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Comment: Re:Too good to be true (Score 1) 243 243

NiMH and NiCd do have very similar discharge curves for comparable "C" discharge rates. (If you discharge a NiCd at a rate that will discharge it in three hours (to pick a rate), the discharge curve will look very similar to a NiMH being discharged at a rate that will discharge it in three hours. The differences you do see will mostly come from different internal resistances.)

some rare or non-relevant circumstances

What are you talking about? I'm talking about NiMH discharge curves, all of them, not some "rare or non-relevant circumstance".

I'm sorry that you got your information from an incorrect web page, but you did -- NiMH cells start at 1.41 volts, not 1.22 volts, and the discharge curve you explicitly linked to does not represent reality.

This demonstrates a lack of common-sense on your part, nothing else.

Again, I'm sorry that you got some bad information, but you did, and I've shown it to be bad with many different sources.

What would show a "lack of common sense" would be a failure to acknowledge that you repeated some incorrect information, learn from that, correct it, and move on.

Comment: Re:Too good to be true (Score 1) 243 243

Looking at the discharge curve given in the Energizer pdf, page 6, for NiMH NH15 AA battery being discharged at 750 mA with 10 mA pulses ... the battery finally hits 1.2 volts right at about 60% discharge at the 750 mA discharge rate, and about 1.22 volts during the 10 mA "pulses".

The exact voltages depend on discharge rate -- higher discharge rates give you a lower voltage, but at a low discharge rate (around a C/20 discharge rate), the battery hitting 1.22 volts when 60% discharged is approximately what that charge shows. And even at a higher rate -- C/3 -- it finally hits 1.20 volts when about 60% discharge.

And yet the discharge curve that chihowa linked to had the NiMH cell *starting* at about 1.24 volts, then going down to 1.2 volts, then *going up slightly* before going down again -- *THAT* is pulling it out of your backside.

I linked to dozens of discharge curves, done at various rates with various batteries, but in general you'll find that when the cell finally hits 1.20 volts, it's roughly 50% discharged, with the exact voltages and discharge amounts depending on the discharge rate and the exact battery involved.

For example, looking at this specific one -- looking at the 0.2C discharge curve (0.2C means that the battery is fully discharged in five hours), when the battery is 60% discharge thed voltage is about 1.23 volts.

Comment: Re:Too good to be true (Score 1) 243 243

That discharge curve you posted lacks context. What's the discharge rate? What battery?

And unfortunately, the source page does not provide these details either, basically making the chart useless. In fact, I suspect that the author just drew it freehand rather than actually measuring it? Certainly, his starting voltage is flat out *wrong* and his curve seems too flat. (In fact, he has the NiMH voltage *increasing* slightly during parts of the discharge period!)

Here's a better reference, with a much more useful discharge curve on page six. This is for a specific battery (Energizer NiMH NH15 AA) at a specific discharge rate (750 mA with a pulse (presumably the pulse is to remove the effect of the internal resistance when measuring and to simulate a low discharge rate -- which I would call slightly misleading, but they did disclose it.) Note the starting voltage of a bit over 1.4 volts, and note that once the battery hits 1.2 volts ... it is indeed about halfway discharged.

If you'd like to see a bunch more *real world* NiMH discharge curves, here you go. Keep in mind that they're not all for a single cell, but those that are start at a bit over 1.4 volts for lower discharge rates and a bit under 1.4 volts for higher discharge rates. And here's the alkaline discharge curves to compare to.

Self-discharge alone will drop most NiMH/NiCd cells to below 1.4V pretty quickly.

They do have a significant self discharge rate -- but still, they start at 1.41 volts, not 1.22 volts. And the low-discharge rate NiMH cells (like the Eneloops) have *greatly* reduced the self discharge rate.

Either way, if you were trying to explain why primary batteries are rated based on their starting voltages and primary batteries on their "middle of their discharge curve" voltages ... you didn't really succeed. The real world discharge curves for NiMH and alkaline batteries look pretty similar, but why should we look at the very highest point for alkalines and the middle point for NiMH beyond "that's the way it's always been done" ?

