Author Options:

Manage a single 3.7V Li-ion cell for 5V load? Answered

This is a 3.7 V 10Ah Li-ion cell. Load requires 5V 1A.

Can you give me a general idea to have something like this -
1. Power the load from 1 single cell
2. When connected to external power source, like USB, disengage the battery and power the load from USB delivering 5V 1A, and simultaneously charge the cell but at 5A.



The forums are retiring in 2021 and are now closed for new topics and comments.

Best Answer 6 years ago

I can see this happening. A few things to take t look at.

What you need is called a Boost Converter. It will raise the voltage from 3.7 to 5v. I found one with 2A output on eBay, i'll send you a link.

To charge your batt, you will be hard pressed to find a USB solution. Most USB plugs will only let you draw 1-2 Amps; It will have to be a external power supply. I would suggest a RC hobby charger, The big ones. That is about the only way you will charge that massive( -ly Sweet ! ) battery in a reasonable time.

Last, you mentioned you wanted almost a "pass-through" charging system that will switch between the two sources. something like this, www.adafruit.com/products/1944 would be Ideal !, problem is it will only supply 500 ma. They saw you can draw higher current (the 1 Amp you need) but I would erge caution, Or buy a few of them :P Alternatively, just unplug the batt to charge it.

PM me if you need help. Hope to see what your making with that massive battery ! I'm drooling over the 50Amp discharge rate :D


6 years ago

Not as easy as you may like.

to get 5 volts from the 3.7 cll is a complex process that wouldn't suite an none electronic person. i am assuming this fits you as your asking the question.

In addition you would need to build a complex charging circuit to avoid over charging the cell. You can't get 5 A from a 1 A source.

in a phone these things are generally micro processor controlled.

Your idea is impractical. Sorry.


Answer 6 years ago