# can i use this for a DIY power bank to charge my smart phone

Hi All

is this safe for a DIY power bank to charge my smart phone with a 18650 cell ?

this chip have any one tried it ?

Don’t expect to fully charge your phone with a single 18650 though. Read this thread to get alittle better understanding.
And no it won’t work from a 18650 cell, it requires a 5 volt input to work.

I knew there was better ones.
this
one you set the output voltage yourself by the potentiometer using a multimeter
this one
Gives you an automatic voltage of 5 volts, and you can just attach and use a 18650, but i’ll refer you to my first post link about charging with a single 18650.

Lol
Lol
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Yes you can charge your phone with the linked module, just solder the battery on the correct spots.
There are also housings available for making a nice DIY power bank, for just few dollars.
I have ordered this along with this
But I have not assembled it because I want to add a flashlight…
Or buy the ENB power bank for two cells, this one is tested as a good one.
Already assembled power banks often have crappy cells in it so I wouldn’t recommend them.
How often/much you can charge your phone depends on the phonebatterycapacity and the circuit efficiency.
I have a tubular power bank with a Panasonic ncrA 3100mAh cell and I can charge my phone a bit more than 100% with it? in my phone is a 1200mAh battery, so you can see what he wanted to say: efficiency is low…

But it is still better than nothing in a small size.

Werner have you tried the one you posted yet ? and what is the difference between the one you ordered and the one i linked above ?

Any of these are called "boost" circuits..they take the 4.2-3.2vdc (nominal 3.7vdc) of a Li Ion battery and convert it up to 5vdc, which powers your phone

You have to understand that there are two conversions going on here, 1. being the conversion of battery to 5vdc, then back down from 5vdc into a battery, there are losses (considerable in some cases) in both of these conversions

A cell phone has what a 1000-2000mAh LiPo flat pack battery in it, so you would need something bigger than that to fully charge your cell phone, some say upwards of 20-40% larger capacity. Plus some of the more powerful smartphones like the iPhone need over 2 amps or 2000mAh to charge or it won't go into charge mode. I recommend the multiple 18650 battery types where you can put in 2-4x 18650's in parallel (adding the current capability while maintaining the same voltage) and that have dual outputs 1 being 2.1A and the other 1A. You also have to realize they stick the cheapest batteries in them and sell them for a premium

I say get the shell, then get VERY good Panasonic or high end batteries to have a viable "portable" power bank, otherwise you never know what you get

Just like people here have shown with the fake batteries, well, they sell "fake" stuff with very cheap batteries

His followup AFTER he put in good batteries

Fasttech’s description is pretty crappy, but it should work.

Couple of points… not all iphones need 2a charging current. My iphone 4 only needs .5a, but it also needs a resistor on one of the data lines to think that it’s connected to a proper charger. The mysteries of Apple device charging (video) « Adafruit Industries – Makers, hackers, artists, designers and engineers!

Some of the empty enclosures you’ll find on FT might require soldering to the battery contact, which isn’t necessarily easy.

If you don’t want to diy, I’ve got this one and it works fine. https://www.fasttech.com/products/1424/10004475/1342700-1a-2-18650-single-usb-output-mobile-power-pack The two major things I like is that the batteries are parallel, so I can use one or two, and it doesn’t screw closed, so is easy to swap batteries out. HKJ has reviews of other battery packs, if you’re interested.