In the 9 or so years I've been harvesting 18650's, admittedly, I'm still unsure what a "cheap" cell is supposed to look like... or if there even is such a thing as a cheap cell. Many of those salvaged cells I harvested were labelled to easily identify the manufacturer (and capacity & chemistry), but many have no identifiable markings at all, making it extremely risky to combine them with cells from different sources... so I don't. The unlabelled cells I reserve for flashlights and other single cell devices.
Michael Cox wrote:My understanding is that cheap cells - even if new - are more prone to failure and fires.
Quite true for many Li-ion chemistrys, but not all. FLA's and SLA's suffer from the same temperature deficiency, but at a fraction of the cost. If you seek rechargeable Li-ion cells that endure the lower temps... then sample Lithium Titanium Oxide (LTO) cells. Unfortunately, LTO's have a much low energy density, but longer life span.
Sebastian Köln wrote:Lithium-Ion batteries have poor low temperature (< 10°C) performance. Their discharge (and charge) current will be a fraction of the normal one.
Eugene Kenny wrote:If you seek rechargeable Li-ion cells that endure the lower temps... then sample Lithium Titanium Oxide (LTO) cells. Unfortunately, LTO's have a much low energy density, but longer life span.
All of my Makita lithium 1.5Ah packs are 5 cells in series = 18.4V nominal. The Makita 3Ah packs use the same 1.5Ah cells but have 10 cells arranged in 5S 2P, to achieve 18.4V but double the Ah. I've Never seen an 18V Makita pack with 8 cells???
Michael Cox wrote:... Makita brand, 8 cells, on the outside it says 6Ah which would suggest high capacity cells. When I got it open the cells inside were only rated to half that!...