gman959 said:
We are trying to make an all in one rear bike hub with all the components inside the wheel.
If you really want to put everything in the motor (batteries, controller) you just need a bigger space inside. You could look for a used BionX D series motor, which has a fair bit of space inside, and use a very tiny controller and very small capacity battery. Look around the forum for titles with BionX and there are a few threads that have some internal pictures of it.
However...it gets hot inside the motor, especially with the controller in there, so this will degrade the batteries faster than normal. As long as power is kept low, then this will help reduce the waste heat inside, but there will always be some.
There are also motors that already ahve the controller built in, like the GoldenMotor Magic Pie series. But there's not much space left for anything else in there.
Another option is using a completely separate hub in the other wheel to hold the battery, like the TidalForce bikes did. You could take a second hubmotor and cut out the entire stator except for the (usually six) supports on the axle, leaving only those and the axle in the middle with bearing support for the side covers, and even take the magnets off the rotor. Then build a frame for the battery that fixes to the old stator supports that fits inside the rotor and covers. You'd get a lot more space inside (though still not very much) for batteries that way. You could make new covers that extend the space available, if they still fit within the fork or frame of the bike.
Our current issue is that most commonly available motors have the coils on the stator instead of the rotor like we need.
All brushless motors (which are what is used these days for hubmotors) will have the coils on the stator. If they didn't, the wires would get all twisted up as the rotor spun, and you wouldn't get very far.
If you used brushes instead of wires to get power to the coils, then it woudln't be a brushelss motor, but it can be done. Is just wasteful of power and makes more heat from the brush arcing. That arcing can also cause FET failures in the brushless controller sometimes.
You could use an old brushed hubmotor, but it will generate more heat inside, and I don't know of any old brushed hubs that had any free space inside.