DIY Power bank for less than 5$

[wintech]

https://youtu.be/WeayJ7kyYSU

[aandrew]

• Questionable batteries - check.
• soldering to batteries (and fuses) - check.
  
• flammable enclosure - check.
  

A great example of how *not* to build a $5 battery bank, although I do admit that using the fuses and series resistors will probably keep you safe, especially since the battery bank module doesn't look like it can supply any kind of serious current.

Any reason why you chose to solder rather than just using 18650 battery holders such as https://www.aliexpress.com/item/32821725795.html (cheaper/alternate options also exist)?

[ledtester]

Some things I don't understand about the schematic:



1. Why is the fuse protecting only one of the batteries in each pair? Seems that putting it in series with the 10R makes more sense.

2. Won't there be a huge voltage drop over the 10R resistors? If you want 5V 1A at the output, then you need at least 1.6W from each pair of cells. If a cell pair is charged up to 4V that means a pair needs to deliver 400mA. The drop across the 10R will be 4V! Or am I missing something?

[wintech]

@ledtester
Well I've messed up the diagram.The 3 resistors should connect to the + terminal like that:Battery pack 1 to battery pack 2 ,battery pack 3 to battery pack 2 and battery pack 1 to battery pack 3.

[Monkeh]

So for your less than $5 you've got an ugly, flimsy, bulky package with highly questionable capacity, which can source 1A on a really good day?

I'll stick to proper ones.

[StillTrying]

I'm afraid that's one of the worst 'electrical things' I've ever seen.