The idea is to have a simple module that allows you to swap out battery packs. That opens up a whole bunch of possibilities… Obviously, you can have a few packs around that are fully charged and you can switch out like a cordless drill when you need to. Something like this is particularly suited to, say, a trail bike or race bike, where you can throw a bunch of packs in the truck and head off to the pit for a heavy day of riding. There’s a little more to it, though.
You can build a few different types of packs. You have your ultra-light lipo pack, you have your heavy-duty commuter pack. You’re either tailoring your battery chemistry to your riding for the day, or you’re simply using your available batteries, without mixing and matching.
You can also build a few different types of bikes, and use the same pack. Since the batteries are by far the most costly investment, by standardizing on a module design you can have one or two packs and use them in any number of different builds. After a long week of commuting, pop the pack out, slap it in the dirt bike and tear up the trails on Saturday morning.
One more thing… you can easily add capacity to a bike by simply adding modules. Since you’re charging and balancing each pack individually it makes it easier to balance than having two built-in packs that are paralleled for more capacity.
Here, after several years of waffling and researching, not to mention trying out various bracket assemblies and buying every known type of box or enclosure that seemed to have any chance at all of being converted to a module (including milk crates), is what I’ve come up with.
The basic design is a tray. Here’s what the battery side of it looks like:
When you release the latches, you slide it out, like this:
The back has a large Anderson high-current connector mounted, for now, on the frame side of the module. At the moment I’m keeping it so that you have to manually pull the connector out when you pull the tray, but the plan is to have that mounted to the tray, making it a complete plug-and-play assembly. Here’s the back, in the closed position:
And a detail of the final design of the spring-loaded latch, with the Delrin, uh, hole things for it:
As you can see, I’m still working on the final fastening, but v2.0 is going to be tigged up, without a doubt.
I’m waiting before I start cutting up the tabs on my frame – a mandatory “cool-down” period, required by law before taking a sawzall to a motorcycle, but in the meantime I played around with positioning, loaded with a few of the Turnigy hard case packs I’m running at the moment.
Here’s the basic front frame mount:
…and, the belly mount.
The capacity of the first pack I’m aiming at will be in the 2.2KWh range, with 30 of the Turnigy 5Ah 4s packs. That’s three layers of ten, which should be no problem for the tray to carry. The belly tray, at this stage, is not really going to be part of the plan, but one option would be to run two 20-pack modules, for a total of around 3KWh.
The next step is to trim out some of the tabs on the frame, and make the mounting tabs for the bracket. The first pack I’m going to be working with will be a “micro-pack”, only 15 Turnigy hard-case 4s packs, so watch for the details on how that gets attached… stay tuned!