Battery recharging gets "stuck"?

[taphil]

I've had this problem occur a couple of times now over the past six months...

The main battery doesn't complete the recharge cycle, meaning it charges to 99% but doesn't actually finish - it gets stuck This wouldn't really be a problem because if it occurs, I'd still end up with a practically recharged battery. But I also have the ultrabay slim li-polymer battery, which doesn't get recharged until after the main battery is fully recharged and completes the cycle, after which the ultrabay battery begins its recharge cycle. So what happens is that when I take my laptop to work in the morning, the ultrabay battery is empty and I didn't know.

When this happens, the battery meter in the taskbar remains at 70% (which is 99% full main battery and 0% ultrabay battery). That program just shows progress, so I doubt the actual software controls the recharging process. Restarting the computer, unplugging the AC adapter, turning off the computer, and taking out the battery doesn't fix the problem. I have to actually run down the main battery a bit and then recharge it, after which it will charge to completion and then the ultrabay battery will begin recharging.

Does this sound like a problem with the main battery, which is a Sony by the way? Do you think IBM will replace it easily with a new or practically new battery if I call them, keeping in mind I just called them yesterday to ask for a keyboard replacement?

[cjsuh]

Touched on in another thread, but I think this deserves its own...

I've noticed the same problem with my battery. It charges to 99% and then just stays there. Sometimes it goes to 98% and just stays there. Even when I put the machine on standby, and leave it plugged in, it comes back on at 99%. Anyone know what this is all about?

[Humpa]

I'm not sure if this has anything to do with it, but I remember reading something about the accuracy of battery guages.
For LI batteries, they are supposedly unaffected by shallow charge/discharge cycles. But not so with the battery meter. I read that a deeper discharge-charge cycle is needed every so-often to maintain the accuracy of the meter.

The charge threshold is set at 95% in thinkpads - and the T42's (and R51/X40) have adjustable threshold level in Battery Health settings.

[Humpa]

I found where I read about the battery guage accuracy:
http://www.batteryuniversity.com/parttwo-34.htm

A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery. There is no concern of memory when applying unscheduled charges.

Although lithium-ion is memory-free in terms of performance deterioration, batteries with fuel gauges exhibit what engineers refer to as "digital memory". Here is the reason: Short discharges with subsequent recharges do not provide the periodic calibration needed to synchronize the fuel gauge with the battery's state-of-charge. A deliberate full discharge and recharge every 30 charges corrects this problem. Letting the battery run down to the cut-off point in the equipment will do this. If ignored, the fuel gauge will become increasingly less accurate. (Read more in 'Choosing the right battery for portable computing', Part Two.)

Aging of lithium-ion is an issue that is often ignored. lithium-based batteries have a lifetime of 2-3 years. The clock starts ticking as soon as the battery comes off the manufacturing line. The capacity loss manifests itself in increased internal resistance caused by oxidation. Eventually, the cell resistance will reach a point where the pack can no longer deliver the stored energy, although the battery may still contain ample charge. Increasing internal resistance is common to cobalt-based lithium-ion, a chemistry that is found in laptops and cell phones. The lower energy dense manganese-based lithium-ion, also known as spinel, maintains the internal resistance through its life but loses capacity due to chemical decompositions.

[Leon]

a friend gave me an extra (brand new) battery..... how best to store it long term...freezer?

[Humpa]

Leon, the best part of that batteriesuniversity page is probably this:

Simple Guidelines

* Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory. (In this respect, lithium-ion differs from nickel-based batteries.)
Short battery life in a laptop is mainly caused by heat rather than charge/discharge patterns.
* Although memory-free, apply a deliberate full discharge once every 30 charges to calibrate batteries with fuel gauge. Running down the battery in the equipment does this. If ignored, the fuel gauge will become increasingly less accurate. The battery life will not be affected.
* Keep the lithium-ion battery cool. Avoid a hot car. For prolonged storage, keep the battery at a 40% charge level.
* Consider removing the battery from a laptop when running on fixed power. (Some laptop manufacturers are concerned about dust and moisture accumulating inside the battery casing.)
* Avoid purchasing spare lithium-ion batteries for later use. Observe manufacturing date. Do not buy old stock, even if sold at clearance prices.

I have to think that the freezer would be a poor storage environment, though I'm far from sure. Store in a cool dry place.

[ian]

Store in a cool dry place.

Famous quote that - Travelling Wilburys even wrote a song about it...

[Leon]

well, a freezer IS cool and dry. and if I remember my chemistry, low temperatures slow down chemical reaction (e.g. those that cause battery discharge)..... comments?

[Humpa]

I'd be worried about condesation in the freezer (at the warm side of the cycle). At least I know I would be with my current freezer.

Famous quote that - Travelling Wilburys even wrote a song about it...

... lol
Yes, rather vague explicit instructions.

[taphil]

In my and cjsuh's case, the problem isn't that the battery gauge is off. Rather, the battery recharging circuitry or whatever doesn't complete the recharge cycle, which causes the gauge to remain at 99%. In my case when this occurs, the ultrabay battery doesn't get recharged.

[Leon]

but still, it COULD be the gage saying 99% (possibly incorrectly) and not allowing the switchover to the other battery

[Humpa]

Yeah, that was my point ... It's just a possible theory I threw out there, though.