Re: Here is a good used source for 18650 batteries
Well, was trying to use that laptop battery pack as is, and it refused to give me any power. So I had to open it. Got 4 purple shrink wrapped noname INR18650E and they were *DEAD* or at least they were around 2VPC. They were marked 3.7V 9.62WhPC = 2.6Ah. No shorted cells. So, playing with fire, I tried using a power supply to charge them without protection. Seem to slowly take charge... though unsure about the quality of the cells, they seem somewhat balanced.
The pack seemed to exhibit about 0.5Ω ESR by cursory estimation at this SoC, alas, 125mΩ/cell which is kind of crappy. However they are still kind of really undercharged. Will have to check again after charging 1A for 15 mins or so which would be 0.25Ah... which really isn't much energy, but would be interesting to see their behavior at 10% charge...
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At ~ 20% SoC the ESR has dropped to 85mΩ/cell. This is a bit better...
Well, was trying to use that laptop battery pack as is, and it refused to give me any power. So I had to open it. Got 4 purple shrink wrapped noname INR18650E and they were *DEAD* or at least they were around 2VPC. They were marked 3.7V 9.62WhPC = 2.6Ah. No shorted cells. So, playing with fire, I tried using a power supply to charge them without protection. Seem to slowly take charge... though unsure about the quality of the cells, they seem somewhat balanced.
The pack seemed to exhibit about 0.5Ω ESR by cursory estimation at this SoC, alas, 125mΩ/cell which is kind of crappy. However they are still kind of really undercharged. Will have to check again after charging 1A for 15 mins or so which would be 0.25Ah... which really isn't much energy, but would be interesting to see their behavior at 10% charge...
--
At ~ 20% SoC the ESR has dropped to 85mΩ/cell. This is a bit better...
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