I just replaced my optima abut 2 weeks ago and it is doing the exact same thing as the old one. When the key is on the volts are in the read. When im idleing in traffic the guage goes down near the read. The alternator is new along with the battery. Could the alternator be causing this problem? When im driving my volts are at 13 which is normal ever since i bought the car. And at times the volts will drop a little past 13 at idle in traffic..

Any one have any ideas why this is happening? I have checked all my connections and they are in perfect condition.

 

you have checked the connection that goes from your block back to your battery then I'm guessing? A new alternator, and new battery and your battery goes dead now. I can only assume that something is not connected correctly, or there is too much grease or grime or whatever at a connection causing it not to get electricity back into the battery.

 

When the car is running, the voltage across the
batt should be 13.8 to 14 or so.
13.0, too low.

 

If i put my stock crank pully back in it will run at 14 but since i have a smaller crank pully it has less rotating mass. How ever i didnt have to replace battarys all the time when i first put it on a few years back it just seems lately that it has been doing this.