How does a starter motor change polarity?

[Dwight]

I always disconnect the negative (only) cable from my battery (boat/outboard motor) when I bring it in. Yesterday, I connected the negative cable back to the post, tried to start and the starter would spin but (after MUCH investigation) I discovered that it was spinning in the wrong direction. I disconnected/reconnected the negative cables and, voila, it started spinning correctly. ?!?
This is an older motor (circa 1991/1992) so the starter has brushes... not rare earth magnets. I can find nothing online about it except one forum telling a user with the same problem that it can't happen. Any answers out there?
2 weeks ago

 

[volvopaul]

Hi I have come across this before, if the centre part where the magnet is , has been turned around the motor will rotate the opposite way, made this error one on my ride on mower!

 

[Firefly625]

sorry, off the point...but once had a vehicle bought into us on a breakdown truck that the customer had (after having a completely flat battery), recharged for a few days but couldn't work out why it wouldn't start and starter motor sounded odd. He had not disconnected battery from the car and had just put battery charger cables to wrong posts. In so doing he managed to completely change polarity of battery...& starter motor was spinning backwards... its amazing what else he damaged in the process... not recommended....

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Oh! That was my 1K