My MacBook Air will not keep charge unless it is plugged in. However it started right after I spilled some water on it. Went in through the Trackpad and keyboard. I thought it was completely dead, but I then plugged it in and it turned on. But it does shut off when you unplug it. If I keep it plugged in, it will not run certain games as it will get too hot and shut off. Everything works fine, Except for the battery. It only charges up to 20% and the status of the battery is "Replace Now" I suspected that maybe it was just the battery and nothing else was wrong, but I went to the apple store and they did a quick check and they said that I am lucky it even still turns on because of all of the damages. They also said it will take as LITTLE as $800 to fix it. They claim it is more than the battery. But I suspect that battery replacement will fix it. Maybe not completely but at least to a point of it being semi functional. But what do you think? Is it just the battery? Or something more?
closed as primarily opinion-based by user3439894, JMY1000, Scot, Tetsujin, IconDaemon Jan 14 '18 at 19:24
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This is typical when the current isn’t enough to run the computer.
If you hadn’t had liquid damage, I’d recommend the following:
If you think of a battery storing electrons as a tank stores water - the current is how much volume can come out of the tap. The voltage is the pressure at which the water exits the tap. The battery being “full” or charged is simply the total volume in the tank being “full” regardless of how much pressure and/or volume can come out right now.
Take it in for service or plan to replace the battery would be the logical next steps when your computer doesn’t work with the battery it has.
Since you have liquid damage, I wouldn’t spend any money on the battery since corrosion is likely and you should either pay for a total rebuild of this Mac or keep a good backup until it no longer works at all and replace it.
Like the linked question - it’s not clear if your battery is the problem or your logic board is pulling too much current or has other problems. Liquid damage can do that - break all sorts of things or multiple sorts of things. The liquid also could be totally external and no damage whatsoever - you have to open and inspect all the parts to know and that’s about an hour of trained technician time in most cases to open / look / close everything.