Originally Posted by
NativePaul
18650s for minis and 26650s for full size classes are in the naviga rule book, as an alternative to LiPos. They are not LiPo they are LiFePo4 so have a lower voltage than LiPo they are also heavier for the power or the weight, but they are a much more robust cell, less suseptable to overdisharging, with a high cycle life, and the chemistry doesnt like burning as much. There are now rectangular LiPo like packs LiFePo4 packs that are robuster than LiPos without the weight and form factor penalty of the metal case.
The originals are A123 cells the 26650s had a very high power density at the time and 3s2p 26650, was roughly equivalent to the 2s 5000mAh we got with 280g 6 or 7 yerars ago, a little more power, but with a chunk more weight, they were pretty popular, the 3s 1100mAh 18650, was never really competitive with 110g of LiPo for minis which was 2s 1800mAh at the time,but things have moved on a lot for LiPos and they have been outclassed, now for the same 280g we have 50% more energy, I haven't seen an 18650 or 26650 pack being used for many years. Although they hasve been cloned a lot since I last used them, most offer higher energy density but less power density, for torches and laptops etc, I havent heard of any with more power density than A123s, which are a genuine constant 30A for 18650 and 50A for 26650. The best way to buy 26650s was as a twin pack of dewalt 32v(Europe) or 36v(USA) batteries, which contain 10 A123 cells each, for the same price as 10 loose cells from A123. The typical 2000+mAh 18650 is only good for about 5A continous before the voltage drops to the same level.
I still have mine, and they will never go back in a boat. I really must get around to stripping them out of their 3s packs and making a 4s5p lightweight car battery from them.