Getting ready to sell car, but battery keeps dying. What's the deal??

Question

So in 2004, my dad won me a 1998 Mercury Mystique as my first car. Near mint condition, very comfortable and a smooth ride. I loved this car to peices. But last year the tags and insurance expired, and it sat for a while, and even still continues to sit. So around November, I decides to add a CD player. Getting the radio installed was hard enough, as my pap's and I had to damn near dissesemble the dashboard just to get to the wires and install a harness. Once we finally got the radio in, we jump-started it and that was that. Ever since then, I have to constantly jump-start the car, and leave it running. Now before anyone says anything else, I already took the radio back out and jumped it, to see if that was the problem -- surprisingly, it wasn't. Despite the fact that I could get into legal trouble, I even took out for a spin around the neighborhood, just to see if actually driving it would help. The next day it's dead again. Like I said, I plan on selling it, but not like this. Help?

And please, none of that jazz about me needing to "buy a Japanese car" or about this car being a Mercury 'Mistake'. First of all, I don't care for import vehicles and the Mystique can be a very reliable car, when you take care of it and put in the work to make it so. I've just run into some issues.

I did actually put the radio back in. I forgot to mention that. I eventually went to buy a portable jump-starter, so I can at least get it to Autozone or Jiffy Lube.

Answer 1

if a battery sits for too long the connectivity inside the battery dies leaving you with a bad battery. now, when the car is running the alternator is charging the battery but since the battery is bad, it will not hold this charge. the reason your car runs fine once you start it is due to the fact that the car gets its power from the alternator, the only time the battery is actually used is on start up or when the ignition is in any of the two accessory modes. for example the car is not running but you are listening to the radio. i would definitely replace the battery and see what happens from there. since the car runs fine that pretty much rules out the alternator being bad. one other thing you could check is the tightness of the battery cables to the battery but my bet is that those are OK. i wish you the best

Answer 2

Have you checked to see if you have a bad cell in your battery? Batteries only last so long. Perhaps it is time to get a new one. You can take either your running car, or just the battery to Autozone, and they will test the battery for free. If you drive in, they will also check the alternator, while it is on the car. If the battery is ok, then perhaps your alternator is bad.
One last thing that people don't always consider would be the cables. Perhaps you negative/ground cable isn't truly grounded. This would cause your battery to drain. Often the cables even look fine on visual inspection, but internally, they can be corroded.
If the battery and the alternator check out, then consider the cable. Also, check to make sure that you have totally grounded your new deck, as this could also cause problems.
It should be a simple fix either way. Good luck.

Answer 3

The battery could be bad. When they go bad they do just what you are describing. You can jump start it, run it and the next day the battery will be dead. It could also be something in the car that is draining the battery. Dome light left on etc. Chances are if you caused a problem installing the radio it would be a short and blow a fuse or burn a wire. I would have the battery checked. They usually last 4-5 years. If they are left sitting with a low charge they will die quicker.

Answer 4

Take and buy you a test light and disconect the battery neg terminal and connect one end of the test light to the charged battery and the other end to the cable. Start pulling fuses until the light goes out (or really dim) there will lie your problem. You can also use a DVOM to check. BUT the computer does have a keep alive memory that will pull a small amperage and about .02 volts. THIS WILL drain your battery after about 30-45 days even with a good battery.

Answer 5

You didn't say if you put the radio back in the car. If you connect the radio to a power source that is always hot, such as the cigerette lighter, it will have constant power. Does the radio turn on without turning on the ignition? If it does, this is draining your battery!!! Like everyone else said, also have the alternator checked and the battery cells checked. Good luck!

Answer 6

You may need to have your battery tested or charged. Just by letting the car run for a little bit is not going to charge your battery enough to turn your car over all the time. And if you put a new battery in it and it works for a little bit then does the same thing, your alternator may be pulling all the juice out of you battery.

Answer 7

Generally when a battery dies there is no charge from the alternator to keep it charged. Here's a test, put a new battery in and when running remove the negative battery cable. If if suddenly shuts off then you have a bad alternator.

Answer 8

sounds like a bad battery. 1st. thing to do if you have a battery charger is put a full charge on it at slow charge rate. then check it with a battery load tester. also after jump starting, you can connect a volt meter to see if your alternator is putting out 13-15 volts. its possible your not running it long enough for the alternator to fully charge the battery.

Answer 9

i own a repair shop,and id have the alternator checked on it just so i could rule that out,and also have the battery checked,and if this checks good start looking for a loose or bad ground wire on it,its possible that when you had the dash out of it ,and all that stuff disconnected,that you might have left something loose on it,we all do it sometimes.but check around the battery real good for a dirty cable or a bad connection,that's the most common cause for what yours is doing,good luck,i hope this help.s.

Answer 10

if the car sit for awhile and was not started ..the cells in the battery are dead try repalcing the battery and have a mechanic check the alternator output power..