First off, I hope I am in the right place to ask this question, I don't really know where to go for help for this.To start, I am trying to make a portable battery to charge USB devices. So a 5 volt output. I am trying to do it cheaply, under 20 bucks. I have a bunch of laptop batteries laying around and no laptops to use them in. The one I am looking at using is a toshiba PA3383U-1BRS, It is a 14.8v 6450mAh battery. the cells inside are 12 of these -- SF US18650GR. I want to know how or if I can re arrange the cells to get the most battery life out of it. I dont know how it would be charged, what protection/charging circuts would be needed or anything like that. I know next to nothing about how this all works but my common sense says that it would be better to get the output of the pack as close to 5v as possible before doing anything with voltage regulators, to keep it efficient. Let me know what I have to do/ what I cant do/ why I am wrong/ if you need more info etc. thanks a ton guys!
To make 5 volts battery pack,take 4 piece small cells out from Toshiba 14.4V battery pack. You need to know which cell is still good. Put 4 cells in series shall do.
The biggest problem is charging. Charging a Li battery is a complicated process, with several steps that require knowledge of the chemistry, the voltage, the temperature. You really need a charger designed for that specific battery. If you rearrange the cells, then the charger won't work correctly anymore. .
