10x 18650 20000mAh 8.4V 7.2V Rechargeable Replacement Bike Light Battery Power Pack for Mountain Bicycle Bike Light Lamp Charger + US Adapter Plug

Better bigger batteries. Last longer, higher quality too. Can handle max brightness much longer than smaller batteries.

I bought a 30,000 mAH rated pack.When I tested it measuring both the intake charge and the discharge, I got only about 9000 mAH which is less than 1/3 the stated capacity.Now possibly, they are deceptively advertising double the actual capacity since the output is 8.4 v (2 banks in series) -- even so, that would translate to 18,000 mAH -- which I guess is close though short of the 20,000 mAH battery.But even assuming deceptive advertising and falling short of 20,000, it is still nowhere near by any sense the 30,000 mAH claimed.So basically, it seems like:1. The 30,000 mAH battery is the same as the 20,000 mAH battery -- you just pay more for it2. The 20,000 mAH battery is really a 10,000 mAH battery at the output 8.4v (though would be 20,000 if you took apart and rewired all the cells in parallel)3. The 10,000 mAH @8.4 v is really just 9,000So, TLDR, the 30,000 mAH battery is really only 9000 mAH @8.4v

I like the battery itself, and it seems well made, BUT: The battery holder pouch is VERY poorly made. BOTH straps pulled right out the very first time I tried to mount it to my frame. The stitches were of very weak thread, not bar-tacked as they SHOULD have been, and the webbing straps’ ends were not melted so they just stripped out. I had to melt the ends, re-stitch the mounting points and test it myself. TERRIBLE cheap construction!