I know how to start a lot of aircraft

Must've been something similar you watched, maybe some kind of "how-to" video, cause I've had similar instances where I watched say, the "history of hamburgers," and forever after I get all kinds of cooking video suggestions.
Okay, since we're on the subject of starting aircraft, I seem to recall some older models of the F-15 (and probably other fighters also) didn't have a master battery, but instead, a hydraulic accumulator. Pulling a handle in the cockpit would release the accumulated hyd. fluid into a Jet Fuel Starter, similar to an Auxiliary Power Unit on a civilian jet, except, it only starts the main engine, and does not supply electrical power. Once one engine is up and running, it's generator will supply electrical power, and it's hydraulic system or bleed air can be used to start the second engine. I just thought that was interesting coming from the civil aviation world how I guess batteries and external power aren't reliable enough when you need to scramble in five minutes, and an APU is just too much added weight and something else that can fail and needs to maintained.