segelei

New to the forum. I had a Sigelei J80 but broke the micro USB port. I would like to convert the LiPo battery to removable 18650s or smaller and transplant the chipset and 510 connector into a larger box. In theory it seems do able but how would I go about the battery conversion?

Can anyone offer a solution? I have a Segelei 100 watt box mod. Its about 2 months old. During this time I have had to replace batteries twice. I tried Mxjo batteries Efest and the vape shop guy always suggests $15 batteries. Not sure if I am doing something wrong. Any help is appreciated.