12V and 5v(USB) battery pack build. help.

[Pexy]

Greetings!
My brother asked me if I could build him a battery pack with 18650 cells that he got from work.
He wants a 12V output and a 5V usb output. There are 8 cells in total.
I was thinking of doing something in these lines:
1) Connect 2 batteries in parallel and then 4 pairs in series.
2) Get a 4S BMS for charging.
-something like this: https://www.ebay.com/itm/3-4S-BMS-P...7QbTzAPwEeS2zlA6ZarHvIYWIaxgtcFvGB5SzJxzp1l4c
or this: https://www.ebay.com/itm/3S-4S-5S-3...818b:m:mU0FwbeSu6Qs1LoApTvfXxA&frcectupt=true
3) Use a 12V and a 5V regulators on the output of the BMS to have a regulated 12V and 5V USB outputs.
- something like this for the 5V:
https://www.ebay.com/itm/4-USB-Buck...m=333205758397&_trksid=p2047675.c100005.m1851
- something like one of these for 12V:
https://www.ebay.com/itm/XL4016-DC-...7a50:m:mKFxXwzaQeLUQA8Maz0fJpQ&frcectupt=true

Am I going in the right direction and would something like this work?
Do you have any recomendations. What would you change and why?
All suggestions are welcome.

Thanks,
Sven

 

[Harald Kapp]

Sounds reasonable.

 

[Audioguru]

The very cheap No-Name-Brand Lithium battery charger and protection board from China is listed at 40A!
Does it work? Will it cause an explosion and fire?

 

[Pexy]

The very cheap No-Name-Brand Lithium battery charger and protection board from China is listed at 40A!
Does it work? Will it cause an explosion and fire?

Yes i don't trust it to handle 40A but I do trust it to handle around 5Amax that will be some what limited by the output regulator.

 

[Audioguru]

A protection board is supposed to protect against high load current. This one doesn't.
What about the extremely high charging current? A mother disaster.
Why doesn't ebay say the manufacturer's name?
A car is also dangerous. Would you buy a cheap Chinese no-name-brand car??

 

[Pexy]

Ok can you then recomend me a different board?
As for the charging I was thinking of using adjustable balanced rc toys battery charger (IMAX clone).

 

[Audioguru]

I buy Name-Brand American Li-PO battery chargers from my local hobby shop. They are made for radio-controlled models and do not cost too much.

 

[hevans1944]

Would you buy a cheap Chinese no-name-brand car??

Gee, are those available now here in the USA? Can I get one with an autopilot so I can snooze while it moovze? I would rather have a Kia Turbo Sport, but mebbe Chinee be all better, huh?