Design - Lithium

With 24 cells of 40 amp-hour lithium iron phosphate batteries rated to last about 6 times longer than the best lead-acid batteries costing only about 1/3 more the choice to spend a little more on lithium was easy. After about a dozen iterations, the final design kept the balance and weight distribution similar to that of the stock Ninja 250, and met another design goal: all bolt-in assembly with no other changes to the frame. This means that in the future if some other battery format is more powerful, cheaper, etc. an upgrade involves changing out brackets, rather than rebuilding the frame.

All batteries are surrounded by steel framework, either in the form of the motorcycle chassis or their bracket, providing protection if the bike is dropped, though a high speed impact will likely deform the lower bracket damaging the batteries inside. The fully enclosed structure also means that the brackets must be removed to load or unload batteries. Since each battery has a battery monitoring circuit board between its terminals, this layout was also arranged to place the circuits in sheltered areas where damage from road debris would be unlikely.

The upper bracket houses 8 batteries and includes the motor mount. It bolts in to the original rear engine mount tabs on the frame, as well as the mounts for the hanging engine brackets up front. The lower bracket holds 14 batteries and bolts onto the upper bracket. The motor controller, main power relay, fuse and other key components also bolt on to the upper bracket. The two remaining batteries are strapped together and are mounted in the same space as the original Ninja 250 starting battery.