Generic Sony NP-FS11 Battery Packs: Surprising Contents Thereof

So I dismantled the three junk packs I got from halfway around the world and rebuilt them with better-quality cells. Search for NP-FS11 and you’ll find the rest of the story.

Some observations…

These cases are the thinnest plastic that doesn’t actually break when you pick it up: to crack the case seam, you must push firmly. Two of the three packs were already cracked and the third yielded to a slight squeeze.

What’s inside? Welly, welly, welly, what do we have here?

DOA Battery Contents
DOA Battery Contents

The cells are labeled Sony Energytec, which ought to be a reputable brand name. Some possibilities:

  • Counterfeit cells
  • Quality test rejects

I don’t know why you’d bother putting counterfeit cells inside a generic case; it’d be more profitable to sell a completely counterfeit battery with a fancy Sony label. So I’m guessing these came from a batch of cells that failed inspection and were miraculously saved from destruction.

Battery Protection Circuit Board
Battery Protection Circuit Board

They have the usual protection circuit board on the top. What’s a bit tricky is that you must unsolder the three leads connecting to the case terminals before you can extract the cells. I unsoldered the strap from the negative terminal while I was at it; the positive lead is inaccessible beyond the black IC on the left.

After that, it’s a straightforward rebuild.

6 thoughts on “Generic Sony NP-FS11 Battery Packs: Surprising Contents Thereof

  1. I’ve been musing on this. I agree that making fakes to hide in a battery case seems unlikely. I doubt a company is making fake Sony cells that are then bought by no-name pack manufacturers. Your thought that they may be genuine Sony products that got rejected but not trashed makes sense. And I have two other hypotheses. One is that they are genuine Sony cells that wore out, were stripped from another pack, the truly dead ones discarded, and the remaining ones built into “new” packs – recycling of a sort. Another is that they are fakes, and the manufacturer needed plastic stink tubing to insulate the cells from each other anyway, and “acquired” some of the Sony-marked stock on the cheap and used that. I’m trying to think of forensics you could employ to corroborate or refute any of these ideas. I just discarded a cache of similar (likely genuine) cells, I wish I had checked them for date codes. I wouldn’t be surprised if genuine Sony cells had date or lot numbers. Do you know? Do these? If so, if the date codes are decipherable, it would be interesting to see if they’re old (which would support the “recycle” theory). If they’re unmarked (and should be marked) it would support either the “reject” or “stink tubing” theory.

    1. stripped from another pack

      The weld nuggets on the cells match up neatly with the current nickel strips, so there’s no evidence these cells had a previous and more productive life.

      Of course, they could have un-soldered the entire assembly (cell pair + nickel strips) from a used-up Big Name battery and plunked it into a (new) cheap case, but that makes no sense at all. The cases are definitely not Big Name quality, unless Big Name has vastly cheapnified its offerings. Why not just strip the sticker off the Big Name case and relabel it?

      The protection circuit has no identifying marks.

      “acquired” some of the Sony-marked stock on the cheap

      That would make sense. The lot numbers / date codes printed on the cells under the wrap are uninformative gibberish: YIC10C, SET YJH22W, and 2YGH28P. The two cells in each battery had the same codes, so there’s evidence of an intent to match the cells. The font / print size varies slightly between the cells, but the print quality is pretty good.

      Many things are possible in a facility with essentially zero labor cost, negligible material cost, and no pesky warranty obligations. The only explanation that makes sense is that they’re deliberately shipping junk in order to get dollars in hand, having figured out that nobody will come after them for a six-dollar transaction. They can afford to send replacement cells to anybody who complains, simply because essentially nobody has the facilities to verify the capacity.

      1. Ah, the welds are a good piece of evidence. And you’re right, this is a very common (and workable) business model. Even big businesses with customer support and warrenties generally have the policy to just send out replacements if anybody complains, as it costs little (less than investigating in detail), generates customer goodwill, and like you said, most people won’t complain anyway. I may follow your lead and order a dozen or so packs from various places and characterize them, as it would cost about the same as one name-brand pack. I’d have to build the gear myself as the commercially available stuff only works with windows and they (idiotically) refuse to document the protocol, but it’s pretty simple stuff.

        1. I have a back-burner project to build a battery rundown tester that would handle 4 or 8 single cells in parallel, so you could find the weak cell in a pack without waiting a week for the results.

          Probably an Arduino Mega (with enough PWM / ADC channels) driving a handful of FETs with current-sense resistors to the ADCs. Low voltages, low currents, and nothing fancy. I think constant current is good enough; it’s close to constant power until the very end of the curve when the cell’s pretty much drained anyway.

          The West Mountain Radio CBA dumps data every second, which is absurd. Maybe once a minute, tops, plus when any channel changes by one count. Something like that.

          If you do it first, write it up!

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