Car is an '04 Audi A6. I go for short drives (grocery store, errands, etc.) about twice a week – maybe ten miles a week on average. Both my wife and I use public transportation for our commutes to work.
About 6 weeks ago, I went into the garage and my car wouldn’t start. The lights came on, though they were a bit dim, but it wouldn’t start at all. Luckily, the maintenance guy in my building was able to drive his truck over and jump start it – and the problem seemed to be over. I was taking my car into the dealer’s shop the next day for another minor problem, so I asked them to look over the battery and electrical system to see if anything was wrong. They looked at it and said they couldn’t find anything wrong with the battery, or anything else that would explain why it had been dead.
So then the car worked fine for the last 6 weeks. No problems starting it up. But yesterday after work, I was going to go pick up my wife, and it wouldn’t start. And this time it was totally dead – no lights, automatic door locks didn’t work, nothing. I had to use the key to open the door – the fob wouldn’t work. There was someone else going to their car in the garage and I asked them to help me jump it. First, I did the jump connection like I read was safe – negative connection (or maybe positive, don’t recall exactly – whatever google told me to do) on the cables to the dead car goes to the engine body, rather than the direct terminal of the battery (with all the other cable connections on the appropriate battery terminals). Didn’t work – no lights, nothing. Then I did the unsafe connection – negative connection of the cables directly on the negative terminal of the dead battery, so a direct connection between the two batteries. This time, the lights came on, door locks started working, etc… but the car still wouldn’t start (didn’t even make the starting noise – just dead, and the lights went out again). And when I disconnected and reconnected, nothing – no lights or anything. So I gave up for the day, and my wife had to walk home.
The car is old and has a few other recurring problems, and I don’t plan to take it into the shop for any extensive work any more. My current assumption is that the battery is totally dead to the point that it won’t take a jump, and I’m planning to walk to a nearby hardware store, buy a car battery, and swap it out. But I assume I still have a slow electrical drain somewhere in the system, so I might buy a second battery, a home trickle charger, and swap them out every few weeks whenever one dies.
But I’m not a car guy by any means, so my assumptions could be wrong. Am I correctly diagnosing the problem? Is my plan reasonable, since I don’t want to do any extensive work?