Where to source 18650s?

A project log for Bluetooth Boombox MkII

Design and build of a small, portable, Bluetooth-enabled boombox

robgRobG 08/06/2019 at 08:200 Comments

I bought a couple of used Dyson packs, only to find they were mostly junk (new ones would have been fine as they use Sony 1900mAh cells), and a new laptop battery with a claimed 5400mAh capacity which so far looks pretty good. Will report back with measured capacity.

7/8: How disappointing: measured at only 3400mAh. Think I'll try another charge/discharge cycle and see if it improves. But at least the pack works and stays nice and cool even during quite fast charging (0.8xC). The MPPT module, on the other hand, got pretty hot even in free air. Once it's in an enclosure it'll be verging on too hot. I might change the max. charge rate from 2.8A down to 2A if I can.

9/8: After a second charge-discharge cycle the pack managed 3800mAh. Probably good enough for my needs, but I'll steer clear of Lenoge batteries in future!

25/8: Ha ha ha! The "3800mAh" pack I bought from China finally turned up today, 3 weeks late and long after I'd had the money refunded. Marked on the packet as a "$3 phone case", that's about all it's good for. I measured the capacity at a measly 860mAh. What a joke!