Keeppower protected rechargeable lithium ion batteries in a variety of sizes, capacities and outputs. Batteries don't get better than this!
I stock lithium ion batteries and chargers to sell with my torches. Due to supply issues, at the moment I am only selling batteries with torches. If you want spares with your torch please contact me first.
Most of my torches take 18650-sized protected batteries, but I usually stock 21700, 26650, 18350 and 14500 sized cells, as well as high-drain cells for specific torches. Among the 18650 cells, the 2,600mAh give the best bang for your buck, but I also stock high-capacity 3,400mAh cells for longer run-times.
Note that two sets of 2,600mAh batteries will give more run-time than one set of 3,400mAh and you'll be able to charge one set while using the other. It also means that, if you forget to charge the batteries in the torch, you can have a fully-charged set to fall back on.
With proper handling you should get 3-5 years of use from any of these cells. High-capacity cells won't make your torch any brighter, but high-drain cells (not the same as "high-capacity") can improve performance in some torches. Some of the most powerful torches will only work with high-drain cells.
High-drain batteries are available in both protected and unprotected formats. I sell the latest generation of high-drain, high-capacity protected batteries – which I call Super Li-Ions – namely Keeppower's R-series 3,120mAh with Sony's VTC6 cell and their 3,000mAh with Samsung's 30Q, both of which can support sustained currents of 15 amps or more.
I provide a 12-month warranty on all protected batteries, but not on unprotected cells because they can be damaged if they are misused.
Please note that there's as much technology in my batteries as in my torches - don't confuse them with the cheap-and-nasty batteries you find elsewhere - the specifications on some brands definitely belong in the fiction section of the library! But don't take my word for it - check out the independent tests here to see what you're getting for your money.