12Pcs 5V Boost Step Up Step-up Transformers Power Supply Module Lithium Battery Charge Protection Board for DIY Charger,with LED Display,USB and Micro Port

First off this review is on the Onyehn 5Pcs 5V Boost Step Up Power Supply Module only. The main difference from description of the product, is the CHIP onboard, it is not a 134N3P, but is a HOTCHIP HT4928S instead. And there is no blue LED on board so don't haunt for it. The RED LED is labled LED 2 on board, with Led1, Led 3, and Led 4 positions vacant on board. Pin 2 of HT4928S connects to Led 2, and flashes for charging, and steady on for finish charge. Pin 1 of HT4928S does connect to vacant + Led 1, but goes HIGH when Pin 2 going to Led 2, is off. This would have been handy to tell when output V is on, but is sadly MIA. I include the schematic, plus front, back photos for reference. I am unable to find English description of internal setup of chip, maybe someone else will. The HOTCHIP does charge better than any of the TP4056 ones I have, and shuts off at 4.26v full charge. The chip runs warmer than others, and even the regular size USB socket is used as heatsink. At power off on supply, the VOUT on both USB sockets goes to 5.19V for about two seconds then off, if you don't have load. Under 1 A load with charge power cut off, the boost holds 5.1V. At 2A the voltage shuts off. Have not tested the low V on Battery shut off point. This is a great ultra small device that does work.

Simple boards that I have used for a few different projects, mostly connecting a single 18650 lithium cell to for powering various lighting and Arduino boards. None were DOA and they were pretty easy to snap apart. I did accidently connect one using a battery box that was outputting 7-8 volts and not the 3-5 they are designed for. I thought I had a bad board because it kept shutting off. I realized my mistake, replaced the power source to a single 18650 cell and the board worked great again. Been running several of them for 8-10 hours a day for a few weeks now and no issues on overheating or dying. Will defiantly be getting these again.

Yup! it does work as boost 3.7vDC to 5vDC DC-DC converter as well as charge 3.7v Li-Ion batteries at about 700mAh under ideal conditions. The battery low voltage cutoff seems to be at 3.2vDC before it quits boosting 5vDC output. The only caveat is that the load must draw 60mAh minimum at all times for the boost converter to keep working. This could be a problem for low current draw applications. This is one major limitation of this design. The conversion rate seems 85% efficiency under real load conditions. It outputs 5.1vDC at 700-800mAh max any more load and it shuts itself off. There is only one RED LED on-board. Blue LED is not present, that RED shows ON state (Solid) and Blinks when charging and when charging is complete it becomes solid RED As other reviewers have pointed out it is "HOTCHIP HT4928S" based. Funny that they named the chip like that since it does get very hot during operation especially during charging 18650 3.7v Li-Ion batteries and high load conditions during the DC-DC conversion process. The USB port's metal fins are used as heatsink to some extent. This is a tiny self contained device suitable for various projects while it is not perfect it still works. For the price you pay you cannot complain much Rating the product with four stars!

I like the cutoff voltage being 3V, many of these types of boards will not cutoff until down to 2.5V, which I do not like to ever let my batteries drain that low (bad for longevity) so these positively stand out to me in that way

I put together a power bank with this and a 5.3 amp hour cell and plugged it in to charge on a 1 amp charger. It took over nine hours to reach a full charge and the board was very hot the whole time, discharging works too as I am charging my phone but the section of the power bank with this circuit in it is very hot, the usb plugged into it is almost too hot to touch. These boards are horribly inefficient so I recommend nearly anything but this style of power bank board.

They work well, they seem to have a decent output power as they will charge my phone at full speed.

How in the name of ALL that is holy, can you sell an item and tell the buyer that you might get the old product, or you might get the new product which is DRAMATICALLY different in actual operation. Help me understand how this was a good marketing decision? The original product had LED's that ACTUALLY told you what was going on during charging. The NEW product has none of this, you will have NO IDEA when the battery you are charging is actually DONE, you will have no idea about anything because some genius decided those pesky LED's where maybe too expensive? Or too difficult for a MACHINE to put on the board? Are you kidding me? I got these because a really cool project for my 3d printer suggested this exact part, except the part referenced IS NOT what you will/or will not actually get. They sort of leave that as a bit of mystery. Was it too hard to sell the old part, delete the listing and THEN list your crappy replacement part and potentially get LOTS of angry reviews because its a piece of junk? What were they thinking! Not an Amazon problem, but Definitely A SUPPLIER issue.

This seems to be the smallest Lithium charger available. And it even has the bonus 5v usb boost converter too. It charges a 2000 mah battery in about four hours. Wonderful little devices.