The introduction of the Low self-discharge NiMH battery (LSD-NiMH) in 2005 made rechargeable AA and AAA sized batteries more viable for powering LED bicycle lights. Previously, the self-discharge effect of NiCAD and NiMH batteries caused the battery to run down over a period of weeks or a few months, even when not in use. This was particularly a problem for low powered LED lights, and for users who only used their bicycle lights occasionally. The LSD-NiMH battery greatly reduced the self-discharge effect, allowing the battery to keep its charge for a year or more.
For higher-powered lights, an external battery pack of 12V VRLA battery is often required. These battery packs usually strap to the top tube of the frame, or come in the shape that fits in a water bottle cage, or can be placed in a basket. A cable connects the battery pack to the light. Another advantage with battery power (especially with 12 volt) is the ability to power other components outside of lighting, as well as all from one battery (as long as they run safe on 12 volts) though wire spaghetti from splicing can be a setback depending on how complicated the electric system is.
Alternatively, Li-ion and LiPo batteries have been becoming more popular with bicyclists due to their higher capacity and lighter weight compared with conventional batteries. More specifically, the 18650 battery, which has been popular with electric car manufacturers (for the same reasons) and are commonly found in laptops and flashlights.
With the development of lithium batteries, 18650 battery have come into a much mature development level. 18650 is the very first lithium-ion battery cell, developed by Sony company in 1984, which production technology is the most mature and stable in all kinds of lithium batteries.
You can say 18650 is the ancestor of lithium batteries. And it has been put into auto-production for a standardized and scale production for years. 18650 battery has the highest level in auto-standardization production so far.
And now 18650 battery applied much wildly than before, e.g. Medical devices, car etc.
American Giant Terras, using Panasonic ternary 18650 cell, created a magic tale to navigate exceed 400miles. Which made 18650 battery announced.