Sunday, September 1, 2013

Strapping the Cells

In the earlier days of DIY lithium conversions, conventional wisdom was that batteries needed to be tightly strapped - even so far as using threaded rod and metal plates to compress them together.  It was believed that this prevented bulging - kind of like keeping the smoke from escaping.  It turns out that bulging is entirely avoidable - just don't abuse your cells with over-charging or over-discharging.  However, it is convenient mechanically to group the cells together.  It makes it easier to load them in the racks, too.  So I got some poly strapping equipment and banded most of the cells in groups of 3, 4, or 5.

Use is pretty straightforward.  Place a length of strap around the thing you want to bind, and put a metal clip in place, then thread the strap through the ratcheting strapping machine:

Tension the strap as desired (being careful not to over-tension), and then crimp the metal clip (you can also see the crimper on the work bench at the right of the picture above):

Once crimped, press the lever on the ratchet down to cut the band:

This strapping will not hold much weight, so I don't recommend it as the only battery support mechanism, but it does keep things in place nicely while assembling packs.

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