I like to give a single cell USB charger to folks who sometimes need a charge for their phones away from home. I buy the case and install a battery. I have been using unprotected Panasonic NCR 18650B 3350 mAh batteries from IMR. I am about to buy some more, and wonder what is among the best to use and at minimum cost.
Thanks, Agro, I ordered some.
aI noticed that the description of the box is “USB Power Bank Case Kit 18650 Battery Charger DIY Box. It states a capacity of 2650mAh. Does that preclude batteries with more capacity, ie 3500 mAh?
Jerry
I was mostly concerned that they would overcharge the batteries but I haven’t seen any instances of that happening with power banks, so it’s probably a moot point.
We used to think why would anyone get one, then got one, now have half a dozen of different types. Its easier to own several and leave some on the charger so you always have a full power bank to grab and use.
Make sure to optimize the cell connections as much as possible. If you can't spot weld or low temp solder the cell(s), at the very least I would suggest using neodymium magnet stuck (if nothing better) copper discs (to maximize contact surface) fixed with some sort of glue as cell contacts. This should be enough for the low drain requirements of a power bank board.
I've built some power banks in the past with certain inexpensive but good DIY circuit boards, may someone suggest something a bit beyond the basics? I mean, an efficient board with extra features beyond the usual 5+V 2A output. I prefer boards which output well above 5V or with configurable voltage output, Quick Charge and the like is nice also. Oh! Any board with selectable maximum battery voltage?
Don’t count on it having anything. For cheap and quick I bought an Xtar single cell charger, for better I bought an Engineer 500, Letokala something like that.
Two my cheap chargers had cold solder joints that failed where the shiny long contact wire connected to the circuit board. Easy to fix except case did not survive opening.
Good cells aren’t in the same level of cheap as cheap DIY powerbanks. I dipped my toe in the cheapos, but after buying a few high quality cells I’m done and sticking to premium banks. The cheap ones are false economy.
To Danglerb and everyone who believes you can't have it cheap: you can. It just is what you believe in your mind, which ends up creating the reality you experience. Let me show you an example:
The above board has been purchased by me many times, and may be found a few cents cheaper in AliExpress. Outputs up to 2A or thereabouts and charges its internal battery at 2A, tested. Used the board in custom cased powerbanks, with cells low temp soldered. Reliable. It can be found with case:
When I dropped the cheap $2 DIY banks I skipped the middle ground and went straight to name brand $10 non DIY (no soldering, just add cells), thanks for the suggestion though it looks pretty good.