Did I get a dud battery

Hello,
I bought a 27F 710 CCA Interstate battery from Costco last month. I noticed when I started it yesterday the starter sounded slower. I checked the voltage and it was 12.6. I drove it for about 40 minutes.
I checked it today and its 10.5. I checked the amp drain and its 65mA so not too bad.
Voltage at battery while running is 14.0 volts so I believe alternator is OK.
Can this be bad already?

 

Guess it depends on why you needed the new battery to start. May have an underlying issue the battery replacement didn’t solve? You check all of the cables and grounding points?

 

Definitely a drain or maybe a weak alternator/voltage regulator. Probably can get a local autoparts store to check the charging system.

 

Age. All cables seem fine. Trying to be proactive.
Voltage at battery while running is 14.0 volts so I believe alternator is OK.

 

Carry it to any local auto parts store. Have them test it.

It sounds like it may not be getting a charge, personally, based on the voltage drop. Cars won't start without voltage and the amperage to deliver that burst of voltage (CA/CCA). For a dud battery with a good functioning alternator, I'd expect to see regular voltage of 12.5v+, but low CCA.

The fact the battery keeps testing incrementally down in volts makes me think the line from the alternator to battery isn't tightened correctly on the terminal, or the positive or negative terminal are loose enough to wiggle (with or without force).

 

10.5 volts could be indicative of a bad cell in the battery. Have it load tested.

 

Probably bad ground.

 

to that point, 6 cells per battery @ 2.1v per cell. At that math, 5 good cells = 5 x 2.1v = 10.5v if one cell was bad.

 

Nothing loose. Getting a good charge.

 

If you turn off the truck, wait half an hour and test again, and it's under 11v, @KNABORES is probably dead-on.

 

This must be fancy 2006 hardware!

 

Nothing but the best for the Tundra! Viper alarm/remote start.

 

Thought maybe later years had underhood lighting

 

Classic pin switch

 

We have a winner! Confirmed by parts store.
Went to Costco and exchanged it for a new one.
Just hope it lasts longer then 6 weeks!
Thanks for the replies.

 

I didn’t think you could have a bad cell with a new battery. Guess I learned something new.

 

All brands of batteries have duds now and then.

 

Everything non-OEM sucks these days.

 

At $120 its the best deal I can find on a 27F.

 

That’s just poor quality control though. OEM probably tests them to a higher standard since they all pretty much come from one off two suppliers, IIRC.

 

I pretty much pay $90-$120 for OEM since their 84 month warranty gives me anywhere from $30-$50 off.