Does anyone know how to read /determine the age of my Interstate Battery Mega- Tron. It has stamped into the top the following - I6C
The battery was in the car 2 years ago when I bought it..
Have been unable to locate an Interstate Battery dealer to ask them.
My voltage is going from 13.4 at 2000 rpm down to 12 volts at idle with A/C on.
Don't want to replace Alternator if the Battery is out of date and weak and causing the problem.
Thanks for any response
Rick

:confused:

 

Dating is really insignificant. To answer you question you really need to do two things.

1.) Charge battery; disconnected from the car on an auto charger for about two days. Disconnect from charger and let sit overnight or at least 8 hours. Check voltage level with a good DVM , should be about 12.6V. If you can remove the covers and check the electrolite with a specific gravity tester, that will tell you much more, and by cell (tester is less then $20 and has directions, readings depend upon temperature). A load tester is also great, but expensive; many battery stores will load test a battery for you, but this is useless (as is the specific gravity tester and voltage) if the battery is not fully charged.

2.) If battery tests good install in car. If over the next few long drives the voltage still drops to 12.0V at idle I would not panic, but suspect the alternator is about to give up the ghost. Confirm this voltage with a good DVM, but should never drop below 12.6V often or car is actually depleating the battery.

Don't buy a "lifetime" warranty alternator from a chain store unless you like using up your lifetime changing out alternators. Take your alternator to a good MARINE alternator rebuilder near you. Also keeping underhood temps as low a possible will help a little with alternator life, as will keeping the battery terminal connections very (remove bolts and replace) and tightened properly.

Pete

 

Your voltmeter readings are normal and you have no cause for alarm. The alternator cannot put out its rated current at idle speed and the battery supplies current which causes the voltmeter to read lower, near 12 volts. When cold your alternator will put out about 14.3 volts and it drops to 13.3 when it gets to its operating temperature. At stoplights and idle, your voltage will drop with a lot of electrical eqt on, but as soon as you get underway the voltage will rise and the battery will be charged. I don't think there is anything wrong with your alternator.

 

Thanks for the info and feed back..I only drive the Vette one a week and was concerned the 650 cranking amp battery might be getting old, and can't stand to have anything wrong with my car..
I think I will have it checked out to be sure for peace of mind..
Stay safe,Rick