON it should be someting like 14.5V right ?
I checked the fuse too .. it was ok. not blown.
Theres a replay too which I dont know how to check.
I need help what else could be wrong .. where to start off with.

Appreciate any ideas and help;

Thanks.
 
#8 ·
When engine on the check the battery terminals, they must have 13.0 or more. Not Too Much!!! Then Turn on ligths and Air Conditioner check again , it must 12.3 or more it depends, If gets to 11v or less then its not charging, Also check if the Positive Terminal its getting Very hot. Check Fuse box if they have the corresponding fuses. Also disconnect the battery and check the Voltage if its getting low.
 
#9 ·
12.3v sounds a little low even for a battery that's not being charged (engine off) and with engine running it should be more like 13.5(ish)-14.xx (see chilton)

Could be a bad connection to the battery.

Not saying your alt is bad but AM alts have been known to cause a lot of problems. I replaced 3 p-boys in less than 4 weeks one time and have heard similar stories by other members here.
 
#11 ·
I was checking the continuity between the wires .. n then came out with some questions.

What are those two terminals in the harness on alternator ?
one of them had continuity between both positive and negative socket of battery which I was thinking it should be continue with positive only.
if it is so .. I am guessing some short in alternator .. does that sound right ?

any idea ?

also I didn't have continuity between B terminal (on alternator) and positive socket of battery but there was between negative socket.


Thanks.
 
#12 ·
SuperDave said:
While the car is running take off the Neg(-) battery terminal. If the cars dies, then you have a bad Alternator or wires leading to the battery from the alt.
Bingo, unfortunately im assuming it is the alternator aswell. It will run with a battery pack on it if you have a bad alternator and when you take it off it will die pretty quick if not right away.
 
#15 ·
ya finally it looks like my alternator is bad.

I took it to NAPA and had the battery charged .. it was good.
had the alternator checked too .. they said there's no output.

IS there anything else I can check on alternator guys ?

Im trying to save some money for other parts so I would be nice
if anyone of you have idea to test and repair the alternator.

Thanks.