* * * The Minimal Ammeter? * * *
- Thread starter safe
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safe said:Whatever happened to the spirit of "Boldly Going Where No Man Has Gone Before?"
The whole point of a discussion thread it to think and exchange the possibilities that those thoughts might suggest. There are no "sacred" technologies... all things pass away with time as they are replaced with something else or if they are really good sometimes they stay the same. It's called "evolution". Only that which "fits in well" (is useful) survives.
Anyway... I like that idea of the blinking light. When you are using very little current it blinks very infrequently, but as the current draw increases it speeds up to the point that it's just a bright light. With no current it's off completely. Now that's what you call "good thinking". Who the heck is this "new guy"? He seems pretty smart. 8)
How about using a radar detector style display?
I don't understand why you naysayers are saying nay? Analog gauges require taking one's eyes off the road and actually looking at them, so you can't always know what they're showing. A digital one is even worse because you have to actually read the numbers it's displaying.
This light would make an amp meter who's reading needs not be read, or even looked at directly. There's no need to take one's eyes off the road at all to use it, your peripheral vision should be able to take care of that. Adding this on a DB would address it's only true weakness - you have to read it.
Variable blinking seems like a good idea for this because peripheral vision is better at seeing movement, I can see this combined with a LED that gradually shifts from say green to red, like on my battery charger. Or maybe three colours if it's doable?
This light would make an amp meter who's reading needs not be read, or even looked at directly. There's no need to take one's eyes off the road at all to use it, your peripheral vision should be able to take care of that. Adding this on a DB would address it's only true weakness - you have to read it.
Variable blinking seems like a good idea for this because peripheral vision is better at seeing movement, I can see this combined with a LED that gradually shifts from say green to red, like on my battery charger. Or maybe three colours if it's doable?
xyster
10 MW
Well said, except I can read my large analog meters from my peripheral vision so long as it's daylight.
safe
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Matt Gruber said:
Gears are still a necessity.With my new controller all of sudden my range drops in half if I use my high gear set. So I've actually been going BACK to my lower gearset in order to get some fuel economy. Basically now it only takes one or two decent sized hills with the tall gear to drain large amounts of the battery and while I can "pull" my way up it with lot's of amps and torque the losses in energy are just sad.
I'm actually thinking of going to either a lower limit controller (30 amp) or (better) to get that "Boost Control" circuit made so that I can decide:
"Hmmmmm.... do I want power or range today?"
xyster
10 MW
You have a throttle; I bet that throttle has more positions than just "insane". It makes for a decent current limiter if you can learn how to twist it just part way.
Short of teaching an old Safe new tricks, that 30 ah NiMH pack you're pondering should be your ticket to ride fast and far.
safe
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xyster said:You have a throttle; I bet that throttle has more positions than just "insane". It makes for a decent current limiter if you can learn how to twist it just part way.
But hills don't respect your desire to save energy so if your gearing is high (for top speed) the energy demands are high. If you use the low gearing then the hill climbing is efficient (slower, but in the "powerband") but you lose the top end. Right now I have a 200% gearing "spread", but the 8 speed will increase that to 300% so the newer ones will be able to do both.
It all comes down to "compromise" and that usually means (for now) picking one "riding mode" or the other before you ride...
PS: bobmcree I will answer yours later... good post.
TylerDurden
100 GW
LEDs, Analog guages, DVMs... whatever.
All ya really need is wire and a pair of alligator clips...
Why do ya think they call em TESTicles??
All ya really need is wire and a pair of alligator clips...
Why do ya think they call em TESTicles??
xyster
10 MW
I forgot that half your gears can't be accessed without physically moving the chain.
Like at Abu Ghraib? Somehow I don't think it tesTICKLED, more like testorturcled.
Matt Gruber said:
aaaaxe-celent!
I got a half dozen of these DVM's for twenty bucks precisely for this purpose, instrumentation on my ebike. 'Calibeur' moulded into the probes is the only name on it anywhere, if anyone has any info on what the lone internal pot adjust does. It may not be the simplest, but by far cheaper then anything you can build yourself. I mean you can't even buy replacement test leads at that price. :?
Care to elaborate on the calibration procedure. The max range on this meter is 10A, so a parallel shunt would have to be 1/10th or is it 1/9th the resistance of the existing shunt to give a 100A range?
The A/D is a black blob mounted in behind the LCD. It's looking good that I may be able to cut back the PCB to eliminate the big rotary knob. The goal is to wind up with dedicated single range ammeters & ESV that wouldn't be much bigger than just the readout mounted in a suitably sized enclosure.
Excellent tip & recommend everyone do this. It's basic metering that should be standard & at this kind of price point I fail to understand why it isn't.
