Please help! i tested the voltage that reads 12.41v with the car engine shut off and with the car engine running it reads 12.05v and it keeps dropping by 1 every 20 seconds until the car is dead .also the battery charging light comes on .so what might be the problems?

 

yes,still waiting for answer

 

Assuming your battery is good (which is the first thing to check), you have a parasitic drain somewhere.

Close all the doors and take the key out of the ignition,

Best way I have found to find a parasitic drain it to take a multimeter and set it to amps.

Disconnect the neg battery cable. Put one end of the multimeter on the neg battery cable and the other end on the neg battery post.

If you get a reading of more then 50ma then you have a parasitic draw.

Rig the multimeter up so that it stays connected to the battery and you don't have to hold it because you're gonna start pulling fuses.

Start removing fuses one at a time (starting with the underhood fuse box). Take one out, read the multimeter put fuse back in, etc, reading the meter with every fuse until you see the amps drop. A drop will indicate that the draw is coming from that circuit.

Important step:

Disconnect the multimeter before opening the door to check the dash fuse box. You don't want to fry the meter when the dome light comes on. Once the door is open, rig up something to hold the door switch in so the dome light doesn't come on. Hook the multimeter back up and continue the fuse pulling process with the under dash fuses.

Once you find the amp drop, you've narrowed down the circuit that is drawing the power. A wiring diagram at this point will be very helpful so you can determine which components are on that circuit and can then narrow down your problem.

 

Alternator, take it off and to a parts store and have it tested

 

the battery is new from autozone

 

the car is draining battery while running

 

its draining while car is running, not sitting there overnight

 

Your wording wasn't quite specific enough........ And I can't read apparently.

You're alternator isn't charging properly. If you're losing a full volt every 20 minutes its probably time to replace it.

 

do that theirs a very high chance its the alternator I did a parasitic draw on my car that did exactly that except I disconnected the alternator last and could have saved my self the trouble by disconnecting it first

 

Most likely your alternator it's gone (12.05v engine running).

Take it to test.

 

Check for the connection with Alternator and Positive Terminal. Check continuity and voltage drop test on Alternator Ground with Body Ground.

There should not be drop more than 0.5V

 

also the battery light come on

 

where can i find a diagram for wiring for honda civic?

 

does the battery die when the car is off? or hold voltage?

 

it holds charge 12.41v. than when start the engine,it reads 12.01 than drop by 1 every few seconds until dead

 

i mean if you leave it sit for a day what does it do? if the battery holds when the car is off my opinion you have a bad alternator or a bad alternator ground somewhere, which sucks because they are expensive.

 

if it sit there whole day,it would hold the charge.it losses charge when starting it

 

have the alt load tested if you can make it to autozone, Check the alt ground. check the alt power wire make sure it's not loose.