How long will a MB battery hold its charge for?

[MST]

I have been thinking about getting myself an extra battery for my MB so that I can use it for longer when I don't have access to a power outlet, but I've been wondering how long an unconnected battery would hold it's charge for, can anyone shed any light?

 

[GGJstudios]

I average 4-5 hours on a charge.

 

[Scepticalscribe]

I average 4-5 hours on a charge.

My MBP averages much the same, 4-5 hours on a charge. Cheers

 

[MST]

Thanks for the responses, but what I really want to know is if I fully charge a spare MB battery how long will it hold that charge for before I connect it to the MB?; I got the impression that your response was stating your average battery life, apologies if this was not the case.

 

[clevin]

depends, screen brightness, wi-fi are all big drain, you can get anywhere from 3-5 hours with normal usage.

battery also degrades through time. especially at elevated temperature.

Thanks for the response ggjstudios, but what I really want to know is if I fully charge a spare MB battery how long will it hold that charge for?; I got the impression that your response was stating your average battery life, apologies if this was not the case.

ooo, it will hold for years.

But if you were to store a battery for a lengthy period of time, you might want to keep it at 40% charge, and in a cooler environment.

 

[misterredman]

Taken from here:

http://www.apple.com/batteries/notebooks.html

Long Term Storage

If you don’t plan on using your notebook for more than six months, Apple recommends that you remove and store the battery with a 50% charge. If you store a battery when it’s fully discharged, it could fall into a deep discharge state, which renders it incapable of holding any charge. Conversely, if you store it fully charged for an extended period of time, the battery may experience some loss of battery capacity, meaning it will have a shorter life. Be sure to store the ejected battery at the proper temperature. (See “Notebook Temperate Zone.”)

 

[iToaster]

It's generally not recommended to leave a battery unused for long periods of time without use on a full charge, but the charge won't go down to zero easily in a few weeks. I have an unused PowerBook battery sitting around (as it needed a new battery) and every once and a while I'll pull it out to check on it. I pulled it out at 100% and haven't used it yet since the beginning of April. As of now the LEDs on the bottom indicate an almost full charge (4/5). I'd say it wouldn't be wise to leave one battery unused for a long as it would have an effect on its overall health, but one cannot deny the advantages of a second battery.

 

[MST]

Excellent! Cheers guys

 

[DoFoT9]

a second battery is an excellent idea.

i have two and use them on a rotational basis because im at uni all day long. i have my newer battery as my "good" battery which i completely use everytime to keep it healthy. my other battery i use as a "whatever" battery and i recharge it whenever because it doesnt need to be healthy.

the battery will probably hold its charge for years.. however its said by apple that if your gonna store it for more than a few months reduce the batteries charge to 50% so that it doesnt damage it.