https://www.ebay.co.uk/itm/Useful-8-4V-Waterproof-Battery-Pack-Case-House-Cover-For-Bicycle-Bike-Lamp-SY/362136679680?_trkparms=aid=111001&algo=REC.SEED&ao=1&asc=20160727114228&meid=ee29b1a50deb427bad24ac19c2b64473&pid=100290&rk=1&rkt=4&sd=362136679680&_trksid=p2060778.c100290.m3507
if you have a 8.4v wall wart then you can charge the cells in the case.
