Let me preach on: my car wouldn't start one morning, most likely a dead battery, but I didn't leave the lights on. I get a jump and go to AutoZone. THey say the battery and alternator are fine. So use the car all day, it starts every time. The next morning, the car won't start. WTF? I get a jump, use the car, but leave it running once I get home. I take a reading with my voltmeter every now and then, and the voltage is 14V or so......just fine. Thus the alternator is fine - that's good. I YouTube some advice, and check for anything (lights that won't go out, etc) but find nothing that would drain the battery. So I completely disconnect both the negative & positive battery leads. I take readings every 1/2 hour over the course of two or three hours. I lose about .1 volt (100 m volts) every hour. So yes, by morning I will indeed be under 12 volts and the car will not start, no doubt. Thus I have to keep it running all night in my driveway. I reconnect the battery and the voltage jumps up to 14.3 within about 10 seconds. Any thoughts? AutoZone says the battery and alternator are fine. No doubt the alternator is fine, since it recharges the battery no problem. But whether with or without the leads connected, the battery slowly loses voltage. Discuss!
How do the terminals on the battery look? And when was the last time you cleaned them? I've had similar problems before and it turned out to be nothing more than dirty terminals. (And once they get dirty, no matter how well you clean them, they'll continue to get dirty.)
Could be an internal short in the battery, or a bad cell. Either one could cause a slow discharge. Try disconnecting the battery and seeing if it discharges, if so it could be either of those problems. If it doesn't discharge, then it could a relay that's not opening and causing a discharge. How old is the battery?
That's what I did - I completely disconnected the battery and got that slow (.1 volt per hour) drain. Is it possible AutoZone didn't catch this when they diagnosed the battery? Regardless I'm going to try to get an appointment with the VW dealership and have them check it out. The battery is 2 years old or so.
It could be a bad cell, not holding a charge. Maybe an internal short or the cell is just bad. It could cause the other cells to drain by pulling the charge from them. Two years isn't that old, but depending where you bought it, it could have sat around for several months.
In a hot and humid environment 2 years is about what you get. South Florida burns up batteries in about 2 years. All the natives about that when I moved there, and it was right around the two year mark that both my fusions lost their batteries, and the same thing with my parents who replaced their cars on their moves to florida. NY I probably got more than 2 years, but those were also older less computerized cars. Still, they can go in 2 years, and perhaps the heat ends up damaging them earlier like you said. It sounds like a swap would be a cheapo fix since the auto-zone people can be less skilled with the tools, or perhaps really busy or lazy and do not want to swap out a battery right now so they just send you away realizing you would go to some mechanic or some tow truck driver who would help you out. I do not know if they get extra pay for doing batteries, but if not it would be a PITA job they could avoid. It is 2 years so a battery swap would be coming soon anyway, and maybe go with a higher grade battery. I would avoid dealers unless under warranty because I have never found one that does not gouge on simple generic things like batteries and parts. I cannot speak of VW, but I have never seen a dealer be competative on pricing with a mechanic or auto-parts store. A mechanic might be the best to go to as long as they do not start finding other things wrong because the battery is generally a cheap fix they do not need a bay for and in some places the work has to fix the problem or else they are on the line for the parts and labor. Check your local laws for that one.
AutoZone can't change out a VW New Beetle batteries. To replace a battery you have to take part of the car apart - a whole exterior section of the car. They don't have the facilities for that - it's that involved. This could be why they said my battery was okay - they can't sell me one anyway. Regardless I can't let my car run 24/7 just because I can only turn it off for a couple of hours at a time. And like I said, disconnecting the terminals won't help - it still slowly drains away.
Do you have a trickle charger? Granted, that would only help for a little while since the battery will just get worse.
If I bag a deer come September you will. That's how I will get it to the butchers. I must admit, it's pretty funny when there are all kinds of trucks parked at the hunting sign - in station and one car......mine. And it's not even a big ol' tuna boat of an early model car - just a Beetle. Anyway, I took the car in to the dealership. Their initial diagnosis came up nothing wrong with it. No shit, that's why I said it's a slow, slow drain. But they are running an overnight test for parasitic current leakage. I will end up eating some vacation time, but what can you do?
Wow, that sucks. If the battery is draining when you disconnect the terminals I would just swap the battery. Your troubleshooting method removed the car from the equation so things being as you say there is a problem with the battery. Sometimes the dealership mechanics do not think properly. I had a saturn that was having some sort of electrical short that was activating it's anti-theft unit and kept it from starting randomly. The source was coming from the remote starter kit that they had installed as some package when I bought it. They were talking all sorts of troubleshooting and repairs and I just asked if they could disconnect the remote start. They huffed and puffed but did it anyway and I never had the problem again. Beware of them doing costly investigation on your dime. Swap the battery and fix the problem. They will charge you up the ass for all that troubleshooting and if for some reason the car is fucking with the battery you are getting a couple of years out of it anyway. Save all that troubleshooting money and get yourself a nice portable jumpstarter and leave it in the trunk for an emergency if you are worried. I think they run about 60-100. It has been a while since I bought one. the good ones work so much better than jumping a car. I know a few tow truck drivers who have them and it is a quick fix that pays for itself real fast. Don't let them screw you on diagnosis or replacing a whole lot of other parts because you disconnected the battery and it still discharged. It is one of the reasons I hate dealership mechanics. They are always finding something that might be a problem and wanting to replace it.
Seriously, just have them swap out the battery. Do not lose vacation time while they chase a problem in the car which might just be the battery anyway. You can pick up the jumpstarter I was talking about at an autoparts store or places like a loves truck stop. The autoparts store guy will probably explain the operation if you need it where at a truck stop you might not get someone familiar with it. I know loves is always having some advertised deals on those things, but there is also TA, Hess, QT and places like that. If you want some help with what to buy find one of the truck stops with showers where the truckers take their big breaks. If it has some repair areas all the better. If you talk it up with some of those guys you could probably find a station mechanic or one of the truckers who could help out. One of the ways I ended up learning things like this is because I pick up a coffee and go bullshit with them for a bit. I am curious about how things work and if one of them needs a hand I just pop in and help out. I also used to do late night shifts at some gas stations in NY. You get some fucked traveler from time to time and help them out, or also talk it up with the mechanics when you get off shift or have some downtime. There is a reason I end up knowing so much and it is because I stick my nose into everything. As long as you show respect and have manners with people in those places they often are happy to help out.
Turned out to be my radio was draining the battery. They had to yank out the fuse in the back (not the fuse in the fuse box the owner can remove). I did not buy another radio though they offered to put in a new one in at way, way too much money IMO. Turns out when disconnected my battery wasn't draining - it's just that the current flowing through my multimeter leads when I checked the voltage made the voltage drain a tiny, tiny bit. That makes sense, I had my meter set on millivolts to detect even slight changes. Sort of like cutting a piece of paper to test the sharpness of a knife - once you cut the paper, the knife is now just a tiny bit duller. There's some kind of scientific paradox explaining that but I can't remember the name of it.
When I brought the car in, the first thing they asked was did I install an "after the fact" radio? Apparently people put in their own radios and miswire them quite often.
