3.7v to 4.5v how ?

i have an wireless game controller which runs on 3xAAA(4.5v) battery... i also have plenty of spare li-ion 3.7v batteries upto 1000mAh.. so what i'd like to do is install that rechargable li-ion battery into my game controller... so i dont hv to buy AAA batteries every time...pls guide me how...
and pls tell me as simple as possible... because i live in india..n small electronic parts like resistors,regulators etc. are reallyyyyyyyy hard to find here...
thank you in advance...

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There exists a gizmo called a "emergency charger", or words similar to this, which takes as its input, the voltage supplied by 2 AA batteries, nominally 3.0 V, and converts this to a regulated 5.0V. This gizmo is intended for powering a mobile phone, in the "emergency" scenario in which the phone's main battery is dead.

This Google image search shows what these things look like:


Anyway, I am guessing, if you could find one of these, this device could be powered by your 3.7 volt Li-ion battery, in place of the 2 AA cells, and also the 5.0 regulated output would be close enough for to power your toy that normally runs on 4.5 V from 3 AAA cells.

Also, the 5.0 V regulated output of the "emergency charger" is often supplied via a female USB port, and
that's probably the shape you want, since that would be something easy to find a plug for, if desired.

D3zire (author)  Jack A Lopez3 years ago

like this ryt ???


I don't know what "ryt" stands for.

The converter you are linking to is a step-down converter. It requires an input voltage at least 1.5 volts higher than its output voltage, so it would not work for converting 3.7V to 4.5 volts.

I meant something like this:


This is a boost converter that takes 2 AA batteries, approximately 3.0V, as input, and supplies 5.0 volts as output.

By the way, I am sort of naively assuming that your game controller will work with 5.0 V, like from a USB port, rather than 4.5 from 3xAA. But it might be good idea to test that first.

If you have a spare USB cord you can cut apart, then this would provide a way to test if your game controller can run comfortably on 5.0 V. I am guessing you have a access to a computer with a spare USB port.

Again, having your game controller tethered to a big hulking PC, or even a laptop, is not a permanent solution. This is just to test if your game controller likes running from 5.0V.

The way you tell if it does work, is if everything powers up and functions as it should, but without getting too hot.

Also on the subject of USB-powered things, I noticed this


while looking in DX's catalog, which looks to be something to measure the voltage of your USB port, and also the current flowing through it, and that might be something fun to have. It looks it will just plug right into the charger I linked to above, or any full-sized USB port.

D3zire (author)  Jack A Lopez3 years ago

hmmm thanx for that... that clearfies the diffrence between step down converter and booster... but i found a 4v rechargable battery in here local market its a chinese battery but its cheap and its working so i simply used it... and ryt=right :D

D3zire (author) 3 years ago

i think i just have to buy that converter no way to do it my self...

As Steve said it might work as is so try that first.

If it doesn't work you need a voltage multiplier.

There is an IC for that exact voltages I cant remember its part number and you would probably have to buy it on line.

Or you could build a voltage multiplier.

The down side of voltage multipliers is they will shorten your battery life.

So try the 3.7 volt battery first and see if you need to increase the voltage.

D3zire (author)  Josehf Murchison3 years ago

will this work.. ?? any down sides of this device??


D3zire (author)  Josehf Murchison3 years ago

i tried with 3.7v.. but it didnt work.. power led on device blinked once only.. didnt blink again.. working ok with alkalines..

It MIGHT run on 3.7V, but I wouldn't guarantee it. Its certainly worth a try, because the alternative is to make a boost regulator, which you won't get the parts for I suspect.

D3zire (author)  steveastrouk3 years ago

n i connected direct 3.7v power led blink once nd didnt blink again.. working fine with alkaline batteries

D3zire (author)  steveastrouk3 years ago

pls tell about boost regulator.. i hv many parts that i had collected from defrent devices.. i may find those in them..

You can't do it. Well OK you can install the battery but the controller may not function right cause it can't get the voltage it needs. It's possible the controller will operate on 3.7V but at a reduced capacity. Now if you had 2 of the batteries in series and a 5V regulator that would work much better.