Laptop batteries

  De Marcus™ 15:36 30 Sep 2005

I've got a laptop which the battery has been a dud on for some time (approx year and a half)- i.e. won't take or hold a charge (tried the freezer trick). I came across a site today which suggested a lot of laptop batteries have some kind of countdown circuitry which after a specified number of charge cycles will cease to function. Whether this is done by date and time setting in the bios or an actual countdown clock in the battery they couldn't decide on. I decided to take my bios clock back to 2 weeks after it was purchased and lo and behold the battery is charging! From being stuck on 3% for such a long time and now as I type up to 68% and still going, is they something the manufacturers aren't telling us or is it for our own good, i.e. exploding batteries?

  amonra 16:45 30 Sep 2005

Interesting - - - -What laptop ?
Never met this before, most NiCad batteries die naturally after a short time anyway. Let us know the outcome when fully charged.

  De Marcus™ 17:18 30 Sep 2005

It's a Toshiba Satellite, I'm up to 77% now and the process seems to be slowing, still better than 3%. Whether it runs the laptop after the charge is another matter altogether.

  jack 20:06 30 Sep 2005

NiCad batteries have a 'memory'
That is to say- if it is recharged when only 80% disharged it will 'consider' 80% is 100% so to speak
so you can see the analagy.
The way around this to to completely flatten the battery
In the case of my numerous sets of 4 AA cells for my camera I from time to time put them in a torch and leave it on until there is not a glimmer.
Now how you go about this with a lappie batI would not like to suggest 'cos there seems to be more than simple +/- connections- but I guess some one knows a trick or two.

  ade.h 20:37 30 Sep 2005

Not that it is entirely relevant to De Marcus's original question, but it is a good idea to be careful when discharging Nickel Cadmium cells. If the voltage of each cell (which is normally rated at 1.2v, hence battery packs provide outputs that are divisible by 1.2) drops below 1v it is possible for the polarity to reverse. If that happens, the cells become unusable, so be careful not to over-discharge. Consider using a discharge device that will reduce each cell to 1v, ie. a 12v battery pack will be dropped to 10v.

  josie mayhem 21:06 30 Sep 2005

You would think that they would have a built in discharge setting for Nicad batteries that are used on laptops.

One of my mobile phones had this feature on it, and never had any problem with keeping it's charge! It was my fault that it died! I drop it down the toilet....

  Totally-braindead 22:16 30 Sep 2005

Flushed with success perhaps josie mayhem! Sorry couldn't resist. I'm interested in whether this works for De Marcus™ as I've never heard of this before. Will be checking back later to see whats happened with the charge.

  wee eddie 23:27 30 Sep 2005

Think about the required decision making capabilities of such a device.

How does it differentiate between, an almost complete discharge, and someone who uses the Laptop for 20 minutes on the Train each day and then plugs it back into the mains.

  DieSse 01:56 01 Oct 2005

"How does it differentiate between, an almost complete discharge, and someone who uses the Laptop for 20 minutes on the Train each day and then plugs it back into the mains."

It's not a real memory, it's a chemistry thing - don't ask me to explain tho' :-))

That's why NiCAD batteries suffer from it badly, but NiMH and LIon types don't.

  DieSse 01:57 01 Oct 2005

Good writeup on how to treat LIon batteries click here

  wee eddie 06:14 01 Oct 2005

It was De Marcus™'s "circuitry" that I was querying.

Thanks - That link is to interesting site

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