Powering Nano with 4x AA Battery Pack

[dodgyteasalesman]

Hi All,

I have been successful in powering a Nano and a WaveShare Sim7000e NB-IOT Hat with a 4x AA battery bank that has a USB port. I run a micro USB cable from the power bank to the SIM7000e hat.

The current configuration works. My project functions correctly. However, I am a little concerned about damaging my SIM7000e hat long term.

ATM, I have 2x 1.5v AA AND 2x 1.2v AA batteries in the battery bank.

This gives an output of around 5.5V which I feel may be too much for the SIM7000e hat as I've read USB ports need 5V and any more is dangerous.

When I use 3x 1.2V AND 1x 1.5V AA batteries, I get an output of 4.8-4.9V and the SIM7000E hat DOES NOT work. It cannot get a network connection. I know the voltages dont add up to the 5.1V it should be. But thats what I am reading from my multimeter. (All batteries are quite new).

My main question is: is it be safe to run 5.5V directly to the micro USB on the SIM7000E? Especially considering 4.8-4.9V does not work?

I can see on the schematic for the SIM7000E hat (which I will link), that there are a couple of capacitors connected to the 5V pin of the usb port. Im guessing these are there to smooth out the voltage and not to protect from over-voltage?

SIM7000E-NB-IoT-HAT-Schematic.pdf (106.6 KB)

Im thinking I may need to just use 4x 1.5V AA batteries and use a 5V voltage regulator connected to the power bank somehow?

Also I am guessing that mixing 1.2V and 1.5V AA batteries is bad.

Another solution would also be to grab a 5V Li-Po with atleast 2000mAH connect that to a usb port and run a cable from that port to the SIM7000E module.

Dont know what solution would be best.

Thanks for any input.

[TomGeorge]

@dodgyteasalesman

ATM, I have 2x 1.5v AA AND 2x 1.2v AA batteries in the battery bank.

What are your batteries?
If you are connecting them all in series it is not recommended.
1.5V and 1.2V indicates two different battery types/chemistry, in series you will possible flatten one type out before the other.

Can you please post a diagram of how you are powering your project?

Thanks.. Tom..

[dodgyteasalesman]

2x Nickel Metal Hydride 1.2V batteries and 2x Alkaline 1.5V batteries

Ill give a pic of the powerbank, I am guessing the batteries are indeed in series. No voltage regulation btw.

powerbank:

[mrburnette]

DC to DC converter board - Search (bing.com)

[dodgyteasalesman]

What I am thinking now...

3.7V 2000mAH lipo battery.

connected to this, a 5V, 1A Step-Up/Step-Down Voltage Regulator (efficiently produces 5 V from input voltages between 2.8 V and 22 V. )

VOUT pin connected to the 5V pin of the SIM7000e and also the 5V pin of the Arduino Nano.

Or i could use the AA batteries but I feel like the LIPO would be more compact

[paulpaulson]

Hello dodgyteasalesman

Keep it simple and stupid.

Just take a spreadsheet and create an energy balance sheet.

Everything else is like reading from a crystal ball.

[srnet]

Use a solution that uses one battery type, its far less confusing and more predicatable.

Do apreciate that AA Alkalines are around 1.55v when new and will be down to around 1.2v when half way through their life.

[dodgyteasalesman]

Yeah i am going to use a 5v converter board like mrburnette suggested with 4 of the 1.2V AA Nickel Metal Hyrdride batteries. Ill try and remember to report back if it works.