Here are some pics of my G1 mod.
Added new 36 volt controller.
Currently using 3 12Volt 4.5 Ah SLA batts,
but will soon be trying out 2 18 volt LiFePO4 batts from Dewalt packs.
The big button is now a throttle kille switch.
I reduced the spring tension of the throttle, so it doesnt spring back,
I like it that way, so I can keep a constant speed without holding it in place.