I have bought two 18650 Battery Shields, each with two lithium batteries.
They have both a normal/hold switch which, in hold position, continue to stay on, even when no current is needed. This is a nice feature, as I want to use these for powering Arduinos which draw very low current most of the time.
But, when I set the switch in the hold position, a component on the board, called '089', besides the switch, begins to heat up, and the whole power pack only has power during half a day, even when nothing is connected to it!
The only information I've found on the internet about this switch, is in the thread 18650 battery shield operation and modification.
No mention is made of the malfunction of this battery shield when in hold status.
What do I have to do to make this battery shield deliver power for more than half a day?
OR
Are there any other power banks to use for 5V, without any minimum current requirement, to use for Arduinos with very low current usage?
I suspect that the Hold switch just applies a load to the output so as to keep the device turned on. And that's what produces the heat and shortens battery life. You might play around with your multimeter and confirm if that's true.
Unfortunately, the two-cell versions of this product that I've seen use a single "power bank" chip to do both the charging and 5V boost conversion, and they have dropouts when you connect or disconnect external charging source. I don't think they are usable as a UPS battery backup. And apparently these power bank controller chips have the "auto-off" function built in, so there's no way to turn it off.
I have the single-cell version, which is labeled "V3", which uses separate TP4056 charger and MT3608 boost converter, and they stay on all the time. But they are several years old, and new V3 designs may have switched over to the single power bank controller chips because they are cheaper.
This sounds like a reasonable explanation, but a crazy solution.
To be sure to keep the output "on", they simply turn on a stove which consumes the whole power bank within half a day?!
Must be designed in Chana!
Are there any alternatives to power low-consuming Ardino's for a couple of days/weeks?
Well, I didn't find any correct specifications of teh shield. It looks like Toms picture, except that mine contains not anly an on/off push button but on the opposite side also a normal/hold swith.
It's that switch which is acausing the current drain when set on 'hold'.
Sam.
I'm working on different projects with Uno and Nano, all with (very) low power consumption.
The batery packages I've found, were all turning off when the power consumption is very low.
Well as I said the single cell version I have (V3) stays on all the time without hooking up a stove. But the 5V boost regulator on all these devices is going to eat up some current when the Arduino is sleeping. So one option is to use a 3.3V Arduino such as the 3.3V 8MHz Pro Mini with its power indicator LED removed. Then you can use a TP4056 charger module and a very low dropout 3.3V linear regulator, plus a battery holder, to power it at the Vcc pin. But that requires that all the other stuff in your circuit, such as sensors, have to run at 3.3V.
Edit: The V3 version shown on the link that TomGeorge posted does not look like mine. It appears they have switched that one over to a power bank chip. So I don't know if you would be able to find a V3 with the right circuit.
There is a module called the J5019 which is a TP4056 charger and an MT3608 boost converter on the same board. You would need to add the battery holder and a USB connector, but that one will stay on with no stove. But it might be easier to use a separate TP4056 module, which has the USB input, and a separate boost converter module.
First of all, I never had the opportunity to learn electronics, so my knowledge on components and circuits is limited.
Creating additional circuits is a no-no for me. I need to work with on the shelf products.
My requirement is the ability to keep an Arduino Nano alive for weeks on a place without 230V current. So I need a battery pack (off the shelf), able to deliver a coninuous current of 5V.
My DIYMORE battery shields have no indication on the type but are exactly as Tom George showed, except that mine have a normal/hold swith and a 'component called 089' or, upside down, a 68 ohm resistor It's that resistor which heats up when the switch is set to 'hold'.
When the switch is set to 'normal', the Arduino Nano (and even an Arduino Uno) stop receiving any current after 5 seconds.
I would like to give the single battery shield a try to see how long an Arduino nano will survive on one 6.8 Ah battery.
In the mean time you may all provide me other off-the-shelf solutions for my power needs.
Tell us more about your project.
A classic Nano is not a very good candidate for low power. An Uno is worse.
An 8Mhz ProMini can run directly off a LiPo battery for a very long time,
no power-hungry boost converter needed (see post#10).
Leo..
The problem with a Pro Mini is he would have to solder in the headers, then get an FTDI adapter and hook up jumpers to program it. Sounds like he doesn't want to do that. So maybe a Nano is going to be the lowest power plug and pray.
The DIY More single cell shown in TomGeorge's link is not the one you want. You wan't one that looks like this:
Of course there's no guarantee that you'll get what's shown in the picture. More and more of these are being switched over to the bad version, so it's like a box of chocolates these days.
Thank you Sherman!
I'll buy one (or more) of these shields.
Perhaps stupid question, but can I connect two of those shields in parallel to obtain a battery pack which will give me current for a longer period, or am I missing something?
Are there any alternatives for powering an Arduino for a long period? It seems strange to me that everyone else is just using their PC or a transformer to power their Arduino's!?
I'm not sure you can parallel the output of two boost converters. One would output a higher voltage than the other, so it would supply all the load current. But maybe after that one can no longer keep up the other one would take over. I've never tried it. The logical place to do the paralleling is at the battery level. But you have to be careful that both batteries are at exactly the same voltage before you connect them together, and then never disconnect them after that. I think you would need to use unprotected batteries for that.
The key to long battery life is minimizing the load current. That includes putting everything to sleep most of the time. I have an IR remote control for my TV that's a 3.3V 8MHz Pro Mini powered directly by an 18650 battery. Even though it draws 500mA when active, it sleeps almost all the time, during which it draws less than 1uA of current. So it will probably last a year between recharges, maybe more. But you would have to get comfortable with soldering and desoldering to do that. For example, the power indicator LED on most Arduinos probably draws 5mA or so. That's a complete waste. But you can remove it with a soldering iron.
Voltaic Systems makes a series of always-on power banks. The V25 is the smallest at 6400mAh for $44 at Amazon. I don't know of any other power banks with that feature, and I don't know of any multi-cell shield designs that actually work properly.
