Hey Gang-

So, I have a 2012 XC70 T6 that I just picked up about a week ago. Everything was great for the first week, no issues. About two days ago, I went out to start the car and it barely cranked. I got a "Low Battery" message on the dashboard. I made a few additional attempts, and it started, (Barely).

I placed a battery-tender charger on it for about two hours, and then my wife drove it on two short trips. It made it out and back home again, but barely started both times.

I placed the charger on it overnight, intending to give it a good thorough trickle-charge. I checked it in the morning, and the yellow light on the charger was illuminated, indicating that the battery still wasn't charged. (Not sure if it was a poor connection on the terminals; it seemed fine).

So, we took another longer trip (about one hour), and I figured that would be enough to recharge the battery. (Any of my previous cars, an hour was always enough time for the alternator to bring a low battery back to life).

When we left to drive home, the car barely started again. We drove the hour back home, and I placed the car on a the charger again overnight.

This morning I went out, checked the charger, and the light was green. I started the car, and it cranked no problem, everything seemed fine. I let it idle for a few minutes, and turned it off. (I realize that idling it for a few minutes isn't going to charge it, but I figured that if the battery was properly charged now, it should be able to be started and turned off multiple times without draining it).

My wife went to take the car out today, and it started, but the dash screens were flickering as if it was struggling to start. She was leaving to do errands, so I told her to take the BMW instead, so that she wouldn't get stranded in the Volvo I just checked it again now, and it starts, but the battery definitely seems weak.

So, some questions:

1). I'm not sure what I did to drain the battery in the first place... My daughter and I were sitting in the car playing with the Nav and other car features with the ignition on, but it was only for about 10 minutes. I don't think that should be enough to drain the battery, is it?

2). The dealer that I bought the car from said that it had been on their lot for about 45 days... I'm assuming without being driven much. So, maybe this was enough to kill the battery? But if so, why did it run fine for the last week with numerous starts and short trips?

3). Do these cars have notoriously weak batteries, or weak alternators? Is this a known issue?

4). I called my local O'Reilly's Auto parts and the quoted me a price of $120-170 depending on which "Group" battery my car needs. (Not sure what the groups are). They said that if the stereo has a security code they can't install it themselves because they might lock the stereo. I'm assuming this isn't an issue for me, since the stereo is integrated, right? I was planning on installing it myself.

5). When charging the battery, should I have the negative cable on the negative battery terminal, or grounded somewhere? I know this is an age-old argument across the board with all cars, and I have always gone for the direct terminal connection.

I was reading the owners manual, and under Battery Replacement on page 333 it says,

"The negative terminal on the battery
must never be used to connect a
jumper cable or a battery charger. Only
the ground point on the chassis may be
See page 113 for an illustration and additional

I read that, and thought, Oh, maybe that's why my charger isn't working on the battery.

As always, any advice or suggestions would be welcome.

At this point I'm leaning towards just walking down the street to the parts store and grabbing a new battery. But, if I could somehow bring this one back to life by charging it, that would be ideal.