Join the Car Talk Community!

Discussion Rules

Welcome to the Car Talk Community!

Want to ask a question or join the discussion? Great! Join now.

Sign In Register

Reading Battery Test Results

Today was the first time I went to Wal-Mart for an oil change. Afterwards they gave me a "Battery Test Results" report saying "Battery fails to meet industry accepted standards and should be replaced" The results are:



Voltage: 12.79V

Measured: 402 CCA

Rated: 550 CCA

Temperature: 92 degrees F



I have no idea what these numbers mean. Do I need to replace it now, can I wait, and if I can wait, about how long?
Tagged:
«1

Comments

  • edited August 2009
    Putting walmart aside for now, tell us how old the battery is.

    Vehicle mileage and year? 3.8L V6 engine?

    IF they measured properly, the battery shows it is/was fully charged. 12.6V is usually the norm. If the charging system is working right, it will likely read around 13-14V when running.

    When cranking the starter it will likely (temporarily) fall to about 8.5V to 9.5V. I know I'll be corrected if wrong.

    The CCA (cold Cranking Amps) is somewhat low and during a cold temp period it may not be strong enough to turn the engine over.

    So, during warm weather you should be ok, but come winter (depending on your location) you might want to replace the battery.

    This is why I asked how old the battery is. Batteries are usually good for 5 years on average. Some less than others.

    Always buy the highest CCA battery and keep BOTH ends of the battery cables/ connectors clean and on wrench tight.

    It doesn't hurt to have an in-vehicle load test done at least once every 2 to 3 years to ensure the charging system works properly. (Sooner if problems arise)

    Keeping battery booster cables handy all the time just makes good sense, but in reality, proper preventive maintenance is what keeps you off the shoulder of the road.
  • edited August 2009
    I know, Wal-Mart. I usually go to the dealer but thought I would try W-M. Won't do that again. Anyway, it has 65xxx miles and is a 3.8L V6 engine. The car's records indicate it was built in July '05.
  • edited August 2009
    Perfectly normal readings for a 4 year old battery. The CCA has dropped a little but that is to be expected. You should be fine for another year unless you park outside in Zero degree weather..
  • edited August 2009
    I conclude since you did not mention it no sign of leaking acid was found at the postive terminal side post. For many years (must have been over 5)Delco batteries leaked at this point. Perhaps they have their act together. Sure made a lot of work for me.
  • edited August 2009
    As far as your CCA goes, I don't trust any of the tester data. The 12.79 is kind of high because most older batteries don't go up that high. Most battery testers probably don't meet any standards. In conclusion: If you aren't having problems you can disregard the test.
  • edited August 2009
    Interesting. About three years ago, my original battery on my 2002 Sienna was 5 years old, so I wanted to replace it. I decided to get what seemed like a really good battery, so I got a Delco Professional, thereby wasting lots of money.

    A few weeks ago, here in Mexico, it failed. Fortunately I found a 24R (The Mexican 24F) locally. But,that Delco seemed like it always had crud on the top, I mean leakage. I put soda on it, to try to keep it down. Not sure if that's a good idea.

    I got an LTH, a Mexican brand, I guess. Next time if I can, I'll just buy a yellow one from Wal-mart. It can't be any worse than the Delco.
  • edited August 2009
    Your battery is fine. Unless you are having any battery related issues, like no-start, etc, I'd just leave it in there until it fails. Unless you're getting ready to take a trip, and have the money laying around, then a little preventative maintenance won't hurt anything, the worse it will cause is for you to be seperated from your money, unnecessarily.
  • edited August 2009
    The problem with letting your battery go 'till it fails is that it could also cost you an alternator. Batteries will fail due to heat and vibration ... if you seldom use your car, a battery will last for 10 years. Under normal usage (15,000 miles/year)a battery should be replaced every 5 years.

    There is no RELIABLE test that will tell you when a battery is about to fail. A load test will only tell you that your battery has already failed and that it's only a matter of time before you experience starting problems.

    If your battery is 5 years old, replace it.
  • edited August 2009
    I really like the conductance test and this is the test that Wally uses. Tells the batterys ability to take a charge.
  • edited August 2009
    There's nothing wrong with the 12.79 volts except for one thing. That does not tell you what the voltage is when a heavy load is applied; such as a starter motor.
    The only way to determine this is by load testing the battery and applying a load equal to 3 X the starter current draw. After 15 seconds it should be a minimum of 10.2 volts.

    This also means the battery should be on a charger for at least .5 an hour before a test and preferably an hour.

    I've seen Wal Mart test batteries with no consideration given as to whether they're testing a battery that has been run down by cranking or one that is weak due to someone leaving the lights on. Bad way of doing it in my opinion.

    A few years ago I went into WM to buy a battery for a project car of mine and took along a 6 month old WM battery that I knew for a fact was good but was simply run down. I did this just for a hoot and sure enough, they tested it and proclaimed it DOA.
    They then offered to exchange it since it was still covered under a non-prorated warranty. I refused the offer and the battery is still chugging along fine at 3 years of age.
This discussion has been closed.