The Roku Remote

I feel like I might want to add some constructive criticism, about the new playback device, of which I just bought one, as described in this posting.

The designers have made some progressive statements in how they designed this hardware, that range from only taking up circuit-board space with modern, HDMI output, to designing a novel remote-control. I think that although I like many of the concepts that wen into the remote, there is some room for improvement.

This remote has a headphone-jack, so that we do not need to plug any headphones into our TV or into our stationary devices, which may be located on the other side of the living room, from where we sit. The first thing I would typically test about that, is whether the sound from the TV actually does mute, when we plug in headphones. And in fact, this works as it should.

That headphone jack came bundled with headphones for me to use, right out-of-the-box. I suppose this comment might seem petty, considering that this is a standard jack, into which I could plug an any headphones I supply. But in the included headphones, the Right ear-piece could be labeled more clearly, to distinguish it from the Left ear-piece. They look nearly identical, and the tiny ‘R’ stamped into the Right piece, might be hard for people to read, whose vision is not 100%.

Okay, but now I am done with the trivial details.

The remote has 4 pre-assigned buttons, for 4 possible channels, which the designers felt that their users would want to visit most-frequently. Netflix is one of them, but there are 3 more. These buttons save us the possible hassle, of navigating a menu, to the channel we want to view most-frequently.

The problem with this is, that depending on what a certain user prefers, the other 3 channels might not be set up. They are, as usual, free to install, but then we need to enter the log-in information into our , to connect to each of the accounts. What if we do not have these accounts? For example, ‘‘ was randomly chosen to deserve a button on its own, and yet I would find it impractical to set up a account, to use for the duration.

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Measurement of 18650 Batteries and Conclusion

I have now received my “9900mAh, 3.7V” batteries, and their bundled “4.2V” charger, which I first wrote about in this earlier posting. After receiving a full charge, their measured voltage while still inserted was 4.215V , immediately after removed at no load 4.195V , and after standing for 30 minutes, at no load, 4.138V . When new they require approximately 4h + 5min to charge.

I have to conclude that these batteries do not contain any series-connected, internal, over-voltage-protection chip. They seem to be based on the Layered Lithium-Manganese-Oxide:┬áLi2MnO3 . They differ from the “3400mAh, 3.7V” variety, in that the other kind are based on the Spinel Lithium-Manganese-Oxide: LiMn2O4 .

I must only use this charger, with the batteries it shipped with.

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Why we see voltage inconsistencies, with Li-Ion Batteries

I use lithium-ion batteries, which I abbreviate to Li-Ion, the same way other people use them. But I have noticed that the fully-charged voltage of each one is not the same.

There is a WiKiPedia article, which explains well enough for my needs, how Lithium-Ion batteries work. One question which I had not previously had an answer to, was, ‘If I was to design a Lithium-Metal battery, aside from using Lithium as the anode, what material would I use as a cathode – as the oxidizer?’ And the above answer provides possible solutions.

One fact which I have noted before, is that I have ordered a battery charger from Ebay, for ‘Type 18650′ batteries, and that these batteries usually have a fully-charged voltage of 3.7 Volts, and that some compatible batteries only hold 3400mAh of charge, while others hold 9000mAh of charge.

Well, when the battery in my phone has a voltage of about 3.7V, it is only indicated as 60% charged. At 90% charged, my phone battery has 4.1V, and a typical charging-cycle will bring it up to 4.2V – enough to fry certain other batteries.

All of these observations could well be explained, by the phone battery being a Lithium-Cobalt-Oxide battery, while certain other, exchangeable batteries may simply be Lithium-Iron-Phosphate batteries, or yet other batteries. ‘Other exchangeable batteries’ could include the ones in my camera, etc.. The fact that the cathode can have different compositions, will lead to different voltages.

But, when I do receive the batteries and charger I ordered, which are supposed to have a 9000mAh capacity, I will need to verify something. The Type 18650 batteries need to have a fully-charged voltage of 3.7V . Yet, there seem to be high-capacity batteries which hold more charge than merely 3400mAh.

There is a possible, little trick which the makers of my battery and charger could be using. They could have programmed their charger, only to charge the batteries to 3.7V – as usual. But the high-capacity batteries there, too, could be of the Lithium-Cobalt-Oxide type, which can theoretically be charged to 4.2V. At 3.7V, that charger could simply stop charging them.

When I have received my charger and the batteries, what I will have to do after charging those, will be to measure their voltage. The reason for this will be the fact that other battery-types are only allowed to be charged to 3.7V . I will need to know whether it would be safe to insert a Lithium-Iron-Phosphate battery into the charger, instead of the higher-capacity batteries it ships with.

(Edit 12/11/2016 : Additionally, I will want to measure the voltage of the same battery, 30 minutes after taking it out of the charger, without having connected any load to it. I could expect, to see a voltage of 4.2V , and then one of 4.1V . This would tell me that the same charger cannot be used with the lower-capacity batteries. But all of this thinking is pure guesswork, until I have measured the battery. I am insinuating that the batteries are mislabeled as 3.7V batteries, and as soon as something is mislabeled, we need to measure values. )

If the yet-to-arrive batteries test out as having 3.7 V or close to it, I will also know that I can trust the charger I ordered, with the lower-capacity battery-type, which it does not ship with.

Dirk

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