3 Sets Kits 3.7V Li-ion 18650 Lithium Lipo Battery Charging Board 5V USB Step UP Module

They all worked and I was able to make a portable battery charger that was able to double as an anything 5v off of USB port travel charger. I even added a solar panel to charge the internal battery outside! Everything works great!

Charging board works to charge the battery pack, but the output power board does not deliver enough current to fast charge devices. Very inefficient and as another reviewer noted it does drain the pack quite fast. I have 4 18650 batteries hooked up and it will not fully charge a Samsung Galaxy S9. Brand name charging packs of similar capacity will charge my phone twice.

Easy to set up, but has limited potential and drains your batteries fast

Did everything I expected of it...

The USB boards do not provide enough power to charge any Apple device. Boooo

Good item

Product operates properly