Is my battery dying?

So, I noticed some odd readings on my voltmeter yesterday - or maybe they are normal, and it is the first time I noticed it. It was hot in Chicagoland yesterday, in the 90s if that makes a difference. 1. During start, the voltmeter swang all the way down to 10V 2. Usually voltmeter stays pegged right below 14 - yesterday it was a bit lower, but still above 13 3. Tried to put the convertible top up yesterday, and it stopped right after the clamshell opened - but that may have been headliner binding on the wings. I messed with that, and then it closed. Since I was a bit far from home, and I don't know the history of the battery (bought car last year), I figured I'd just stop in at Advance Auto and get a new battery. I got a Platinum H7AGM, but they wouldn't install it, because it is a Porsche or something... So, now that I'm not making an on the spot battery change, a few questions for the list: 1. Is that a decent battery to use? Right size? 2. I have a battery tender that I use in the cigarette lighter - can I leave that plugged in while changing the battery to avoid resetting everything? I have a CDR-23, so I guess maybe there is nothing to reset. I'll change the battery, but does it sound like something else might be going on? Or maybe this is just normal in hot temperatures? I have some long trips coming up in the next week, so I'd like to be squared away. Thanks pf

When you turn the key on you should see battery voltage. when starter is engaged there will be a volt drop, when engine is running volts go to 13 ish rev the motor and you can get near 14V. It's pretty easy to change batteries in the 996 you should have taken it out and had it load tested at the FLAPS (Friendly Local Auto Parts Store).

Try to find an auto parts store with a modern tester. The old load testing is no longer State of the Art. The new test is Conductance.You get two readings "S.O.H." and "S.O.C." http://www.batteryminders.com/car-ba...motive-charger The main reason for not just load testing is sulphation. An old sulpahted battery can be charged to 13v+ and will hold that charge for a short time. Unfortunately it will be unreliable in terms of how long it will hold a charge and may strand you. The new battery chargers have a cycle that de-sulphates the battery. For these reasons I sold all my old tech testers,trickle chargers, etc. Ideally you need both a new tech tester and a new tech charger and a new tech trickle charger ! More here: http://batteryuniversity.com/learn/a...d_cranking_amp

I just bought one of these at Pep Boys. I killed my battery watching videos in my car (battery was 4 year old anyway).

There should be a date code on the battery ? Usually a sticker with the month and year "A12" would be Jan ,2012.Over 4 years may be suspect? Without test data, how would you know if the battery is good/bad/mediocre ? S.O.H. and SOC ? Alternator performance ? Easy to test when the engine is running. Parasitic loss - more complicated to test correctly .Need a Milli Amp scale meter.

Every time a low voltage condition shows up, you have to consider three things: the battery, the charging system, and the battery drain since these are all interrelated. The easiest is to just replace the battery first if it's 4+ yrs old and if you suspect it to the issue without any tests (note, don't trust the battery test from those auto parts stores too much. If they say the battery is bad, it's likely bad but if they say it's good, it may also be bad). Once you replace the battery, your can keep an eye on the voltmeter. It should be 13.5 to 14.5v whenever the engine is running and even with some accessories on such as a/c, low beam, window defroster, etc. The H7 is a good one but the AGM seems to be an overkill. You can check with Costco and Interstate for a regular battery (cheaper).

BTW, a great affordable battery tester Amazon.com: SOLAR BA5 100-1200 Cold Cranking Amps Electronic Battery Tester: Automotive Amazon.com: SOLAR BA5 100-1200 Cold Cranking Amps Electronic Battery Tester: Automotive The cool thing about this tool is it can tell you the health of your battery, not just a pass/fail. It tells you the CCA measured which you can compare with the CCA of the battery spec. If the measured CCA is much lower, the battery will likely die soon. I also have a 500A load tester and hydrometer in my arsenal but the one above gives accurate diagnosis already. A handy tool to test the charging system Amazon.com: INNOVA 3721 Battery and Charging System Monitor: Automotive Amazon.com: INNOVA 3721 Battery and Charging System Monitor: Automotive

Thanks for all the tips! I'm pretty sure I was just being neurotic - I rarely have the AC on, and I think that kicking in dropped the voltage. I'm so used to the needle being right at 14 it freaked me out a bit

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Lock the car fully when not in use even in the garage. It takes more charge from the battery to keep the car unlocked than it does when it is locked via the computer. If your hear the horn beep once then the car is NOT locked. That sound indicates that something is still unlocked. Ie; door or engine or frunk lid ajar. The car then goes into a sleep mode after 5 days. After 5 days the car has to be unlocked via the key in the door method. A battery is due for a change after 4/5years. Pep Boys will test your battery for free anytime. BTW whenever possible, move the cab top only when the engine is running to save a little on the battery. You do know that you can move the top to open/close via the key in the door don't you??. That's a very handy feature when arriving back to your locked car on a red hot sunny day before you get into the car. That is the only time that I move the top on mine when the engine is not running.