Ypedal
100 TW
Matt Gruber said:
Matt.. get a grip on reality.
It's posts like this that prevent most new members from posting at all in the first place. Risk of ridicule.
I do " Technical Support " for a living.. been at it 10 years. What seems simple and crystal clear to you.. is not understood the same way by everyone else.. i have to remind myself of this every day as i'm asked the same questions.. over.. and over.. and over..
These questions prompt the people who know aka: Bob.. to explain things indetail, this helps everyone.. including myself.. I admire that.
If you can't say something nice.. well..
i gave this idea a little more thought and came up with some refinements. what we want is a display that conveys as much information as possible as quickly as possible without requiring too much attention. people seem to be in agreement that changing color and blink rate are good easily perceived means to convey information.
there are LEDs for displays made by Nichia and others that have individual red, green, and blue devices with driver chips all in the same LED package. One of those devices could be used, and the combination of color and blink rate could instantly convey whether conditions were in one of several states by the color and quantitative display of a variable value appropriate to the displayed state could be achieved by varying the blink rate.
these displays can produce an almost complete range of color through the entire visible spectrum, so it would be possible to go from blue to green to yellow to orange to red to violet over the range of values to be displayed, and the blink rate could be used to signify additional information relevant to the state indicated by the color. as an indication, color alternating between red and violet, fast blink, means imminent lithium meltdown, get off and run!!
It is easy to see how the combination of color and blink rate could be used to convey a lot of information efficiently and quickly. LED devices meant for daylight displays are available that could make the indicator visible in direct sun.
personally i find my DrainBrain quite adequate. but it is an interesting problem to come up with efficient displays that do not distract the driver.
-bob
there are LEDs for displays made by Nichia and others that have individual red, green, and blue devices with driver chips all in the same LED package. One of those devices could be used, and the combination of color and blink rate could instantly convey whether conditions were in one of several states by the color and quantitative display of a variable value appropriate to the displayed state could be achieved by varying the blink rate.
these displays can produce an almost complete range of color through the entire visible spectrum, so it would be possible to go from blue to green to yellow to orange to red to violet over the range of values to be displayed, and the blink rate could be used to signify additional information relevant to the state indicated by the color. as an indication, color alternating between red and violet, fast blink, means imminent lithium meltdown, get off and run!!
It is easy to see how the combination of color and blink rate could be used to convey a lot of information efficiently and quickly. LED devices meant for daylight displays are available that could make the indicator visible in direct sun.
personally i find my DrainBrain quite adequate. but it is an interesting problem to come up with efficient displays that do not distract the driver.
-bob
Ypedal
100 TW
Regarding the meter question.
I absolutely LOVE my Drainbrain.
Night riding.. no problem.. get the Back-lit version ! hehe..
Taking my eyes off the road, well, honestly, i don't find this to be a problem as long as you have the meter mounted correctly. I can look at the meter.. and have my eyes back on the road in aprox 1 to 2 seconds.
The blinking LED is a cool idea however. that i like.
The Needle meters, personally , i find them a tad too " Old fashion " to be on a high-tech E-bike !
I absolutely LOVE my Drainbrain.
Night riding.. no problem.. get the Back-lit version ! hehe..
Taking my eyes off the road, well, honestly, i don't find this to be a problem as long as you have the meter mounted correctly. I can look at the meter.. and have my eyes back on the road in aprox 1 to 2 seconds.
The blinking LED is a cool idea however. that i like.
The Needle meters, personally , i find them a tad too " Old fashion " to be on a high-tech E-bike !
Matt Gruber
1 MW
Toorbough ULL-Zeveigh said:
Matt Gruber
1 MW
i NOW return this thread to safe.
I'll write a new page on my site called DVM tips & tricks when i get time.
Safe, since LED throttles are quite popular, u could experiment. The LED lights up on high amps, and i think that is what u want. They actually read volts, but under high drain, v sags, and the LED lights up. Quite a helpful device, once u learn how it works! Standard on all Razors and many others.
I'll write a new page on my site called DVM tips & tricks when i get time.
Safe, since LED throttles are quite popular, u could experiment. The LED lights up on high amps, and i think that is what u want. They actually read volts, but under high drain, v sags, and the LED lights up. Quite a helpful device, once u learn how it works! Standard on all Razors and many others.
Reid Welch
1 MW
I enjoy the backlit Drainbrain with cyclo functions.
Lots to read. But as Mathurin noted, you have to read.
As Xyster noted, an analog ammeter needle can be read almost peripherally
---I should have one of them on my bike as a reminder to apply throttle judiciously---because it's -instantaneous, and right there.
