Hello, I could not find a forum group specifically for power supply/ups/charging/battery. My question/ concern is I purchased (2) 18650 Battery Charge Shield Board V3 and when the unit's charge connector is connected to a live power source with battery installed, the unit will provide the 3.3 and 5 volts to the external boards, such as Uno; however, when I unplugged the charge cable, the battery only stays on for 5 seconds and then shuts off, bringing down the Uno that is using it. I tried both boards and 6 different batteries. Both boards do the same thing. I know the batteries are good, because I can just use a basic buck/boost converter and run the UNO for long periods of time. (instead of just 5 seconds, if that same battery is plugged into these 18650 chargers) I cannot find any adjustment POTs or things to change. Anyone have this experience and able to fix it? Here is the link of what I purchased:
Hi,
Welcome to the forum.
Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .
I have a coupe of these units and I haven't had a play yet, but I would think it has a load sensitive shut off.
That is you have to be using more than a certain amount of current to keep the unit switched ON.
Try adding a couple of LEDs with current limit resistors to the 5V of the UNO, or get the UNO to flash them and see if it stays ON.
I can't check mine at the moment, I'll look in the next day or so, but someone else may be able to confirm my thought.
Tom... 
hello Tom,
I did not think of adding more load. I was testing with 1 LED load, and it failed, but I too will test with more load next time and see what I get. Did you test your's yet? Thanks, Neil
It's a charger. That's all it does. Why would you disconnect the cable ? If the battery is charged then remove it. Don't try to use a charger as a battery power source. There is nothing wrong with it.
It is not supposed to supply power when you remove the cable because the connector is a USB-A and
the website link says it is designed for Arduino charge, which means you connect a standard USB A-B
cable to charge you battery and then you remove the battery and the cable.
If you want a battery holder with charger input, that's a different device and you'll have to look for it.
You are trying to use a pair of scissors as a pair of pliers. You got what you paid for. If you want something else, find it and order it.
I'm confused... are there two different units out there that look similar? The Wemos one looks like a charger and a supply.
I believe it is supposed to be a charger and UPS. That is why it has connections for outputs (USB, 5volts and 3.3 volts.) To supply power when the unit is unplugged from being charged. And it actually does supply power for about 5 seconds. I think it may have some overload or under load protection that I cannot adjust. Can someone hack this board and tell me what to change? Or is it truly only a charger? (why have all the outputs then?) T
It should be easy to determine if it has onboard regulators that run off the battery after the cable is removed. It is quite possible that they are directly connected so they still work during charging.
Look for the schematic a datasheet or surface mount regulator ICs.
Did you get to the bottom of this in the end? I have just purchased one and am having similar weird issues.
I have a similar / same one I purchased from Banggood. It works fine for me. It is indeed a:
18650 Battery Charger
3.7V to 5V boost converter
an over charge over drain circuit.
When I first got mine I plugged in the 18650 (be very careful about the polarity. I followed the board printing but on mine the battery holder was in backwards so the markings on the holder were reversed.
I then let it charge the battery until the Green Charged light lite.
Did you check the on off switch was ON?
John
I'm waiting for mine to arrive from Banggood. Any day now. Here's a video by Andreas Spiess on this item (I think it's the same item.)
And here's website with more information:
It clearly is a charger and UPS with three LDO regulators to 3.3V and a boost regulator to 5V. There's no mention of any low-current auto-shutoff, and I don't think any of the chips I see in pictures have that capability.
Also, it appears that when the USB source is plugged in, current flows through the charger to the battery and to the regulators. I don't see any reason why the battery wouldn't just continue to power the regulators directly when USB is unplugged and the charger shuts down. All I can think of is that something is going wrong with the protection circuit (the DW01) and it's "protecting" the battery by shutting it down. The way to test for that is to connect the battery's negative terminal directly to gound, which bypasses all the protection stuff (the protection actually works by disconnecting the negative terminal from ground). But that's a high-pucker-factor move that you would want to try only if your 18650 already has protection built in, and only for a short time. And even if that's the problem, fixing it might not be easy.
Very disappointing that you're having these problems. I have big plans for modifying mine, but it needs to work first.
when I unplugged the charge cable, the battery only stays on for 5 seconds and then shuts off
Are you SURE it is not doing EXACTLY what it was designed to do ?
A battery charger is just that.