Comment: Re:Too good to be true (Score 2, Informative) 243 243

otherwise it does not work with NiMH accumulators which only have 1.22V when fully charged

No, NiMH and NiCD cells are at 1.41 volts when fully charged. By the time they hit 1.22 volts, perhaps 60% of the energy that was in the battery is gone.

I do not know why primary cell voltages are given at their very highest possible voltage and secondary cell voltages are given approximately at the middle of their useful range -- it basically turns the "1.5v vs 1.2v" thing into an apples to orange comparison, when saying "1.5v vs 1.4v" would be far more accurate.

That said ... how useful this device would be would depend on the application. If a device will stop working when the battery gets down to 1.3 volts ... yes, this device could help a lot, especially with NiMH cells that start at 1.4 volts rather than alkaline's 1.5 volts. But that's a poorly designed device that will leave a lot of battery power unused.

But, if the device will work until the battery gets down to 0.9 volts ... there's not much energy left, and this device can not possibly help much.

Comment: Re:What it really says... (Score 1) 184 184

And no, I do not use spinning media as a backup. I use tapes. Using spinning media for proper backups is almost impossible. See http://www.taobackup.com/

Your link doesn't really seem to explain how using "spinning media for proper backups is almost impossible", so you'll either need to point to exactly where it says that, provide some other reference, or expand on that on your own.

Comment: Re:Found in small town, CA? (Score 3, Informative) 83 83

1x is digital too.

It does have longer range than 3G and 4G, and so it could very well be that you were simply getting a marginal signal and there was no Stingray involved at all -- your phone just used the best that was available, and that was 1x.

And once you left, the 4G signal got strong enough again to use, and your phone switched back.

Comment: Re:misdemeanor?? (Score 1) 271 271

Lots of misdemeanors can result in law enforcement using deadly force on you.

That said, I would expect his autogyro to be considered an ultralight and not require registration, though maybe it's too big to qualify? Also, if it is an ultralight, then he doesn't need a license to fly it.

It's also not equipped with a radio or transponder, though I don't know how required those are or what the penalties for not having them would be -- though a felony seems too strict.

Comment: Re:A Recognition Algorithm That Outperforms Humans (Score 1) 91 91

Don't crash into anything while moving from point A to point B is a fairly unambiguous goal which computers should be able to handle, even if the details in reality are fairly complicated.

Given the number of computer games I've played with horrible pathfinding ... I'm guessing that this must be an even more complicated concept than we are aware of. (Scott Adams had something to say about that ...)

Comment: Re:Seems reasonable (Score 2) 53 53

I wonder what restrictions the FAA put on these insurance companies ... like what sort of training do their pilots require?

I imagine they didn't just leave it up to the insurance company, but probably mandated a certain level of training. I know there was talk of requiring a full pilot's license, perhaps a commercial one, for such things.

I don't know if an FAA unmanned aircraft endorsement exists, or they might require a rotorcraft (helicopter) endorsement for your typical quadcopter. Not that all manned aircraft piloting skills apply directly to a model, but certainly a full scale pilot has a leg up on somebody with no experience at all.

And that said, requiring such a certification is way overkill, but it wouldn't surprise me at all.

Whatever the rules are, I'd expect the insurance companies to make sure that whomever operated these was sufficiently skilled to do so competently, either by teaching them to fly the old fashioned way or by providing aircraft that are automated enough that they don't really do much except tell it where to go.

Comment: Re:Seems reasonable (Score 1) 53 53

The FAA doesn't really concern itself with "privacy", which is the primary problem that people have with these so called "drones" -- the FAA's concern is "safety".

And yet they also know that perfect safety is a pipe dream, and so they try to find a balance between safety and utility, and if they err, they try to err on the side of safety. And in the case of unmanned aircraft, they have erred *massively* on the side of safety so far.

The safety concerns of this are very small, and so there's really no reason for them not to do this, and I'm glad they're giving the permits -- it shows that they are finally relaxing their grip somewhat.

