DROKUSB Buck Converter, 4pcs DC-DC Step Down Module, 6-32V to 5V, QC 3.0 Charging, Power Supply Voltage Regulator, Black

I removed the USB connector as I wanted to direct-wire a USB cable to the board. I would be nice to have a solder-pad output option rather than only the USB port.

Almost 1 & 1/2 years ago, I ordered a 10 pack of 3.2v, 50ah, Prismatic Lifepo4 cells from an online vendor. With 8 of those cells I built a 100 amp hour LiFEPO4 battery. But I had 2, 3.2v, 50ah cells remaining that I did not know what to do with.I started wondering if there was a USB module that would accept an input of a minimum of 6 volts to which I could connect the battery to charge and power USB devices. Then I discovered the DROK USB DC-DC Step Down Buck Converter capable of taking 6 volts minimum and converting it to a 5V QC 3.0 Charging Module. I read the reviews, good and bad...bad to see what people were complaining about, and decided to buy a set of 4.I figured that the converter module should work as a USB charging device when connected to the 2 remaining LiFEPO4 cells if the cells are wired in series to produce the required 6+ volts. (See the first picture of the 2 LiFEPO4 cells connected in series with one of the 2 connections coming from the converter module connected.)The second photo shows both wires connected, and the blue illuminated LED on the converter module. You can see "78% 10 m until full" on the screen of my phone. The third photo shows the charging symbol on the screen. It shows 79%. Sorry for the fuzziness of that picture.I used a few of the converter modules to charge my phone and tablet for quite a while over the last few days. I wanted to see how warm they would get. The converter module does get warm, but not too hot to handle...unlike another similar product that got far too hot to be safe. And that was only at about 1 amp of current output. I'll be submitting a brutally honest review on that one soon.I foresee finding an appropriate container in which I will cut holes for the 4 converter modules and the the 50 amp hour battery and use the power source for a portable mega-USB charging station. I'll upload pictures when I get around to making it.I am very happy that my idea panned out!

Product looks as sold. Each unit has performed well. Recommend!

Fonctionne tel qu'espéré.

I grabbed these to work with a portable tablet sized case solar panel I put together for strictly USB charging. The working connector is one of these USB converter boards.Seems to work well and YES if you have a QC3 device (I only seem to have one unfortunately) the charging voltage is increased. My QC3 Power bank charges at over 8 volts with a custom 11 volt (open) panel I made.I can't speak to what type of actual (not reported) Amp limit there really is, as I've only recorded around 8-10 watts going into a device from this small portable panel.One thing I would advise strongly: If you are going to be pushing this up to 8-10+ watts, you really should invest in a box of small heatsinks and thermal glue. I attached a photo of one of my controllers I took apart to install this heatsink on the Mosfet. These things get Really Hot when you are pushing them up there. I mean, so Hot you wouldn't be able to keep your finger on the chip! That could cause early or even immediate FAILURE.I was disappointed that even using this connector which -at least- has some of it's own capacitors, the I-phone disconnect problem still exists. Basically, if you lose solar due to Very Bad temporary shading conditions the I-phone will disconnect but it will not reconnect when the conditions then improve.Every other device I've connected does reconnect though.Remember, efficiency is going to be increased if the panel puts out voltage closer to the target finished voltage. If it is Tons Higher, the board has to work Harder to drop the voltage down. That's why I use this with the panel I built with open voltage around 11 volts. >A lot of regular solar panels have open voltage closer to 21 volts.<