Then again, as Matt notes: once you know what your bike does under all the encountered conditions, you don't really need an ammeter at all.
But I like the Drainbrain for its many indications, such as Wh/mile and miles traveled and Ah indications, etc. It's neat and inclusive, but it's not a flash to read. A needle is, and if lit, a needle can be seen same at night as in daylight. That's won't obtain with an LED system: if an led indicator is made bright enough for daylight, it will be totally obnoxious at night.
(who rides at night? well, I do)
Hooray for diversity. We're all fowls waddling our own ways. c
The other guy is always a relative gimp,
I will now note,
and duck out;
quack!
Lots to read. But as Mathurin noted, you have to read.
As Xyster noted, an analog ammeter needle can be read almost peripherally
---I should have one of them on my bike as a reminder to apply throttle judiciously---because it's -instantaneous, and right there.
Then again, as Matt notes: once you know what your bike does under all the encountered conditions, you don't really need an ammeter at all.
But I like the Drainbrain for its many indications, such as Wh/mile and miles traveled and Ah indications, etc. It's neat and inclusive, but it's not a flash to read. A needle is, and if lit, a needle can be seen same at night as in daylight. That's won't obtain with an LED system: if an led indicator is made bright enough for daylight, it will be totally obnoxious at night.
(who rides at night? well, I do)
Hooray for diversity. We're all fowls waddling our own ways. c
The other guy is always a relative gimp,
I will now note,
and duck out;
quack!
safe
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bobmcree said:
I was thinking about his a little more and this is what I've come up with. Current and voltage in a wire always have "inefficiencies". One form of "inefficienciy" is heat... the heat that builds up in a wire if the resistance is high can actually be felt. (like my previous wiring used to do
) The other form of energy loss is the magnetic field that gets created using the "right hand rule" surrounding the wire and this forms the basis of the Hall Effects Sensor. Normally the sensor only covers a very small fraction of this magnetic field, but such a field is not unlike the field that actually makes the motor work. An electric motor is really just an electrical "inefficiency" caused by current flowing through wires wrapped into coils and creating magnetism. Electrical motor power is really just a magnetic "leak". :? So one must ask:"If I were to wrap an ENTIRE FOOT long length of the wire going from the battery to the motor with a coil isn't that going to create a pretty large 'trickle' current in a Hall Effects manner?"
Rather than seeking a "leak" to exploit in the current itself there is already a lot of magnetism flying around as it is, so that seems the better area to be investigating.
What about something like a "coaxial cable"?Aren't those wires designed with the idea of "trapping" the magnetism and if so, couldn't you just replace a foot of wire with "coaxial cable" and then just string wires off of the shielding layer to an LED?
Or does the coil around the wires need to be really a "coil" and not "braided"?
Are there wires that have "coils" built into them (embedded) that would be offered in a 10 gauge core size? Then you just buy a foot of that and wire it in...
While current flowing through a wire does produce a magnetic field around it, you can't get any energy from it unless it's an alternating field.
I suppose if you had a brushless motor and put one of the 3 phase wires through a torroid wrapped with enough turns of wire, you could get enough voltage to light up an LED. In this case, the torroid and windings are acting like a transformer.
A hall sensor can measure the magnetic field, but it does not extract any energy from it. The energy must be supplied to the hall sensor by another source.
I suppose if you had a brushless motor and put one of the 3 phase wires through a torroid wrapped with enough turns of wire, you could get enough voltage to light up an LED. In this case, the torroid and windings are acting like a transformer.
A hall sensor can measure the magnetic field, but it does not extract any energy from it. The energy must be supplied to the hall sensor by another source.
safe
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fechter said:
That makes no sense!Electromagnetism means that for every current there is a corresponding magnetic field. If there is a coil wrapped around the wire then the magnetic energy given off by the wire should induce another current in the coil. The longer the coil the higher the electrical force created in the coil wire.
How can it be anything other than this?
I seem to recall someone previously in this thread suggesting the use of an inductive clamp which seems to be what you are describing.
Toorbough ULL-Zeveigh said:
With a steady (DC) current flowing through a wire, the magnetic field is static, just like a permanent magnet. If you put a wire up against a permanent magnet, you won't get any energy from it unless you're moving the wire. Same thing here. You could put a compass needle near the wire and measure the current, but changing direction might affect your reading.
You can get energy from a change in the magnetic field. If you have a PWM controller, you could get some energy from the wire when you are at less than full throttle. Hmm.... That might work.
But once you hit full throttle and the PWM stops switching, your indication would drop to zero.
The cheapest and easiest way to make a LED light up at a certain current (DC) would be to use a shunt and an amplifier. A hall sensor might be easier, but more expensive.
