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18650 battery info
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18650 battery info

by Stsguy on Mon May 10, 2021 12:25 am

I'm no knowledge bunny on this subject but I'm crazy enuff to tackle a project. I need some help on the 18650
I have 2 things that came to y bench 1st old Makita battery packs., I want to rebuild em.. I bought a spot welder .. it's on the way now.. i need to buy or locate the right batteries to buy
18650VT is the 1st project but there are so many different 18650 batts out there. and there are not the easiest thing to find. if you try to match the battery and so many are selling pull-outs. I'm worried Ill get ripped off. Brand: Sony
Model: US18650VT
Capacity: 1300mAh Rated
Voltage: 3.60V Nominal
Charging: 4.20V Maximum
1300mA Standard
--- mA Maximum
Discharging: 2.75V Cutoff
260mA Standard
--- mA Maximum
Description: Green Cell Wrapper
Black Insulator Ring
18650 Form Factor
How far can I get off the specs above and still be ok on performance

Also, I have a yunecc Skate board. it holds 21 18650 batteries NCR18650 pf Specifications:
Model: NCR18650PF
Size: 18650
Style: Flat Top
Chemistry: NMC
Nominal Capacity: 2900mAh
Continuous Discharge Rating: 10A
Nominal Voltage: 3.6v
Protected: No
Rechargeable: Yes
Approximate Dimensions: 18.50mm x 65.30mm
Approximate Weight: 46.5g
I have trouble finding a good source that's also cost-effective.
Can I wavier off the specs. and anyone know where to buy..CHeers Joe

Stsguy
 
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Joined: Sat Aug 24, 2019 3:20 pm

Re: 18650 battery info

by adafruit_support_mike on Mon May 10, 2021 11:38 pm

The short version is: don't.

LiPos normally operate on the boundary between 'energy storage' and 'incendiary device', are extremely picky about their charge and discharge cycles, and provide no useful information to show that they're about to catch fire. Using them safely is all about following known best practices.

The best practice for combining lithium cells into a battery pack is to use new cells from the same production lot whose characterization tests match to within a few millivolts. Those are packed together and spend their whole lives in nearly identical operating conditions, so they can be expected to age in nearly identical ways. The only cost effective way to do all that is at the factory where they have large populations of cells they can cherry-pick for good matching, and lots of specialized test equipment.

Once lithium cells have seen use in the real world, it's functionally impossible to match them well enough to work in parallel or in series without continuous monitoring. The best thing you can say about a DIY assembly is, "it hasn't exploded yet."

Instead of trying to do the impossible with a high chance of a very bad outcome, you can build systems with electronics to continually monitor the cells. We don't happen to carry anything in that line, but there are control boards specifically designed to charge individual cells, make them work as a single battery, and keep everything operating safely.

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Please be positive and constructive with your questions and comments.