What you need is a charging circuit that is designed to maintain the battery voltage , as opposed to
one that is only designed to charge a battery but not provide battery output when the input power is
removed.
If the batteries are actually charged when you REMOVE them from the circuit (ie measure 4.2V with a DMM):
THEN,
The charge board is working correctly and is not designed to output battery voltage without input
power.
If the batteries are NOT charged (not 4.2V) when removed, then it is NOT working correctly.
Does anyone have the dual 18650 v8 version of this?
Thanks for the comments.
Its the dual-18650 version that I have.
This battery board I have is advertised as an Arduino shield and designed to power your projects.
Therefore I naturally assumed that it had the ability to be charged from a micro-usb power brick and once charged would be able to be unplugged and power my projects.
I happened to use 2 18650 cells that I had already charged in a dedicated charger. So I assumed I could simply install them in this 'shield' and then solder wires from the 3.3v and 5v outputs to run my project.
I am building some stand-alone LED units with 2812B 8x8 boards and NodeMCU boards, each board receives a wi-fi command telling it which colour/pattern routine to run.
I need to build a unit that includes the ability to plug in a charge cable to charge it, then unplug it to use it.
I have e-mailed the supplier for confirmation as to how its supposed to work.
This morning I am running a soak test to see how long the 18650 batteries last in my project.
To get the unit to power up, I first installed the 2 charged batteries, plugged the 3.3v pin into my project and then had to plug a micro-usb charger in for 10 secs to get it to wake up. I was then able to unplug the charger and leave it running.
To be clear, I'm actually using a USB output cable from the unit, with the other end (micro-usb) powering the Arduino board. Then 5v output from solder pad to power the WS2812 panel (8x8).
Maybe the USB output port needs to be used to keep it awake?
I still don't know how you are supposed to wake it up though...
The switch on mine is momentary and just seems to show you the battery state of charge on a set of LED's underneath.
I have attached a photo of the unit I have.
@OP
see Blue407's post.
Blue407:
To get the unit to power up, I first installed the 2 charged batteries, plugged the 3.3v pin into my project and then had to plug a micro-usb charger in for 10 secs to get it to wake up. I was then able to unplug the charger and leave it running.
I can only conclude that the circuit for the dual-cell V8 is different from the single-cell V3. I'm pretty sure the positive battery terminal in the V3 is connected directly to the input of the 3.3V LDO regulators. If that's the case, there's nothing there to delay things, or require that the power be plugged in to at least get output at the 3.3V terminals. But apparently that's not the case with the V8. In any case, it's difficult to find a solution without a schematic. And to further complicate things, it appears there is now a V8.1, which appears to be completely different from V8:
https://www.aliexpress.com/item/4000704300145.html?
Despite what the silkscreen says, when I go to www.diymore.cc, I find nothing on V8.1.
In reading through some of the Amazon reviews on their V8s, I see several comments that if you have power connected and fully charged batteries, then disconnect power, the Arduino resets. It may take several seconds before battery power takes over, which of course would make it unsuitable as a UPS. Does yours do that too?
All I can suggest is that I don't think it's supposed to be working the way it's working for you, but it's possible it's working the way they designed it. I guess there's a chance V8.1 would work better, but who knows.
I was going to order a V8, but now am not sure which one to order. But in either case, it would take a month to get to me, maybe longer. My V3 is due today, but I'm not holding my breath.
Regarding battery protection.
My board has a DW01-P that protects the battery.
TomGeorge:
Hi,
I found this schematic for I believe the V3 unit.
Thanks very much for posting that. It's pretty much what I expected, and as far as I can tell, there's nothing there that would require a minimum current to be drawn to keep it going, and nothing that would prevent the battery from kicking in immediately if USB was unplugged. I was expecting the dual 18650 V8 to be essentially the same since the batteries are paralleled. But it appears that's not the case. If you find a schematic for that, I'd love to see it.
Not really relevant to issues at hand, but I'm curious why S1 and R1 are there. And I also wonder about the paralleled diodes S2 and S4. I thought you weren't supposed to do that.
So I'm a little lost here. Whatever happened to the OP's issue ?
Did that ever get resolved ?
Has this thread been hijacked or is all of this the answer to the OP's problem ?
Signed,
Confused
The OP started this thread a year ago. The recent posts started with Blue407 asking if there had ever been a resolution. We still don't know about that, but we're trying to figure out Blue's V8 issues.