One more idea: If you took a relay and removed all the windings and replaced them with a foot or so of really heavy wire (minimal resistance), the relay will pull in when you exceed a certain current. The pull-in point could be adjusted by changing the number of turns or the spring tension.
Then it's easy to hook up a LED so it lights up when the relay closes.
I have no idea how many turns it would take for a given current. You would need to experiment.
Got relays?
You can get energy from a change in the magnetic field. If you have a PWM controller, you could get some energy from the wire when you are at less than full throttle. Hmm.... That might work.
But once you hit full throttle and the PWM stops switching, your indication would drop to zero.
The cheapest and easiest way to make a LED light up at a certain current (DC) would be to use a shunt and an amplifier. A hall sensor might be easier, but more expensive.
One more idea: If you took a relay and removed all the windings and replaced them with a foot or so of really heavy wire (minimal resistance), the relay will pull in when you exceed a certain current. The pull-in point could be adjusted by changing the number of turns or the spring tension.
Then it's easy to hook up a LED so it lights up when the relay closes.
I have no idea how many turns it would take for a given current. You would need to experiment.
Got relays?
safe
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It might be that you would need to have such a large length of wire to get any decent level of current that it makes the whole idea impractical. I know that the Hall Effects Sensors can only produce a trivial amount of power from them that then need to be amplified to do anything practical. But (like with all forms of "recycling") if you could "recycle" all the wasted energy going into the atmosphere due to the magnetic fields flying off of your wires and concentrate that "waste" and turn it into "light" then you gain something out of nothing.
I like to be "cheap".... I mean "efficient"... :wink:
I like to be "cheap".... I mean "efficient"... :wink:
Toorbough ULL-Zeveigh said:
I don't see why an inductive pickup wouldn't work on a brushless motor if it was installed on one of the phase wires where it's AC. At low speeds, it might read weird.
On the wire from the battery to the controller, it's DC, so an inductive pickup won't work. They do make clamp-on hall effect units that work with DC, but they're usually pretty expensive. I have one made by Fluke.
safe
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http://en.wikipedia.org/wiki/Hall_effect
Hall effect devices when appropriately packaged are immune to dust, dirt, mud, and water. These characteristics make Hall effect devices better for position sensing than alternative means such as optical and electromechanical sensing
When electrons flow through a conductor, a magnetic field is produced. Thus, it is possible to create a non-contacting current sensor. The device has three terminals. A sensor voltage is applied across two terminals and the third provides a voltage proportional to the current being sensed. This has several advantages; no additional resistance (a shunt, required for the most common current sensing method) need be inserted in the primary circuit. Also, the voltage present on the line to be sensed is not transmitted to the sensor, which enhances the safety of measuring equipment.
So if a Hall Effects Sensor can apply its own current it can "sense" the magnetic field strength... but it's not "using" the magnetic field as a "source" of energy, but instead as a "calibration scheme" for it's own supplied energy.
Hmmmm...
So you really only have the potential of current when the magnetic field changes... which makes it more of a "triggering" concept than a "flow" concept. It's the first "derivative" of current (dx/dt) that can produce an external current flow... okay, that makes sense... so you really can't run an LED directly from the magnetic field...
Hall effect devices when appropriately packaged are immune to dust, dirt, mud, and water. These characteristics make Hall effect devices better for position sensing than alternative means such as optical and electromechanical sensing
When electrons flow through a conductor, a magnetic field is produced. Thus, it is possible to create a non-contacting current sensor. The device has three terminals. A sensor voltage is applied across two terminals and the third provides a voltage proportional to the current being sensed. This has several advantages; no additional resistance (a shunt, required for the most common current sensing method) need be inserted in the primary circuit. Also, the voltage present on the line to be sensed is not transmitted to the sensor, which enhances the safety of measuring equipment.
So if a Hall Effects Sensor can apply its own current it can "sense" the magnetic field strength... but it's not "using" the magnetic field as a "source" of energy, but instead as a "calibration scheme" for it's own supplied energy.
Hmmmm...So you really only have the potential of current when the magnetic field changes... which makes it more of a "triggering" concept than a "flow" concept. It's the first "derivative" of current (dx/dt) that can produce an external current flow... okay, that makes sense... so you really can't run an LED directly from the magnetic field...
fechter said:
I thought I remember seeing an DC range on those things. So it is Hall & not inductive. Thanx for that info. I'm just curious about the lower limits that they can work at & how the accuracy is affected as you approach those limits, like you said, start to read weird.
It's simply the idea of not having any voltage dropped in a shunt that appeals to me, & that it can't burn out from overcurrent. Thanx again for your help.
