Dissecting third-party camera batteries, part 2: Swelling

It’s not uncommon for a midsection to become distended with advancing age. But when it happens to a battery, it can be quite problematic. The post Dissecting third-party camera batteries, part 2: Swelling appeared first on EDN.

Electronics Aug 10, 2026 0 4 Add to Reading List

Dissecting third-party camera batteries, part 2: Swelling

It’s not uncommon for a midsection to become soft and distended with advancing age. That said, when it happens to a battery, it’s potentially quite problematic.

In last week’s part 1, I took apart a third-party BLX-1 battery which had come with my Olympus (now OM System) OM-1 digital camera and which the manufacturer’s own BCX-1 charger refused to recognize as a valid recharge partner. Also recently augmenting my burgeoning gear inventory are two enthusiast-prized Olympus PEN-F Micro Four Thirds bodies (once again digital, not the film-based precursor), one in each color option offered by the manufacturer a decade ago when they were new.

Each came with a third-party BLN-1 battery (7.6 V, 1220 mAh). Supplier names differed but their physical appearances were identical, therefore suggestive of a common manufacturing source. I’ll be taking them both apart today to test my hypothesis. But why am I dissecting them at all?

Unlike the BLX-1, they seemingly still work fine, but they both arrived slightly swollen, with further distension likely after additional use and recharge cycles. The last thing I want is for an inexpensive, replaceable cell to end up permanently lodged in the battery compartment of an expensive, irreplaceable camera, so retirement and replacement was a priority for both!

Trust me when I say that all the cameras showcased in this two-part series are Micro Four Thirds models, Olympus-now-OM System to boot, is only a coincidence. I’ve had no shortage of mixed-at-best success in the past with third-party batteries for other manufacturers’ cameras, too.

Some Wasabi with your sushi?

I randomly picked the one from Wasabi Power, a common “clone” cell supplier, to disassemble first. As usual, I’ll start with some overview shots, accompanied by a 0.75′′ (19.1 mm) diameter U.S. penny for size comparison purposes. Top.

Bottom.

Four of the BLN-1 contacts—”+”, “-“, “I” and “T”—are marked the same (albeit in different ordering) as with the BLX-1. As I mentioned last time, published specifications for batteries like these are hard-to-impossible to come by, given that for various reasons the camera manufacturer doesn’t want to encourage third-party cloning.

That said, once again the functions of “+” and “-“ are likely related to the applied voltage and current involved in the fundamental cell-charging and -discharging (for camera powering) functions. “I”, typically standing for “information” or “identification”, references the interrogation initially done by both charger and camera after battery insertion and power-on, and ongoing from that point on, presumably implemented by a bidirectional single-data-pin serial communications protocol of some sort.

“T” typically references “temperature”, with the contact connected to an embedded negative temperature coefficient (NTC) thermistor or other sensor that monitors the internal cell(s) and alerts the charger to potential overheating. And this time there’s a fifth electrical contact, “S”. User research suggests that it was added in response to Japanese standards body guideline revisions that mandated a fuller shut-off of the accompanying charger after the battery reported it was “full”, thereby minimizing subsequent “vampire” power draw.

The BLX-1 battery disassembled in part 1 of this series is significantly newer in generation than the BLN-1 and presumably integrates this function along with others already supported over the “I” interface, thereby negating the ongoing need for a dedicated “S” contact.

Onward, redux. Once again, the other end is much less exciting, as are the sides.

Ongoing unexciting-dissection aspirations

And once again, a Sirens-like tempting, albeit ultrasonic-welded, seam around the battery’s circumference seems to be the most feasible pathway inside, the potential for sparks, smoke, flame, and other calamities aside. Danger, Will Robinson!

Phew!

This time, the batteries’ form factors aren’t cylindrical and plastic-covered as before, but rectangular and metallic; niftily-named prismatic, to be exact. Once again throwing caution to the wind, I pressed forward determinedly (albeit cautiously) with the disassembly.

Rubber strips again, this time tape- and paper-accompanied, to insulate the mini-PCB from the batteries’ terminals both mechanically and electrically.

Enough with the teasing; I know this is what you’re most interested in seeing, right?

The design is much more elementary than with the BLX-1 circuit board we saw in part 1. The eight-lead IC PCB-labeled as U2 is stamped as follows on top, below a cryptic company logo.

8822
E6H01

It’s another dual N-channel MOSFET. And then there’s six-lead U1 to its right, marked as follows.

CGKU

As with the BLX-1, per an earlier-referenced discussion, I’m guessing it’s a rudimentary battery-protection IC. Apparently recharge-balancing the two cells isn’t of concern in this specific case.

Speaking of which, let’s take a closer look at the markings on the two cells’ prismatic cases, which you’ve already glimpsed in prior images.

They match each other, and I suspect the last eight characters of each reference a September 2016 manufacturing date. Nearing 10 years old, I’m willing to forgive a bit of old-age swelling, no matter that it obviates any further use (that I’m comfortable taking a chance on, at least). No voltage or capacity specs; that said, I suspect they’re the relatively common 4.2 V (3.7 V nominal) variant in a serial-interconnect topology.

Testing a common-sourcing hypothesis

Now for its Newmowa-branded counterpart (is that a clever company logo, or what?), complete with scribbling on top from its prior owner (who apparently, like me, is also blessed to own a diversity of camera hardware models from various manufacturers, and needs to keep his batteries straight).

Trust me when I say that had I decided to keep the battery in service, cleaning off those contacts would have been my very next step!

Once more unto the breach, dear friends.

This time, interestingly, both cells’ cases are completely marking-free on both sides.

Although the means by which the cells are adhesively bonded both to each other and to the surrounding halves of the enclosure differ, there’s visually obvious commonality with respect to the respective mini-PCB layouts.

That said, the components are seemingly divergent from a sourcing standpoint (albeit functionally identical, at least likely). Here’s what’s atop eight-lead U2 this time:

SNE
5N20V
7H09 (don’t quote me on the accuracy of this last line; it’s pretty fuzzy)

Once again, it’s a dual N-channel power MOSFET. And six-lead IC U1 to its right? Again, don’t quote me definitively, but here’s my best shot post-cleanup with rubbing alcohol.

20DD
L607

And with that, after wrapping up all four cells (two from each of the two batteries) in insulating masking tape to ensure safe storage until after my writeup is published.