18650 Cells: Difference between revisions

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=What it it?=
https://www.google.com/search?q=18650+cells&client=ubuntu&hs=KUs&source=univ&tbm=shop&tbo=u&sa=X&ved=0ahUKEwj8xPLHwdLfAhULtIMKHTQ3ADUQsxgIKw&biw=1438&bih=738
https://www.google.com/search?q=18650+cells&client=ubuntu&hs=KUs&source=univ&tbm=shop&tbo=u&sa=X&ved=0ahUKEwj8xPLHwdLfAhULtIMKHTQ3ADUQsxgIKw&biw=1438&bih=738


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*18 minutes of 37W
*18 minutes of 37W
*10W for 1 hour
*10W for 1 hour
*30 of these give 1 kWhr
*100 of these give 1 kWhr
*45g each, so 1 kWhr weighs 1.5 kg.
*'''45g each, so 1 kWhr weighs 4.5 kg.'''
*'''4 kWhr is under 20 kg, and costs $1400''' - see below
*'''Continuous power is 14.8 kW (20 hp)'''.
*At this density, ultra light cars (500 lb total) - will have 30 miles per kwhr.
*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.  
*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.
*With 1 kW solar added- that gets us to about 400 mpg equivalent.
==Peak Performance==
*20A continuous is common, and max at 40A continuous.
*20A continuous means higher peak for a short time - 40A. That is 150W per cell for a short time! Such as passing in automotive applications.
*100 of these give 15kW peak - for 5 kg of batteries. This is high power density
*Each bat is $3, so for $900 you get 45kW peak power - sufficient for excellent performance on hybrid vehicles that have a small engine (5kW) and have much higher peak power for hills and passing (50kW).
*Solar cars as such become practical, with solar hydrogen power.
=Best Cell=
*Samsung 25R - [https://liionwholesale.com/products/samsung-inr18650-25r-battery-genuine-tested-20a-2500mah-flat-top-wholesale-lot?variant=31113493053509&utm_campaign=googleshopping1&gclid=EAIaIQobChMItOLb6fWo6wIVjobACh2cSgHmEAYYAiABEgJHR_D_BwE]. 20A continuous for 6 minutes at 3V. 60W cell. 100 of these are 6 kW, which make for a decent burst power source at 4.5 kg weight.
*Practical and affordable scenario - 12kW - 6 minutes of time at a weight cost of 9kg. $560. As part of an auxiliary hybrid drive train.
*[[Changfa Diesel]] costs 180kg in weight - so is much heavier.
=Discharge Characteristics=
*Can 18650 cells really discharge at 10A rate? Yes! [https://batteryuniversity.com/learn/article/discharge_characteristics_li] - 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 - [https://www.rcgroups.com/forums/showthread.php?2120900-How-do-you-know-how-many-amps-an-18650-LiPo-can-safely-discharge]. 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 - [https://batteryuniversity.com/index.php/learn/article/discharge_characteristics_li]


=Specs=
=Specs=
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*While specs say 250 cycles for 15A discharge - Multiple thousands of cycles are possible when charged to 80% and drained to 30%. - [https://electricbikereview.com/forum/threads/e-bike-battery-guide.24443/]
*While specs say 250 cycles for 15A discharge - Multiple thousands of cycles are possible when charged to 80% and drained to 30%. - [https://electricbikereview.com/forum/threads/e-bike-battery-guide.24443/]


=Cost=
=Sourcing=
*Samsung 30Q - $3.75 - [https://www.18650batterystore.com/Samsung-18650-p/samsung-30q.htm]. This says 15A rated and 50W continuous max - 15A for 12 minutes. [https://liionwholesale.com/collections/batteries/products/samsung-inr18650-30q-battery-15a-3000mah-flat-top-wholesale-discount-genuine-and-tested?variant=2915614724]
*Sample - $1420 total with shipping for 400 batteries, '''4 kWhr, 20 kW for 12 minutes continuous rating'''. May be relevant for a power cube application. [[File:epowercube.jpg|200px]]
 
=Cost Analysis=
*From <$1 to $7 each - so choose wisely -  
*From <$1 to $7 each - so choose wisely -  
*Cheapest - [https://www.ebay.com/itm/Lot-100X-UltraFire-3-7V-18650-3000mAh-Li-ion-Rechargeable-Battery-For-Flashlight/152775669854?_trkparms=aid%3D555018%26algo%3DPL.SIM%26ao%3D2%26asc%3D20160908110712%26meid%3D55b6eb4cf8af45d2a3c06c30cd407496%26pid%3D100677%26rk%3D2%26rkt%3D30%26mehot%3Dpp%26sd%3D222653268869%26itm%3D152775669854&_trksid=p2385738.c100677.m4598]
 
