diymore Li-ion Battery V3 Shield 1 Holder 3V/1A 5V/2A USB Power Bank Battery Charging Module 1865O Battery Holder

I'm mostly writing this review to document the date of which I put this into operation. When I received it, I tested it when I received it and it worked that one time fine, it powered my wireless iPhone charger. I did have it in my possession for about a week before I installed it into my 3d printed part at which time it did not work. All 3v and 5v connectors on the board shows 2.2 volts. Batteries are full, and tested four different charged batteries. The connectors to the USB-C connector shows 0 volts. I'm buying another one in case it was me that damaged it electronically, but if the new one doesn't actually work, I will be returning both.

If you're looking for a reliable and versatile battery holder for your electronics projects, the diymore 18650 Battery Holder Double Li-ion V8 Battery Shield Micro USB is an excellent choice. Upon receiving the product, I was impressed with its sturdy construction and easy-to-use design. The holder is compatible with two 18650 batteries and features a micro USB port for convenient charging. The V8 battery shield also ensures that the batteries are protected from overcharging and short-circuiting. One of the standout features of the diymore 18650 Battery Holder is its versatility. It can be used with a variety of electronics projects, including the Raspberry Pi, Arduino, and other microcontrollers. The holder's compact size also makes it ideal for portable projects that require reliable and long-lasting power. In addition to its versatility, the holder also boasts excellent battery life. When fully charged, the 18650 batteries can provide hours of uninterrupted power, making it an ideal choice for projects that require consistent and reliable power. One potential downside is that the holder may not be compatible with all battery types, so be sure to check the specifications before purchasing. Additionally, the holder may not be suitable for high-current applications, as the batteries may not be able to provide enough power. Overall, I would highly recommend the diymore 18650 Battery Holder Double Li-ion V8 Battery Shield Micro USB to anyone in need of a reliable and versatile battery holder for their electronics projects. Its sturdy construction, easy-to-use design, and excellent battery life make it a top-performing and reliable choice for a variety of applications.

Here's the good: The DC/DC converters are very efficient, both the 5V and 3.3V - like 94-95% across the whole range of input voltages that a battery is likely to generate. This is WAY better than a lot of DC/DC boost converters you can buy out there. Here's the 'meh': There are a set of LEDs on the bottom. For low current, battery powered devices, this is wasteful and consumes power for no benefit. They are easy enough to remove once you have the device operating properly. The device does not automatically turn when a battery is inserted. You must press the "enable" button once to turn it on. Here's the bad: There is an auto-sense that detects when there is no power being consumed and shuts the unit off. The definition of "no power being consumed" means less than 90mA, which is really quite a lot if you are using this device for a low-power microcontroller design. After about 30 to 35 seconds of "no-load" (<90mA) the unit will shut itself off. They provided a switch to "disable" the auto-sense, but this works by placing a fixed 90mA load on the unit to insure that there is always load above the shutoff threshold. For a long-lived battery device this is unacceptable as 90mA is more than my target design consumes and would drain the battery very quickly. This is a very poor, inefficient solution to the problem and not very good engineering. There is a solution to this, but it is a little hacky and requires cooperation with your target device. I added an external circuit (a single 2N7000 and a control line) to emulate a button press on the "enable" button every 20 seconds or so. When my system is running, I have to make sure that this circuit gets activated (pull the enable pin on the switch low for about a tenth of a second) every 20 seconds. This appears to reset the "no-load" timer and you get another 30-35 seconds. Do this every 20 seconds or so and the unit will run indefinitely at very light loads (my specific design consumes about 2mA nominally). You can't do it too fast as two quick presses of the enable button are what signals the device to shut off. I gave the unit 4 stars because the DC/DC converters are so darned efficient. If I had not been able to do the button-press emulation trick to keep the unit running under light load it would have gotten one star. I hope this helps anyone trying to use this DIYMORE battery shield for very low power designs. It you have the knowledge and provisions to tickle it appropriately it can work well, and be very efficient. If not, then the fixed load, or auto-shutoff might make it tricky to use effectively and efficiently.

Initially i thought this product came with a battery holder for 18500 cells rather than the 18650 cells it was advertised to work with. Turns out that i was trying to use the slightly longer "protected" 18650 cells that are ~70mm rather than 65mm. The product works fine with "unprotected" 18650 cells as those are 65mm.

TLDR: Only use this as a battery backup for devices that are safe to repeatedly lose power unexpectedly. I bought this "battery shield" for my Raspberry Pi, but it's completely useless as a UPS (uninterruptible power supply) because it shuts off for over a second every time external power is lost or regained. This is a big problem for Raspberry Pis which are prone to PERMANENT DATA CORRUPTION when you unplug them without safely shutting down first. Using this product would make the problem I was trying to solve twice as bad because now not only does the Raspberry Pi unexpectedly lose power when external power is lost, but also when the external power returns, since both events cause the "battery shield" to shut off its output for over a second as it switches between external and battery power.

Wanted a battery charger with multiple offshoots of 5v and 3v p&g for Arduino projects. This one charges and uses two 18650 cells. Well built, would buy more

Works excellent, only 2 things I did not like. It needs pass through charging, and remove the on off switch.if it had pass through charging it would be almost perfect.

I placed in an 18650 battery and it shorted and caught fire.