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Nice comment! Just a things I'd figure I'd add, cause I know a bit about batteries and this is HN after all: - LiPo cells are really LiIon cells, the name is misleading. There exist true LiPo cells but unless you're a battery researcher you probably don't have one. - 18650 batteries _are_ LiIon batteries (just as LiPo batteries are) they're just a specific form factor: a 65mm long cylinder with diameter 18mm. (Technically, 18650 is just a form factor, so you can have a non-LiIon 18650 - and I have two non LiIon 18650 cells - but it's exceedingly rare for an 18650 to be non-LiIon and I don't believe you can buy them.) - Pretty much all batteries are only made in extremely large amounts and sold to large companies for either industrial, automotive, or consumer electronic uses. 18650s are made for industrial and automotive uses. RC, e-bikes, vape pens, etc are just a blip on the radar compared to the enormous battery consumption by industrial, automotive, or consumer electronic uses. This means that none of the battery companies make cells for these uses. This means that the companies that make battery packs for RC uses or e-bikes are making packs out of leftover cells from larger companies. If you buy, for example, a pack online for your quadcopter, it is probably made by a factory that takes 10 cell-phone, or laptop, or power drill cells and puts them together. - Because there are space/weight losses associated with getting the reaction to happen in a cellphone battery sized space, and there are losses from packing ten cellphone packs together, "LiPo" packs are generally a bad idea. - However, 18650 cells are relatively space/weight efficient to begin with, and there are a bunch of large companies pouring many billions of dollars into improving their 18650 format battery processes, so they're by far the best thing to use when you're concerned about weight/power/capacity. - Lead acid packs are, like you said, a horrible idea, unless you have strange constraints. If you need the ability to treat them horribly, or need high power, get lithium ferrophosphate cells. If you need to treat them horribly, need high power, AND need extremely low cost, then lead-acid cells may be your best bet. - Building your own battery packs will save you an enormous amount of money. If you don't like working with electricity, hiring someone else to build your packs will save you a bit less money, but it's definitely worth it. When you build your own packs, you know what you're getting, as the vast majority of these pack websites overcharge you for fake cells. I build very large packs occasionally. If anyone's curious on how to build their own, or wants sources to find good cells cheap, my email's in my profile. |