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I bought an iPhone 7 plus motherboard but I don’t have a 7 plus battery I read that the 7 plus battery fits in the 6s plus does that mean the 6s plus battery fits in the 7 plus? I don’t need it to go inside the phone and stay there I just need to connect to the motherboard to see if it works. Are the connectors different? Is it going to blow up? are there any batteries besides the 7 plus that have the same connector as the 7 plus?
If you have around an iPhone 7 battery you can use that one to try out the board, despite different size, connector is the same. Unfortunately I don’t have any 6S plus battery to check, but I can confirm the 6S connector would not fit.
It should work, the batteries from the 6 plus, 6s plus and 7 plus all fit vice-versa, it is good enough for testing.