Now, if they had not permitted this, then the insurance company's other options are --

-- ladders (probably more dangerous than the R/C aircraft)
-- cameras on a long stick (probably works well enough for one story buildings, maybe not taller ones)
-- manned aircraft (expensive, probably more dangerous than the R/C aircraft)
-- camera on a kite (as dangerous as the R/C aircraft, often not practical, and the FCC may prohibit this as well)

Comment: Re:Pointing out the stark, bleeding obvious... (Score 1) 247 247

Batteries aren't really cost effective for storing the amount of energy that we'd need to power the electrical grid from sunset to sunrise.

That said, even if we we ignore the possibility of storing energy or transporting it long distances to handle the moving (east to west) peak sunlight hours ... even if we can can only get half of our energy from the sun, that's still half of our energy that we didn't have to burn fossil fuels for.

We don't need batteries for that to be a false dilemma.

Comment: Re:APD doesn't have the authority to do this ... (Score 1) 46 46

Turns out I was wrong here -- the ordinance does already exist :

13-1-1 - DEFINITIONS. ...
(6) AIRCRAFT means a device that is used or intended to be used for flight in the air.

13-1-11 - CERTIFICATION REQUIRED.
(A) This section does not apply to a person properly assigned to operate an aircraft by military authority.
(B) A person may not operate an aircraft in or over the corporate limits of the city unless:
(1)the person has an airman's certificate issued by the Federal Aviation Administration; and
(2)the aircraft the person is operating has received a certificate of air worthiness from the Federal Aviation Administration.
(C)The operator of an aircraft in the corporate limits of the city shall deliver the operator's airman's certificate and the aircraft's certificate of air worthiness to a police officer or airport official on demand.
Source: 2003 Code Section 13-1-4; 1992 Code Section 17-2-4; Ord. 040729-16.

Of course, that ordinance is so vague that it effectively bans all hobbyist R/C airplanes in the city -- including at the two R/C club fields in town -- all the time, not just just during SXSW. It also bans paper airplanes. And kites. And frisbees too. (Letting your bird fly is OK, however, as birds are not devices.)

And it's been this way since at least 2003, though I don't think anybody really thought that it might apply to all of these things until now. Selective enforcement of the laws is rarely a good thing, and now that the cat is out of the bag it'll be interesting to see how this will be selectively enforced after SXSW is over.

Comment: Re:APD doesn't have the authority to do this ... (Score 1) 46 46

423.003 likely did not apply there, because that's not really private property and I doubt the intent was to "conduct surveillance". (The term has a specific legal definition -- "Observation and collection of data to provide evidence for a purpose" -- and I'm not sure Texas has a more specific definition. Is looking for a cool picture "providing evidence"?)

Also note that APD's supposed ban says nothing of cameras, only of "drones". (No, contrary to what the media may tell us, R/C aircraft do not all have cameras or missiles.)

And of course "Reckless conduct" is vague enough that they could probably apply it to anything.

What probably did apply there is this NOTAM from the FAA which prohibits flying under 3000' over stadiums shortly before, during and shortly after events. State police don't normally enforce FAA regulations, but it's certainly possible.

That won't apply to the city of Austin during SXSW, and 423.003 probably won't apply to public spaces, but certainly, APD could try "reckless conduct" -- and even if the charges were eventually dropped because they don't really apply, that doesn't beat the ride downtown.

Comment: APD doesn't have the authority to do this ... (Score 1) 46 46

The city council could pass an ordinance, which APD could then enforce, but as it stands, unless the ordinance has been passed recently, no such ordinance exists.

That said, the parks and recreation department did recently decide to ban all R/C airplanes in all parks (page 11), with the only current exceptions being the HCAM and ARCA fields. That said, those rules only apply to parks -- if you fly from a street, or your driveway or a school or something, they don't apply.

(Oddly enough, I don't think anybody even knew about the ban. Based on the response I got from the city, I was the only person city wide to comment on it (and no, I was not in favor.)

In any event, if somebody is flying over a crowd, they might be able to find a law to charge somebody with. But if not over people and not over a park, not in a dangerous manner ... I don't see where they'd have any say in the matter.

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