Is there a way to externally charge my battery?

Hello,

A few months ago I spilled some water on my Macbook Air (Mid-2013). Since then, it has not been able to charge. I've had the battery replaced, and the new one also doesnt' charge up, so its not an issue with the battery. I brought it in to be looked at, and they concluded that its something to do with the logic board not recognizing the MagSafe adapter. So basically, the charger and battery both work, but the connection between the two has been damaged. Since then, I've been keeping it on the charger all the time (while it doesn't charge the battery, it at least prevents the charge from going down--when I had my first battery, I let the charge get to zero; when that happened, I always had to power the laptop using safe mode because the battery was that dead; this was super inconvenient for me). I'm wondering, is there a type of charger that I can buy to charge just the battery outside of the laptop? I know it will be a pain to have to remove the battery, charge it up, and then reinstall it every once in a while, but honestly I only need a full battery without the outlet once in a while. Aside from that, I'm happy leaving it plugged in until I can afford to buy another macbook. I've looked online for such a charger with not much luck. The only things I've seen are external battery packs, which still rely on the actual charging port to be able to charge the laptop. Any thought or suggestions would be greatly appreciated!