Charging empty car battery but battery shows as full??

Hi, my apologies for the sort of double post. I have a 300D from 1977. The battery is dead - I came to this conclusion by noticing that the lights became
increasingly dim and I couldn't start the car at all. Of course, I tried to play a cassette tape and the music slowed down progressively. So I am trying to charge the battery full again, a battery which was first used in April 2000 and says it has 72 months of life from that time.. oddly enough, the battery charger shows it as full - I know the charger works because I successfully used it to charge a minivan a little while ago. What might be going on here? I think the reason my car's battery went dead is because I haven't driven it in quite awhile over the winter months.
Thanks a lot and thanks to Alex Hemmerich for helping me get the hood open ;)
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a lead battery, car battery, needs to be charged all the time to stay alive... dead lead acid batteries...deeply discharged for longer periods of time will desturct themselves...
buy a new battery and keep it charged... if you dont usw the car for a longer period of time....have the battery charged from time to time... and in winter...unmount and disassemble from car and keep in heated enviornment with controlled charging from time to time
alex

battery is dead - I came to this conclusion by noticing that the lights became increasingly dim and I couldn't start the car at all. Of course, I tried to play a cassette tape and the music slowed down progressively. So I am trying to charge the battery full again, a battery which was first used in April 2000 and says it has 72 months of life from that time.. oddly enough, the battery charger shows it as full - I know the charger works because I successfully used it to charge a minivan a little while ago. What might be going on here? I think the reason my car's battery went dead is because I haven't driven it in quite awhile over the winter months.

;)
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Thanks Alex... but surely, the battery couldn't have died so quickly on me? I suspect it was a little over a month when I last drove it... and I don't think the damage could have been so great? I should still have life left in this one, but I'm still wondering: what does it mean when I try to charge the battery but the battery shows up as full in the charger? That it in fact is dead? It can't be totally dead since the headlights still come on (dimly) although it won't start or anything like that. Argh. Thanks for the good advice.
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Some bad batteries can be charged to the full voltage potential and still be unable to deliver the normal amount of current since the battery has a high internal resistance. One way this can happen is if the plate in one or more cells has essential corroded to the point where a large area of the plate has dropped off and is no longer part of the electrical circuit. Attachment of a charger to this type of defective battery may still be able to charge the battery to its full potential over time, but the lack of full plate area will prevent the battery from delivering a normal amount of current. In electrical terms this is characterized as having a high internal resistance.
Of course, as suggested in another message, one should be certain that the high resistance is not introduced by way of bad corroded post connections.
Dan

me? I suspect it was a little over a month when I last drove it... and I don't think the damage could have been so great? I should still have life left in this one, but I'm still wondering: what does it mean when I try to charge the battery but the battery shows up as full in the charger? That it in fact is dead? It can't be totally dead since the headlights still come on (dimly) although it won't start or anything like that. Argh. Thanks for the good advice.

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The charger indicates that the 3 or 4 year old battery is fully charged BUT the car's lights, stereo and starter fail to operate?
Remove the battery and take it to the store that sold it and guarantees it for a LOAD TEST which will probably determine that the battery is, in fact, dead.
The other explanation is that the connections TO the battery are loose and / or corroded and so a fully charged battery couldn't power the starter etc. If the terminal posts are not clean and tight they should be cleaned and tightened.
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You have a four year old battery that is suspect and very likely bad. Why fool around and waste time on something that doesn't cost a lot and is easy to replace? Even if it's still under some warranty, by the time they pro-rate it, you're not going to get much, if anything. And if you fool around and think it's ok and it dies again in the middle of nowhere, what's that going to cost? Just buy a new one.

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thank you, well said. we should focus on the major things...not fooling around with dead batteries...where everybody knows.. a replacement is cheap, manditory sooner or later and is easy to do....
alex

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Put it back in the minvan then :-)
You might have killed it if you left it in a discharged state in the very cold for a very long time.
The other possability is the cables. Take them off and hrow them away and fabricate new 00 gauge cables. Clean the the connection points scrupulously and reattach.
Battery chargers can not always be trusted to show a full battery, have it load tested, If it passes, do the cable thing, if it fails you need a new battery. I'm pretty sold on Optima, but Interstate is a good second choice (it just won't last as long).
A good rule of thumb is to throw away any 5 year old battery in a diesel no matter how well it works, (unless it's an Optima) as you're relaly living on borrowed time after that, and that's assuming the battery had been propely maintained which yours apparantly wasn't.
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Thank you Alex, Dan. T.G., Chet, and Richard for your help. It really helped me to learn something about this car, as frustrating as it may be.
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