jwzimm

Hey all,

I recently bought a battery tender for my 2008 to keep the car charged up while it sits in the garage during the "off" months. Now that my battery is nice and topped off when I go to drive it I have noticed something that the car has always done that has changed. From the time I bought the car (March of this year) I had noted that when you start it the starter would really have to work to turn the engine over. It always started up okay though so I assumed it was just the way these performance motors worked.

Now that I have the tender on the battery though, I have noticed that the car cranks much more easily in the morning. I am starting to wonder if perhaps my alternator is not fully recharging the battery while I am driving. The battery was replaced shortly after I bought the car as the old one tested bad. The new battery is a NAPA unit with the proper CCA and capacity for the car.

My question is, does this sound like an alternator on the way out? If so, would it be a good idea to replace it before it further deteriorates? I assume I would want to try and find an OEM unit if they are still available.

Thanks!

windhund116

You do enough driving to fully charge the battery? Check the battery terminal for good, tight contact. The grounding points of the alternator and battery. And the high tension lines (+) lines from the alternator.

jwzimm

I should have enough driving to fully charge it. My commute is around 20 miles per day.

I know the battery terminals are tight as I did the original battery change and also just checked them again when I wired in the battery tender leads.

I will check the grounds and the leads to the battery and alternator.

flanders

How long did the car usually sit before you started it and noticed it was sluggish?
Might be unusual high parasitic drain, it's pretty easy to check if you got a multimeter.
If you are unsure about the current measurement you could just check the voltage right before you try to start it, this gives a pretty good idea on the battery state of charge.

jwzimm

Anywhere from overnight to 8 hours while at work. I doubt I have any parasitic drain as the car is totally stock. Also, I thought voltage would not tell you much as a battery can have a good 12V reading but that is only surface charge which would not represent actual charge state.

jwzimm

Just checked things. Here is what I found:

Alternator positive lead: Tight and striped red from factory
Battery Negative: Connection at battery and chassis are tight
Battery Positive: Connection at battery is tight

Battery voltage with car off (just disconnected from battery tender): 13.6 VDC
Voltage at battery terminals with engine idling: 14.00 VDC

Thoughts?

windhund116

What weight engine oil are you using?

Chuck S

Get the battery load tested (or buy a $20 load tester). Bad battery can show full charge (12.7v) after 24 hours just sitting there and still be bad as all a voltage check does is measure surface charge, the reason you see a fictitious 13.6v just off the charger.

My seemingly good battery died a year ago even showing 12.6v in the morning.

-- Chuck

jwzimm

Mobil 1 10w-30

The battery is less than 6 months old. I replaced it shortly after I bought the car after the stock one tested bad. I doubt the brand new battery has failed; could it?