Chosen Solution
Anyone still know a source for batteries for this system? PowerBook G4 Titanium Onyx - Model M8407 / 550 or 667 MHz G4 processor
Sadly, no one is producing new batteries for this older model, you might find a used one but given the age factor I doubt it has much life left in it these early 55.3-watt-hour lithium-ion batts are not as good as todays. The Apple P/N for them is 922-4631