Battery fail?

[BlindOptimism]

Hi there

First of all, apologies if this is a commonly asked question. I've searched many a forum over the last few days and although I've seen similar problems, I haven't found one that displays my particular traits.

The problem

My Macbook pro 15" early 2008 model won't turn on. I'm pretty sure it's battery related, as I have two batteries and my computer switches on when using one of them. The battery that works is extremely old (I replaced it with the one that no longer works) and isn't a long term solution.

Further Details

Pressing the power button on my Mac results in no response whatsoever. No sound, no display, no fan, no lights, nothing. It's completely dead, as if it's not plugged in. However, the battery does appear to be alive - I have fully charged it (it WAS empty, but successfully charged with the magsafe first displaying the orange light and then the green as usual) and pressing the battery check button displays the full five lights. It appears to be fully charged.

It MUST be battery related, surely, as putting in my older battery consistently turns the computer on. I've tried leaving the failed battery charging over night and I've tried leaving it out of my computer. I've tried SMC and PRAM resets multiple times.

How It Happened

I wanted to turn my Mac into an alarm clock, but I didn't want to leave it charging over night (which I have subsequently discovered is completely safe). I usually switch it off when I go to bed, but this time I tried to put it into sleep mode, to see if that would work. Obviously, the battery drained/died, but I don't understand why it wouldn't come back on.

So that's it. There's nothing really I can do to 'fix' it as nothing I try works and it looks like I'm going to have to buy another one, but I thought I'd tell some knowledgeable experts first and see if I could at least learn why an apparently fully-charged won't turn on my laptop, when an old, dead one will.

Thanks for your time.

 

[Giaguara]

Is it still acting? If you put it to charger, let it charge for a while (say 30 min), then try to power it on... any better luck?
I see you also already have done the SMC and PRAM resets, which is good in this case (just bad for the fact it didn't get it started). The only other things to do would be to fuse it with another battery...
It does sound like the way you have used the Mac over the years has drained and stressed the battery quite a bit. Before the unibody Macs, a typical Mac battery would last around 300 battery cycles (where 1 cycle is draining 100 % and charging 100 % - e.g. 10 x doing a 10 % drop and recharge counting as one). If you can get it once more to power with the battery, or to see the battery with System Profiler, I would not be surprised if the battery cycle count was much higher than 300.

 

[BlindOptimism]

Thanks for replying. It's sorted now - turns out it was the charger. I don't really understand it, as the charger worked on the older battery but not the newer one, but since I bought a new one, I've had no problems at all. I checked system profiler like you suggested and my battery cycle count is 514, so I'll probably have to get a new one of those soon as well, but for now the charger has been a 100% fix.