0.5V-5V to 5V DC converter + AA batteries

Thread Starter

Joep_1511652376

Joined Nov 25, 2017
2
Hello,
I am a beginner(!) in electronics and almost all of my electronics knowledge comes from the internet, so I am sorry if I am asking anything obvious.
I recently purchased one of these: aliexpress.com/item/1Pcs-Mini-DC-DC-USB-0-9V-5V-to-5V-Boost-Step-up-Power-Supply-Module/32383087922.html?spm=a2g0s.9042311.0.0.ACrgGt with the idea in mind that with this thing, I would be able to charge my phone with a couple (2-4) 1.5V AA batteries.

When had received the package, I made the following setup:



The usb voltage and current meter showed 4.6 Volts.

When I connected my USB LED, it worked just fine and the current draw was around 0.11 A.
After that I connected my phone. The device read 0.11 A.
I figured that maybe the batteries weren't able to provide the power necessary for the phone to be charged.

I connected another pair of the same batteries in series, and added them in parralel to the circuit. (that would make the possible current flowing into the voltage converter higher, right?) If I connected them in series, the voltage would become higher than 5 Volts and I don't think the voltage converter likes that.

The USB LED was still drawing 0.11 A.

My phone still didn't charge and the current I read off of the display was still 0.1 A.

Does anybody maybe know why my phone isn't being charged?

My guess: the power going into the converter is still too low, and my phone detects the low current coming through the charging port and stops any current from flowing. I could be totally wrong.

I barely know anything about electronics compared to most of the people on this forum so I am sorry if I offended anyone by writing here.

Greetings, Joep.
 

bushrat

Joined Nov 29, 2014
209
Imagine putting a lawnmower engine in F-250 truck, and expecting it to move forward.. the small engine could propel a go-kart, but not something heavier.

Phones can pull as much as 2A of power to charge the batteries. if it detects current below certain threshold, it will not charge at all, simply go into stand-by mode. There isn't much power coming form 2 AA batteries (about 3.4V total), and when boosting it to 5V, it looses big chunk of current.

Description of device says it can deliver 500-600 mA of power from 2 AA batteries, highly doubt that, but if it does, then only for few minutes before the batteries are drained. AA batteries are designed to be drained at about 50 mA average, expecting to draw 800-900 mA (before voltage boost) will prematurely kill your batteries.

In other words, you can power something small from that device, but do not expect to charge a phone.
 
Last edited:

Thread Starter

Joep_1511652376

Joined Nov 25, 2017
2
Imagine putting a lawnmower engine in F-250 truck, and expecting it to move forward.. the small engine could propel a go-kart, but not something heavier.

Phones can pull as much as 2A of power to charge the batteries. if it detects current below certain threshold, it will not charge at all, simply go into stand-by mode. There isn't much power coming form 2 AA batteries (about 3.4V total), and when boosting it to 5V, it looses big chunk of current.

In other words, you can power something small from that device, but do not expect to charge a phone.
Thanks so much for your reply!

Would it theoretically work if I connected more in parralel? Or would it be more realistic if I connected more in series while using a voltage converter with a wider range?
 

crutschow

Joined Mar 14, 2008
34,285
If you want to use non-rechargeable batteries to charge your cellphone then use some with more capacity, such as alkaline D-cells which have about 8 times the energy and current capacity of AA cells.
 

Audioguru

Joined Dec 20, 2007
11,248
The Japanese AA batteries shown in the photo are labelled "For low power products" and cannot be used for this high power project. If the output of the voltage converter is 1.5A at 5V then the input at 2.5V will be at least 3.4A which is impossible from AA batteries.
 
Top