FVEAA Forums

Battery Charging and Electronic Technology => Li-Ion => Topic started by: john.emde on July 10, 2014, 07:09:32 PM

Title: To constrain Li-ion cells or not ?
Post by: john.emde on July 10, 2014, 07:09:32 PM

Li-ion cells expand as their State Of Charge reaches or passes 100 %.
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A  cell may be damaged if this expansion is not contained (due to layer separation).
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Most of the info here comes from sources unknown and was compiled from my notes and experiences over the years.  Reader discretion is advised.
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Title: Re: To constrain Li-ion cells or not ?
Post by: ted.lowe on July 11, 2014, 01:41:25 AM

Thanks John for sharing your EXCELLENT compilation!!!

Title: Re: To constrain Li-ion cells or not ?
Post by: ted.lowe on July 20, 2014, 03:25:56 AM

This looks like a source of some of John's compilation.  This is useful in understanding the 'constraining' or 'banding' or 'side clamping' issue in more detail.

http://liionbms.com/php/prismatic_tips.php (http://liionbms.com/php/prismatic_tips.php)

Title: Re: To constrain Li-ion cells or not ?
Post by: john.emde on July 20, 2014, 03:03:36 PM

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After working with Li-ion cells for some time now, I firmly believe that banding the cell stacks and using a BMS is the way to go. Protect your investment.
John

Title: Re: To constrain Li-ion cells or not ?
Post by: ted.lowe on July 21, 2014, 01:21:48 AM

Thanks John!  i think i decided today to band my cells, because it can't be that complicated or expensive, and what would it hurt (if it wasn't needed).  Seems like a simple cheap practice to follow.

Do you know what tools / supplies are needed or someplace i can have the cells banded affordably?  Thanks!

i haven't decided yet about the BMS, but doing lots of research and thinking on the topic!!

Title: Re: To constrain Li-ion cells or not ?
Post by: john.emde on August 10, 2014, 02:33:47 PM

 

Quote

"Do you know what tools / supplies are needed
or someplace i can have the cells banded affordably?"

Come to think of it.  Yes!   The guys at Build EV have the
knowledge and equipment to do the job.

Build EV  (630) 740-8826

Title: Re: To constrain Li-ion cells or not ?
Post by: john.emde on November 08, 2014, 05:44:42 PM

Included is a pic of part of the banding process.
The cells are stacked and aligned with plates at either end
and lightly pressed together to hold them in position.
Then usually 2 or more steel packing straps are tightened
around and crimped to hold it all together.

(http://www.fveaa.org/fb/cell_banding_395.jpg)

Title: Re: To constrain Li-ion cells or not ?
Post by: ted.lowe on November 08, 2014, 07:03:33 PM

Nice John, thx!