*Best - Samsung 30Q - 3000 mAh - $3 in bulk - [https://www.ebay.com/i/273586773978?chn=ps]
*Best - Samsung 30Q - 3000 mAh - $3 in bulk - [https://www.ebay.com/i/273586773978?chn=ps]
:*These appear to be on spec at 3000 mAh - [https://www.youtube.com/watch?v=usmxQPhUL9s].
:*These appear to be on spec at 3000 mAh - [https://www.youtube.com/watch?v=usmxQPhUL9s].
:*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. In practice - 10 year max is likely. Not a good solution environmentally.
=20A Continuous=
*This one says it's 20A continuous - [https://liionwholesale.com/products/lg-hg2-18650-battery-genuine-tested-20a-3000mah-flat-top-wholesale-discount?variant=31166781554757]
*See ratings link for 30A continuous
*'''20A continuous and best seller- Samsung 25R 18650 - [https://www.18650batterystore.com/18650-p/samsung-25r-18650.htm]'''
=Links=
*Ratings of 18650 batteries - [https://www.18650batterystore.com/Best-18650-Battery-Guide-s/142.htm]
*[[21700 Cells]]
*[[Arduino Battery Chargers]]
*[[18650 Battery Packs]]
*[[Battery Pack SMEs]]


=External Links=
=External Links=
* Fantastic forms for recycling old 18650s into DIY Power Walls [[https://secondlifestorage.com/index.php]]
*[https://en.wikipedia.org/wiki/List_of_battery_sizes#Lithium-ion_batteries_(rechargeable) The Wikipedia Page on 18650 Cells]
*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 - [https://commonsensehome.com/18650-battery/]
*[https://www.youtube.com/watch?v=tKg-jIrr_JE A Video by the YouTube Channel "Teaching Tech" Titled "Beginner’s guide to building safe 18650 batteries" ] (Goes over basics of 18650 Cells, and design process guidance from their experience (Also lots of useful links/mentions) )
 
[[Category: Energy]] [[Category: Battery]]

Latest revision as of 22:38, 9 January 2022

What it it?

https://www.google.com/search?q=18650+cells&client=ubuntu&hs=KUs&source=univ&tbm=shop&tbo=u&sa=X&ved=0ahUKEwj8xPLHwdLfAhULtIMKHTQ3ADUQsxgIKw&biw=1438&bih=738

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.
  • 4 kWhr is under 20 kg, and costs $1400 - see below
  • Continuous power is 14.8 kW (20 hp).
  • 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.

Peak Performance

  • 20A continuous is common, and max at 40A continuous.
  • 20A continuous means higher peak for a short time - 40A. That is 150W per cell for a short time! Such as passing in automotive applications.
  • 100 of these give 15kW peak - for 5 kg of batteries. This is high power density
  • Each bat is $3, so for $900 you get 45kW peak power - sufficient for excellent performance on hybrid vehicles that have a small engine (5kW) and have much higher peak power for hills and passing (50kW).
  • Solar cars as such become practical, with solar hydrogen power.

Best Cell

  • Samsung 25R - [1]. 20A continuous for 6 minutes at 3V. 60W cell. 100 of these are 6 kW, which make for a decent burst power source at 4.5 kg weight.
  • Practical and affordable scenario - 12kW - 6 minutes of time at a weight cost of 9kg. $560. As part of an auxiliary hybrid drive train.
  • Changfa Diesel costs 180kg in weight - so is much heavier.

Discharge Characteristics

  • Can 18650 cells really discharge at 10A rate? Yes! [2] - 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 - [3]. 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 - [4]

Specs

  • Note actual spec from a buyer on Amazon - [5]

Reviews

Management

  • While specs say 250 cycles for 15A discharge - Multiple thousands of cycles are possible when charged to 80% and drained to 30%. - [6]

Sourcing

  • Samsung 30Q - $3.75 - [7]. This says 15A rated and 50W continuous max - 15A for 12 minutes. [8]
  • Sample - $1420 total with shipping for 400 batteries, 4 kWhr, 20 kW for 12 minutes continuous rating. May be relevant for a power cube application.
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Cost Analysis

  • From <$1 to $7 each - so choose wisely -
  • Best - Samsung 30Q - 3000 mAh - $3 in bulk - [9]
  • These appear to be on spec at 3000 mAh - [10].
  • Cycle life and specs - [11] - 250 cycles to 70% of rated
  • 1000 cycles at 6A discharge rate bottoming at about 60% capacity for 2000 cycles? - [12]. So these last pretty long.
  • From lifetime design perspective, 2000 cycles is only 3 years, though. If used daily - batteries last only 3 years. In practice - 10 year max is likely. Not a good solution environmentally.

20A Continuous

  • This one says it's 20A continuous - [13]
  • See ratings link for 30A continuous
  • 20A continuous and best seller- Samsung 25R 18650 - [14]

Links

External Links