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| Don't keep fully charged Li-Ion in long term storage, they tend to bulge |
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| Miti:
--- Quote from: RoGeorge on January 14, 2023, 12:47:29 pm ---Would it be a bad idea to charge a Li-Ion very slow, for 3-5 days non-stop using CC-CV? --- End quote --- Nope, nothing wrong with that but don’t trickle charge it. Once it is fully changed, stop, let it discharge a bit. A dedicated chip would do just that. Edit: 3-5 days seems excessive for me. Take a look at Microchip MCP73831 for single cell. It can deliver up to 500mA in an SOT23 package. A good battery should not heat up while charging at below 1C so 5-10 hours should be reasonable. |
| Siwastaja:
There is no lower limit for charging current. You can even connect it permanently to a CC-CV supply, even if some manufacturers do not want to support such operation mode. Usually they are just unclear about it and people jump to conclusions. Timeouts are recommended as some kind of extra safety layer but that is very ineffective, nearly total false sense of security. |
| james_s:
--- Quote from: Miti on January 14, 2023, 12:44:51 pm ---I just found some old Varta Li-Po batteries in a pile of junk at work after an inventory cleanup. Brand new, never used but made in 2009. They all measure zero volts at the output of the protection board, the battery itself between 2.2 and 2.3V. They are small 300mAh. I fully changed one and checked its capacity down to 3V at 50mA and at 100mA. The result in both cases was around 350mAh. Not bad for a 22yo battery. I wouldn’t normally recharge a big battery that discharged this low, but at this size I don’t think there’s any risk. --- End quote --- There's some funny math going on there, I calculate 13 years old, not 22, and I'm wondering if you got the capacities backwards because you measured higher than rated capacity? That's still a good bit of time. |
| Miti:
--- Quote from: james_s on January 14, 2023, 08:42:29 pm ---There's some funny math going on there, I calculate 13 years old, not 22, and I'm wondering if you got the capacities backwards because you measured higher than rated capacity? That's still a good bit of time. --- End quote --- :palm: Yes, 13 - 14 years. I don’t know how I calculated. I use an electronic load to check the capacity, I can’t get it wrong. In general, a good brand name such as Varta, gives the minimum capacity so is not uncommon to measure higher than specs. |
| tom66:
I've got some old Canon DSLR 7.4V Li-Ions for my very old EOS 20D (it really is due an upgrade, but it was a hand-me-down from my father and it still works.) IIRC they were rated for 1,000 photos each, and they easily did that despite being 10 years old. The risk of Li-Ions dying quickly I think is overstated. If they're even reasonably well treated they can last a decade or more. |
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