I am trying to make a portable 12 V Dc power supply using rechargeable batteries for my project, but I do not know from where to start, I have already read blogs and watched tutorials on youTube, but most of the there dealing with 3.7 Lipo batteries, can anyone please help and guide me. I will be vert grateful of you.
Thank You So Much
A "portable 12 DC supply" using rechargeable batteries has already been invented.
I think you need to provide more information
Actually Sir I want a system that can charge and protect the 12 V battery bank ( made up of 3.7 lipo batteries). Hope you got my point. Actually I am thinking to make such kind a light weight battery bank but I do not know how to start.
Thank You sir for your reply.
You want a 3S cell balance charger circuit.
Pick ones with features you think are important and look up online and see if there are any half-decent modules. Or make your own.
Discharge is easy. Just wire them up in series (if they are not already) and connect load to them. You can throw in a PPTC or some other "stuff" for protection.
I don't trust those with bi-directional power leads.
If you don't mind being finicky, you can get a 1S charger and charge 3 one at a time from, say, a USB outlet.
Firstly you need to be careful when using lipo batteries as they can catch fire/explode if not handled correctly (see youtube for lots of examples). You will need a balance charger which is able to monitor the voltage of each cell.
They also need to be protected from over current draw and over discharge and ideally have their temperature monitored.
It depends what sort of current draw you require and how accurate you need the 12v to be.
Each cell when fully charged will be around 4.2v but this will drop to around 3v when discharged. So 3 in series when charged will be around 12.6v
You can get cheap circuit boards on eBay to handle the charging and protection boards to handle preventing over discharge.
You can also get cheap buck/boost boards which will give you an accurate 12v but the price increases as your current requirement increases.
I am using a pack like this as a portable power source. It's intended as backup battery pack for security camera's. It has the Lipo charging/protection circuit built-in.
I am working on providing power to some portable underwater equipment, so far I have a block diagram:
I have loads of other things to do, so it will be a while before I get around to producing hardware.
Hi,
I didn't build this circuit but it seems to meet your need.
But you can search the WEB with the argument:
"Step Up 3.7V 12V"
Can we clarify this? DO you want a PORTABLE (ie stand-alone) 12V supply? ie a 12l SLAB as above?
OR a mains operated supply to CHARGE the batteries, like this:
and a charging system to protect the cells, like this
Nice diagrams 
LOL
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