18650 Cells: Difference between revisions
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:*Cycle life and specs - [https://cdn.shopify.com/s/files/1/0674/3651/files/samsung-18650-30Q-spec-sheet.pdf?13304021761413850609] - 250 cycles to 70% of rated | :*Cycle life and specs - [https://cdn.shopify.com/s/files/1/0674/3651/files/samsung-18650-30Q-spec-sheet.pdf?13304021761413850609] - 250 cycles to 70% of rated | ||
:*1000 cycles at 6A discharge rate bottoming at about 60% capacity for 2000 cycles? - [https://www.fasttech.com/forums/1686801/t/1238167/what-is-their-cycle-life/1]. So these last pretty long. | :*1000 cycles at 6A discharge rate bottoming at about 60% capacity for 2000 cycles? - [https://www.fasttech.com/forums/1686801/t/1238167/what-is-their-cycle-life/1]. So these last pretty long. | ||
*From lifetime design perspective, 2000 cycles is only 3 years, though. If used daily - batteries last only 3 years. | |||
=Links= | =Links= | ||
Revision as of 12:52, 22 December 2019
What it it?
General Performance
- 10A discharge, self-protection circuit inside.
- 3.7V
- 3 Ahr
- 18 minutes of 37W
- 10W for 1 hour
- 100 of these give 1 kWhr
- 45g each, so 1 kWhr weighs 4.5 kg.
- At this density, ultra light cars (500 lb total) - will have 30 miles per kwhr.
- 1kwhr ~ 4MJ - so about 1/10 kg gasoline. Given gas is 20% efficient in cars, we have 1/2 kg equivalent. Tbis gets us to about 240 mpg equivalent.
- With 1 kW solar added- that gets us to about 400 mpg equivalent.
Discharge Characteristics
- Can 18650 cells really discharge at 10A rate? Yes! [1] - Panasonic goes up to 20 amp rate. 6S (6 cell) packs are 22v. 10 of 6s cells, if discharged at 20A, give a 200A welder for 6 minutes. See Discharge Rate.
- Crappy ones can be as low as delivering 2.5A each - [2]. With 100 of these, that's still a 250A welder which has a weight of 5 kg for the batteries. Still impressive.
- Discharge rate of 20A yields temp increase to 50C - [3]
Specs
- Note actual spec from a buyer on Amazon - [4]
Reviews
- https://thegunzone.com/best-18650-batteries/
- https://www.18650batterystore.com/Best-18650-Battery-Guide-s/142.htm
Management
- While specs say 250 cycles for 15A discharge - Multiple thousands of cycles are possible when charged to 80% and drained to 30%. - [5]
Sourcing
- ~$3 each in packs of 40 - [6]
Cost Analysis
- From <$1 to $7 each - so choose wisely -
- Cheapest - [7]
- Best - Samsung 30Q - 3000 mAh - $3 in bulk - [8]
- From lifetime design perspective, 2000 cycles is only 3 years, though. If used daily - batteries last only 3 years.
Links
External Links
- Fantastic forms for recycling old 18650s into DIY Power Walls https://secondlifestorage.com/index.php
- Best rated battery and everything you need to know about 18650s - [12]