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electrical charging

 
trae44
I love my Chevy Chevette!
Posts: 1
Joined: 12/10
Posted: 12/27/10 09:01 PM

i have 97 corvette and  just wanted to know what is normal generator charging range for this car. I just replaced ti battery and at idle its about 13.9 but if i turn on the head lights and the ac or heat it drops down to about 12.9 to 13.1. Im learning more about the car now as it was my fathers but he passed away so if someone could please answer my question it would be a great help  

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waynep7122
I mow my lawn and find Chevys
Posts: 1114
Joined: 08/09
Posted: 12/27/10 09:18 PM

in order to properly test the charging system...

the battery needs to be tested to see how much percentage of charge it has...

or you will find an lower voltage than expected as the battery is pulling the voltage down as its accepting a charge...

engine OFF... turn on headlights for one minute...  turn off headlights...

measure battery voltage..

12.65 is a fully charged battery.

12.45 is a half charged battery

12.25 is a quarter charged battery...

batteries that are below full charge really need to be brought up to a full charge on a battery charger... 10 amps for 30 minutes or until the amp meter on the battery charger drops...

i would also like to know if you have cleaned and verified the battery cable terminals are clean and bright inside behind the bolt...

i seem to recall that there was a TSB.. technical service bulletin.. about a positive battery  terminal stud where the positive battery cable goes to and splits off to many smaller wires...

these studs have come loose and burned the ring terminals causing resistance in the system... and charging problems like you describe...

with the engine running.. you can do a voltage drop test in under 5 minutes...

set your digital volt meter to 20 volts DC scale...

start the engine... turn on the headlights...

measure the charging voltage at the battery..

14.1 to 15.3 on a gm...  probably 14.6 to 15.3...

then..  measure the negative battery post to the engine block... 0.04 volts..

measure the negative battery post to the chassis ground..  0.02 volts..

measure the engine block to the chassis ground...  0.02 volts ..



a few more..   if you can get to the output terminal on the alternator...    measure that to ground..   should be the same as the charging system voltage...  but you should also measure the alternator output terminal to the positive battery post...   this may be more than 0.04.. but not much more...    these tests can only be done with the engine running.. and the headlights on..

since electrons flow from negative to positive..

if you have a bad ground.. you will see a difference in voltage between 2 parts..

if you have resistance at the positive terminal under the hood.  you will have more voltage than i posted...

hope this helps...

you probably want to print this...

you can also check the TSB titles over at  alldatadiy.com  

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