ebuilder said:
I believe your research is wrong. The vast majority of dual hub motor bikes were contrived from a single hub motor bike whereby another motor was added. Almost all have complete redundancy aka a second controller, a second battery, a second twist grip throttle and a second display. This is the most common practice.
https://www.youtube.com/watch?v=SOU4e4SYfug
For a different perspective:
I dunno about the rest of the internet, as I have not researched multiwheel drive systems outside this forum in quite a long time; but in general here on ES 2WD system builders that come here ask about how to run everything from one battery and one throttle (or PAS, etc). What they actually build after asking and being pointed to the various builds like that, I don't know.
I've done it both ways, and found that it is much simpler to use and control when a single control input runs both drive systems, so that is what I use now. There are moments when it would be useful to have independent controls on the trike (separate R and L) but almost always it's easier for me to use just one PAS or throttle to run both of them. (I have thoughts on a switch-in control to independize them for certain situations, I think over in my Nano Tidbits thread, but dunno when I'll ever get around to that...which is how much I need them separate.
).
I've always used a single battery, though, except during certain experiments, simply because the average load on one larger battery is easier on it than the potential higher load a single one might see under some conditions, and because it simplifies the electrical system.
There have been a few independent-battery systems, but many (probably most) of those here on ES use just one to power all the motor systems.
Redundancy is the only really big advantage of independent batteries, so if that's not a system requirement for a particular application, it can be built either way; one bigger battery can see less load on it than each independent one would see, especially if the system is using independent control inputs, and for most situations only one motor is used, so it's peak load on it's separate battery is higher than would be the case if it had one larger battery. (peak load of both motors on separate or unified batteries would be the same either way).
Depending on range needed (for cases where battery size isn't determined by capacity but rather by what it takes to handle a certain current load), it may even be possible to use one larger battery instead of independent batteries, where the larger one is not twice the size of the others, only because the smaller independent batteries are made of cells that cannot quite handle the full peak load of one motor long enough to do what it needs to when running by itself...but the larger battery could, especially if with two simultaneously used motor systems the load is either less or lasts for less time (such as accleration from a stop to cruising speed).
Anyway...there's a number of ways to create multimotor systems, and it depends on the specific application whether each part is better off independent or unified or linked.
(Completely aside from all of the above and not relevant to it, just an info tidbit: old brushed motor systems can do 2WD with two motors but only one controller and one battery and one throttle (or other control input) if it is desired. The motors can be seriesed or paralleled on the output of the controller, depending on the mode of operation desired and the components chosen).