Charging 3 12v packs with one solar panel

[GeorgeF]

This prefrabricated portable chicom housing for 2p3s, with built-in BMS and 12v & 5v usb ouput and input for charging, can be ordered online.

If someone wants to charge 3 of those packs with one solar panel and one stepdown @ for example 12.3v will it work?

[bob-n]

What is the input voltage and current rating for that device?

A standard 18650 lithium cell requires 4.2V at 0.52A for charging, or roughly 2.2 watts. Your pack appears to have 6 cells, so if it uses 6 standard 18650 cells, it would need roughly 18 watts for charging one pack (2.2 watts times 6 plus a bit for losses). You would need 54 watts for 3 packs.

You can easily get 54 watts from one 100 watt or larger solar panel with good sun. Assuming that the device is meant to be powered from a fixed 12V input (car battery or wall wart), you can simply wire three pack inputs in parallel.

As you say, you also need a solar panel down converter. A simple PWM converter might work, or you could get a MPPT converter for better performance over a wide range of light levels.

[GeorgeF]

Are diodes needed @ charge-inputs (3x) ?

[bob-n]

George,
Probably no need for diodes, but I can't be sure with just a photo. I need more information on that device. Do you have a brand/model? Spec sheet? Anything else?

[GeorgeF]

No brand no specs. It is just a housing with built-in bms.

Batteries you to have buy yourself.

[GeorgeF]

This is a a smaller version

[bob-n]

Do you have a description? Anything other than photos? It's tough to do anything other than guess from photos.

[GeorgeF]

Only this

[bob-n]

Yes, that is helpful. That confirms all of my theories. You can certainly charge three of those from one 100 watt panel and converter, without diodes.

[GeorgeF]

Thanks Bob-N