Marty, it can be very time consuming to learn things using a subject based learning method such as buying a text book, and starting at the beginning. Plus, you are going to learn a lot of stuff that you might not need to know.
I'd stick to mostly a problem based learning method, ie learn only what you need to know based on the problem that you are trying to solve.
There is also a grey area where you can create your own problems, and then learn the answer. Example, pretend that you need to double your ebike range....then go out there to find the answer and an explaination.
google can be your friend, and I'd have to say that basic electrical theory can be gained by reading wikipedia. or just ask a question on this forum. I'm an electronics technologist, and I get the impression that there are several engineers on this forums.
Also, there are several guys that just know their stuff really well. They are the experts, I look to them for advice,too.