I see the merit in having a battery source for charging your phone while away from an outlet, but odds are if I don't remember to charge my phone I won't remember to bring that backup either. One of the few things I rarely forget is my Klean Kanteen thermos. The hope was to build a charger that would fit inside the lid without adding too much bulk. You can modify the CAD file since it's a public file in OnShape, so if you want to make another type of lid for a Klean Kanteen, like one with a place to store your keys and a bit of cash, you can easily do that.
An issue I'm having with the charging unit and 9V battery combo is that my battery has to be basically 100% full in order to charge correctly. I'll probably try and swap out the 9V for a stack of some slim batteries I have from an old camera. Or maybe I'll try a different charger as well, something with a single USB port.
Here's the link to the OnShape file. I think you need to create an account in order access it.
Step 1: Materials and Tools
Here's what you need for this one
Step 2: Remove the Plastic Housing From the Charger
First you need to break open the charger and get rid of the plastic housing. I carefully used wire cutters to break it apart at the seam.
Cut the spring close to the base. You can also de-solder it, but there's no need. I also left a but of the black wire, but you could also de-solder this since you'll be attaching the 9V battery clip.
Step 3: Attach the 9V Connector
Clip your 9V connector so the wire is about 2.5 inches long. Solder the red wire to spot where the spring was, and the black wire to the black wire on the charger.
Step 4: Cut Out the Silicone Gasket
Print out the template, carefully cut it out, trace onto your silicone, and then carefully cut that out. It needs to be as circular as you can get it because it's a tight fit and you don't have a lot of room for error if you want it to fit around the entire lip of your bottle.
Step 5: Insert the Charger
Insert your charger and apply some glue to hold it in place.
Step 6: Pop in the Battery
You'll notice my lid looks a little different from the CAD file. I made some tweaks so I could attach a lid, but I didn't have access to a 3D printer in order to reprint. In the future I hope to make a top that snaps into the lid and is easily removable so you can charge/replace the battery as well as store a short USB cord inside.