Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
They’re rated at 600 mA·h, as are the much shorter 2/3 AA NiMH cells I also used for those phone packs:
Norelco T770 – rebuild
That’s a wrap of Kapton tape around the cells, plus a block of closed-cell foam to fill the cell holder. It’s not a high-stress environment, so this hack-job repair should work fine.
The trimmer’s charge / discharge cycle remains hostile to NiMH cells and I don’t expect a great lifetime from the new cells, either…
One of the batteries on the ancient Dell Inspiron 8100 laptop died completely and our Larval Engineer reports the other battery isn’t far behind; it gets her from outlet to outlet and not much more. Pursuant to that comment about harvesting reasonably good cells from dead batteries to build an extended-life external battery for the Canon SX230HS camera, I made a preliminary pack probe.
The label says it’s a 14.8 V battery, so you’d expect four 3.7 V lithium cells in series. The 3.8 A·h capacity suggests parallel cells:
Dell 75YUF battery – label
Indeed, peeling off the label shows four cells pairs in series:
Dell 75YUF battery – under label
The case joint seems firmly welded together and resisted simple attempts to crack it open. I might run a slitting saw around the edge, although I’ll probably just crunch it in the vise because the patient need not survive the operation.
A single cell should have a 1.9 A·h capacity, although in an awkward cylindrical form factor. The 3.5 A charging current would drop to 1.7 A for a (string of) single cells.
The Canon SX230HS uses a single 3.7 V, 1.1 A·h prismatic “battery”, which means replacing that with a single external cell wouldn’t be a major win; the size difference shows how much lithium energy storage tech has advanced in the last decade or so. A pair of cells in parallel would quadruple the runtime, which might be enough. Three in parallel would be fine, although that would require attention to matching their capacity; the nominal 5.2 A charging current (1.5 × 3.5 A) seems aggressive.
A long-forgotten toy emerged from the heap bearing a trio of corroded NiMH cells between the usual plated-steel contacts:
Corroded contacts – original
The toy wasn’t worth salvaging, but I extracted the contacts and applied Evapo-Rust to see what happened. After an overnight soak, some corrosion remained:
Corroded contacts – after Evapo-Rust
Scrubbing with a stainless-steel detail brush removed the flakes and left reasonably clean metal behind:
Corroded contacts – after brushing
Although it’s not beautiful, I think the contacts came out as well as one could expect. The longer contact plate has holes, thinned sections, and some corrosion inside the spring; I’d be mildly tempted to rebuilt the whole thing with some nickel shim stock and a new spring.
If I were salvaging the toy, I’d dab vinegar on the wiring to neutralize the creeping potassium hydroxide, rinse the whole thing with water, and clean out the case. Instead, it joined the consumer electronics recycling box with a thud…
The front brake on my bike started sounding more gritty than usual on a recent ride, which led to pulling the pads off, which led to discovering that one pad had worn completely through:
Worn-through brake pad
The rim had a slight scuff where that aluminum tab stuck through, but nothing worth worrying about. The wear indicators aren’t reliable, because the pad curve matches 27-ish inch wheels and the Tour Easy has a 20 inch front wheel. If you align the pads to the outside of the rim, as I do, the inside edge gets light wear. So I let ’em wear, check them when the tire gets a flat, and this is the first time a pad has worn through. I think that means the front tire hasn’t had a flat in quite a while…
While I was at it, I replaced all the pads on both our bikes. The rear pads didn’t have nearly as much wear, which is about what you’d expect, although the wear indicator grooves have just about bottomed out:
Worn replaceable pads
Those are replaceable pads, which work quite well on the new brake arms. I suspect by the time I get around to needing new inserts (I bought a bunch, of course) they’ll be obsolete and unobtainable.
I file the pads flat to save a bit of time wearing them in:
Filed replaceable pads
I don’t hold with the notion of toeing in the pads to avoid squealing, vastly preferring crisp brakes with very little travel. Whatever the material is in Aztek pads, they don’t squeal after they’ve fitted themselves to the rim… but, of course, this new pair howled worse than the Freezer Dog when I got them out on the road.
Squealing brakes aren’t entirely a bad thing, as they scare the daylights out of oblivious pedestrians, but I’d rather use the bell. So I gripped a strip of fine sandpaper between pad and rim, gently squeezed the brake lever, and rolled the bike about two wheel revolutions. Repeat on the other side and the rim’s now nice and clean and grippy. Flip the sandpaper over, scrub the pad surface, and they don’t make a sound.
When I bought a new belt some months ago, I thought the lack of stitching meant it was made from a single strip of leather. Come to find out that it’s actually two strips glued together with something sticky that came un-done at the point where the belt passes through the buckle.
So I peeled a bit more apart, smoothed a thin layer of urethane glue (aka Gorilla Glue) inside, laid waxed paper on both side just in case the foam expanded beyond my wildest imagination, and clamped it together:
Belt clamping
The glue layer turned out just about perfect, with only a few blobs sticking out the sides:
Belt with urethane glue blobs
Those blobs snapped off easily enough and the belt works fine again. We’ll see how long this one lasts…
Actually, that NIC didn’t slip right into place, because its backpanel plate was sized for a full-height PC case. Unlike the cheap stamped steel you find these days, NetGear used much thicker metal that required an attack with the bandsaw, a hammer, and some files to clean up the raw edges.
But it fit pretty well after all that:
Shortened NIC backplate
You can just barely see the NetGear logo wrapped around the right-angle bend…
The Smell of Molten Projects in the Morning 