Macbook Air Battery issues... thoughts?

[manlymatt83]

Hi all,

Three year old MacBook Air (early 2014).

*IF* and only if I can get the battery to charge up to 100%, it charges veryyyy slowly. But once it's at 100%, it drains normally until 47%. Then the computer becomes very unreliable on battery power -- normally just shutting itself off hard. If I can get it to turn on without plugging it in, it'll usually shut off a few minutes later randomly even if the battery is still around 45-50%.

Most of the time, I have to use the laptop with the wall charger. For example, right now I have it plugged in. The battery says 47% but the message "Battery is not charging" appears when I click the status icon at the top right. If I were to unplug the laptop from the wall right now, it would immediately shut off -- no clean shut down.

However, yesterday I was traveling and plugged the laptop in at a Starbucks and low and behold it went from 47% up to 95%... same charger. Seems to work sometimes, not others.

Any thoughts on this? I hesitate to say it's the battery that needs replacing because the battery charges sometimes and not others, and the health of my battery is "good", cycles only 475. I have also tried multiple wall chargers so I know the problem isn't that either. If this is a motherboard issue, I'll probably just grab a new MacBook Air.

Thanks!

 

[Valantar]

That sounds like a bad battery to me. 475 cycles is slightly low for an outright failure, but it's not entirely unreasonable. Your problem is typical of worn-out Li-Po/Li-ion batteries: instead of "gracefully" lowering their voltage from ~4,2V when full to ~3,4V when empty, output voltage suddenly and unpredictably drops too low for the connected hardware to operate. In effect, the battery disconnects, immediately and without warning, resulting in immediate shutdown. I've seen it in hundreds if not thousands of smartphones through my job - the exact same symptoms - and a battery swap always fixes it (as long as charger faults have been ruled out).

Battery "health" gauges are notoriously imprecise. It not accepting a charge is far more indicative of its health, as your charging circuits are telling the BIOS/OS that "hey, we've supplied X voltage for X minutes an output voltage isn't rising the way it should, something is wrong here."

 

[corkyg]

Sorry - posted to wrong read.

 

[manlymatt83]

Thank you! I'll try getting the battery replaced.