Chosen Solution
Hi ! I’ve been changing batteries on my macbook air / pro for a while. I usually buy batteries from Chinese vendors on Ebay. I realized the batteries quality varies. Some last quite long, some die very early even though they all look the same (with the usual Apple branding / text on it). Problems generally occur when it’s not possible anymore to send it back to the vendor. Last time I bought one, it worked fine for a month or so, and then the macbook wouldn’t start at all. At first I thought the motherboard died, but I put the old battery back and it was starting again. So is there a way to test the battery upon receiving it to know if it’s going to function properly? I growing tired of buying $40 batteries that only last a few months! Thank you for your help :)
Testing batts is always tricky! Think of it like how do you test an Egg if it’s fertile or not? Letting it sit in an egg hatcher for a few days you can often use a lamp to spot the developing chick, otherwise its cracking open the egg. So how long would you need to run the battery to emulate enough runtime to tell if the battery is good? Now we also have a different issue that is the real killer of batteries! The Cells separator wrappings breaking down. Here the battery is a flat cell design which is like a massive layer cake!
So far there is not real way to test if the separator sheet (insulator) is keeping the anode and cathode gapped correctly. Its a very thin membrane that’s porous for the electrolytic (Lithium Ion chemistry) to work with a completed battery cell. Then needed gear is quite substantial and you need to have something to compare so not something most can do. The best thing I can recommend is to install a good battery monitoring app like CoconutBattery which is my goto, and watching the cycles.
