New Battery, But Only 99%?

[bowjest]

The battery in my MBP was diagnosed as faulty a little under 2 months ago (the MBP was purchased in November 2008) and I was given a new battery off the shelf at an Apple Store.

I've just been charging the battery up again and noticed that although the light is green on the magsafe, the percentage meter shows only 99%.

Here are my battery details:

Battery Information:

Model Information:
Manufacturer: SMP
Device name: bq20z951
Pack Lot Code: 0000
PCB Lot Code: 0000
Firmware Version: 002a
Hardware Revision: 000a
Cell Revision: 0100
Charge Information:
Charge remaining (mAh): 4595
Fully charged: Yes
Charging: No
Full charge capacity (mAh): 4647
Health Information:
Cycle count: 35
Condition: Normal
Battery Installed: Yes
Amperage (mA): -3
Voltage (mV): 12499

Is 35 a bit high for the cycle count if the battery is only a couple of months old? Can someone give me a link (or an explanation) on how cycle counts grow and how best to manage my battery? It would also be helpful to understand the values "Full charge capacity" and "Charge remaining".

To date I've always charged it to 100%, then unplugged and used the MBP until it's very low, then charged again. Once a month I drain it all the way down until it hibernates, then I leave it the recommended 5 hours, and then charge it again to 100%.

I can't see how it's climbed to 35 cycles so fast and why it's now only showing 99% after being fully charged.

Thanks.

[simbalala]

To date I've always charged it to 100%, then unplugged and used the MBP until it's very low, then charged again. Once a month I drain it all the way down until it hibernates, then I leave it the recommended 5 hours, and then charge it again to 100%.

You'll wear the battery out prematurely doing that.

There's no need for complete discharge cycles with Li batteries. Just charge it whenever it's convenient and you've got some stationary time, don't worry about how full it is when you start to charge.

[DeltaMac]

The charging system will not charge your battery until the charge remaining drops below 95%. Your's, at 99%, will show green. That does not indicate 'fully charged', but simply means 'not charging'. Run on battery only until you drop below the 95% level, then the battery will charge to 100%, if you let it do that.
Your Charge Cycles are full discharge/recharge cycles. If you continue to treat your battery that way, then the charge cycles will count up very quickly.

[bowjest]

Thanks Simbalala and DeltaMac for your replies, but I'm confused.

What should I be doing to get the best life out of my battery? The guy at the Apple Store said that running from mains power all the time with the battery in the MBP would limit the battery life.

Are you both saying I should do just that - leave the battery in the MBP and run from the mains power adapter full time even when the battery shows 100% charged and only run from battery power (i.e. unplug the mains adapter) when absolutely necessary?

Please note that this isn't one of the very new MBPs with the 7 hour battery that can't be changed by the end user. This has one of the easily swapped out batteries.

Thanks

[simbalala]

Depends on your usage.

If you leave it plugged in a lot but do take it out (off mains) from time to time that's enough to “exercise” the battery. If you never take it off mains but basically use it as a desktop machine it might be better to actually take the battery out but then you're susceptible to power outages unless you're on a UPS.

I'm on a UPS and I have degraded a battery by leaving it on charge non stop but it took five years.

[Giaguara]

Some more notebook battery tips http://www.apple.com/batteries/notebooks.html

[bowjest]

Thanks.

I'd say I use it more plugged into the mains than not, but do take it off the adapter a good bit just because I was given the impression by the guy at the Apple Store that I needed to do that to "exercise" the battery to make sure it would continue to charge correctly.

So, just to confirm: I can safely run it for hours on the adapter with the battery in it, but take it off the mains for an hour or so from time to time just to keep the battery in good shape.

So in future, I can just keep using it as above and not rack up too many cycles?

Thanks for your help.

[simbalala]

So in future, I can just keep using it as above and not rack up too many cycles?

That sounds good.