Haven’t been on BLF for a while……so thought I’d share one of my recent projects. It’s a DIY Wooden USB Mobile Battery Pack that uses 2x NCR18650B 3400mAh in PARALLEL to give a total capacity of 6800mAh. It has USB Output 1A and USB Input 1A (for charging Li-Ion - 500mA charge per cell since parallel).
Pictured left: 2-Cell version made from scrap timber, plywood & a bit of Tasmanian Oak (small long-square bits are tas oak) stained with Jarrah, finished with 2x Tung Oil coats.
Right: 2-Cell version made of Tasmanian Oak & Plywood, stained with Golden Teak, finished with 2x Tung Oil coats.
Battery Pack charging an Apple iPhone 4.
Showing the internals of the battery pack. Visible is the battery holder, NCR18650B batteries and the USB Boost Converter output and Li-Ion charging circuitry.
Pictured from bottom to the top: Apple iPhone 4, 2-Cell Battery Pack Final version (aka. Orange), 1-Cell Battery Pack Prototype.
I’ve produced a prototype version before this and have tested this final version for about six months now. All works fine. Uses the onboard USB Input Li-Ion Charging circuit to charge the batteries in parallel. It charges the cells at 1000mA, that’s 500mA per cell since they are in parallel. However the charge termination voltage is a bit high, about 4.20-4.25V (still within li-ion spec). I’ve tested the protection module and it will stop Li-Ion discharging when the voltage drops to ~2.45V (2.5V is minimum voltage for NCR18650A/B). Works perfect! Let me know if you guys would like a build-log/tutorial or more info.
No worries! Always great to inspire others, never know what awesome things you could come up with! I generally make my own wooden cases because there is more customizability and I have very good experience in woodworking.
Sure! I can make a tutorial/build-log kind of thing, as I’ve already have pictures and a 3000-word engineering report for this project. I’ll look into doing it after my final high school HSC exams (in Australia, that’s the final secondary school exams before university). I’ll try to get started on it next month Also I’ll have to note, to get the perfectly even/square sides and round edges, I used a disc sander to do that. But you might be able to do it with a cheaper belt sander, but possibly by hand but that will take awhile depending on how uneven the sides are. Besides that, its mostly hand-tools from there.
That looks nice and old-school. I have been hobbying with wood for years before I got into flashlights. Makes me think of my uncle (he is 90 years old now), he was into electronics his whole life (it was also his job, did fancy improvements on acoustic scanners in the sixties), and all his projects had wooden housings. Nice to see some wood again in this forum :-)
Haha thank you very much! Indeed it also reminds me of my grandfather who I heard was a master at woodworking and built huge wooden commercial ships himself which had a big influence on me haha. I simply love the wooden housing and construction of things. Looks very old-school which I like, and easy/practical to work with. Also looks better than plastics in my opinion and gives that more ‘unique’ and ‘personalised’ feeling. That might sound like me, pretty into electronics/electrical!