Bad battery

The subject: my step-son’s 2010 Hyundai Accent he bought used(but I picked out for him) 2.5 years ago. The battery is a Hyundai branded one, but the date tag doesn’t have any tabs removed, so I’m thinking it’s probably not the original one?

He called me from work last night & said his car wouldn’t start. I could hear over the phone that it was struggling to turn over a couple times, then would stop. It did that a couple times while we were on the phone(and presumably he’d tried at least a couple times prior to that).

He works on base, as does swmbo, but neither have authority to get me into base. However SWMBO’s coworker was in the office & met her there, where the car exhibited the same symptoms a couple more times. Fortunately, being active-duty he does have authority to get me onto base, and once back at the car it started fine...

I put it on my HF charger overnight. Initially it showed about 80% charged. This morning the gauge was at 100%, but the green light showing fully-charged was still red. I disconnected the charger & put a meter on it, which read 12.96v. However as soon as I got in the voltage started dropping a couple tenths at a time until it was just above 12v & I got out. With the doors closed & everything off the battery seems to be holding charge, at least over 10-minutes or so. 

The voltage reads about 14.4v when it’s running.  

So, bad battery, correct? The fact it finally started after cranking & failing a few times is throwing me off. 

I'd say yes.  My battery died suddenly, about 2mi from my house.  Started fine until it didn't.  I called my wife to come get me, but then remembered an old CarTalk episode in which they said that applying a sudden load while simultaneously cranking can actually help.  I tried it again and hit the blower motor switch at the same time and it actually worked!  Drove straight to Autozone and got a battery.  It 'tested bad,' but I'm sure that most do.

If you want to further troubleshoot, check that the cells are full of electrolyte.  If not, add distilled water.  I did this to my Mazda's factory battery after it failed and got another year out of it.

Death throes ...replace it and go on your merry way........ or this if only you have the time, patience , and the proper gear...

https://grassrootsmotorsports.com/forum/grm/learn-me-battery-rehabilitation/142839/page1/

For a DD, especially one that can't always be accessed by the regular mechanic for the vehicle, replace the battery. It is almost certainly original to the car, which means it is probably about 9 years old at this point, and best case scenario is that it failed early in its life and was replaced about 7 years ago. 

You can try the tricks, but you're just kicking the can down the road for a short while. 

Ok, thanks everyone!

For future reference, look at the voltage while cranking. If it drops much below 10.0 the battery is probably bad. Ive seen cars start at much lower voltages but again we're talking about a car owned by someone who's not a mechanic and won't enjoy testing the performance envelope of a failing device (unlike most of us here) so best bet is to slap a new battery in it and leave the finer points of nursing along a POS to the hobbyists. 

In reply to Vigo :

Thanks! It didn’t drop that much, but I’d just pulled it off the charger too. 

Edit: also I noticed when I swapped batteries that the old one was slightly bulged out on the sides. Is that a sign of any problems?

Pete Gossett said:

In reply to Vigo :

Thanks! It didn’t drop that much, but I’d just pulled it off the charger too. 

Edit: also I noticed when I swapped batteries that the old one was slightly bulged out on the sides. Is that a sign of any problems?

Bulging batteries indicate potentially overcharging or internal damage.  Either way, not good and time for a new battery in either event.

In reply to Stefan :

Thanks for confirming that!