MacBook Air 2018 13" Battery Capacity

[JSBintu]

Hello,

I bought this brand new MacBook Air 2018 just yesterday, and opened it to use it. I had charged the battery 100% and went over to look at the Battery Health just because I was curious. After some online research and the help of coconutBattery, I have found out the Design Capacity for this laptop is 4381mAh. However, my Full Charge Capacity is shown to be 4339 mAh. Should I be worried? It's only got 1 charge cycle, surely the capacity shouldn't go down that fast?

Note: My Macbook was opened with a dead battery, normally it should have some juice in it.

Hope somebody can help or tell me that I'm worrying for no reason.

Thank you.

 

[ghanwani]

The machine was built in 2/19 so it makes sense the battery was completely discharged. The full charge capacity fluctuates--not sure if this is an issue with Coconut Battery or just the way the battery is.

 

[0906742]

I owned an new Air 2018 (similar manufacturing date as in yours) for like 2-3 weeks and it had the same issue with arriving dead battery. Mine was made in January but battery was from December as in yours, but they do charge battery when unit is being manufactured, so battery date is not the last date it was charged the last time. I already got it in June and it was already empty battery then!

Problem with battery running empty is that it is never good for the battery. Mine also suffered from that it was under nominal design capacity from the start and it just kept weakening all the time. Within under 10 charge cycles and couple of week it was already down to around 4200'ish mAh, is was weakening like 1-2% per week. So I guess who knows for how long it has been sitting in warehouse with empty battery definitely did harm it.

I ended up returning mine, not just only because of the battery but that MBP 2019 1.4 model was released soon after getting my Air and because I got good bargain for it and ended up paying under 200 extra for it, it was no brainer. But I guess if I was going to keep my Air, I would have tried to get one with fresh battery. When battery is new (and you did not lose in the battery lottery, they can be often weak even when new and fresh), you should see Full Charge Capacity being somewhat higher than Design Capacity at least for some time (like in my MBP after over 1,5 months and 24 charge cycles it is still about 2% above the design capacity)
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The full charge capacity fluctuates--not sure if this is an issue with Coconut Battery or just the way the battery is.

It has nothing to do with CoconutBattery, it just pulls the information from MacOS where they all do.