Hardware Charging terminals

[NekoMichi]

Are the polarities on the charging contacts the same way round on an O3DS and N3DS XL, or has Nintendo reversed them? I have a charging cradle for an O3DS and plan to take out the insides and mod it to be a universal O/N3DS/XL charging station.

(I'm referring to the two metal contacts either side of the power socket, and not the contacts inside the socket itself.