Big battery bank project. Circuit related questions?
I have a project in my mind and I would love some guidance and some ideas if possible.
I already have a lot of 18650 batteries in an “acceptable” state (1800-2100mAh each) and I am planning to make a large battery bank, for use in camping mostly (smartphone charging, led bulbs, electrical air pumps 12v, etc)
I did read a lot of articles in here about battery banks, but i didn't find something as complex as my idea.
I have already made a 12v battery pack with 12x18650, 3 rows in parallel, of 4 in series in each row.
My goal was to operate a 12v air pump for inflatable mattresses. It worked like a charm! (Also created with instructions from here! Thanks for that!)
But since my “DIY disease” does not leave me in piece… I want to build a large enough pack that can support the following:
1) 12v car plug
2) 5v/1A + 5v/2.1A USB plugs
3) charge circuit for the battery pack, so I will no longer have to remove the batteries to charge them separately
4) switches in each plug
5) led voltmeter also with switch
?) at some point I would like to add a circuit to charge it with a solar charger or a mini wind turbine that i will create at some point with my 3D printer, but for now let stay with the basic stuff!
For the case i will use a modified screw organizer case, with those classic 18650 black holders from ebay. (photo below)
The case will fit almost 8 to 10 holders (4x18650), so we are talking for 32 to 40 batteries...
My main concern is the circuit design.
I have done a few simple things in the past, but this is a bit more complicated and that is why I want your guidance/ideas.
How to safely connect all those things together or maybe suggest a different plan/design, cable thickness, etc...
Links gathered so far:
I am thinking about 4S in a row. Is that too much? Or should i consider 3S?
3S Li-ion Charger PCB with BMS
For charger... something like this maybe?
12.6V 5A Charger
optional... maybe i could fit sothing like that, for laptop charging?
150W DC-DC Boost Converter
for 5v 1/2.1Amp charger i m looking at this.
5A Charger Step down Module
for usb/12v plugs/voltmeter i am considering this option.
Thanks in advance for your time!