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Old 01-07-2017, 07:28 PM   #41 (permalink)
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Originally Posted by Thunder Fighter View Post
As someone who has flown with mAh telemetry for several years with heli's I can say it is the most reliable method available.

The issues you bring up are easily solved. I have a voltage alarm that activates when I first plug in the pack so I always know my packs are above 95% when I put them in the heli, I also always have a low voltage alarm set so if by some case something goes wrong with the mAh measurement I have a backup that should stop me damaging my packs.

For the multiple size packs I can setup a switch to take account of the pack capacity I put into the heli but now with LUA and the Jeti and some great work by Teros on his RC-Thoughts web page you can automate it so the capacity limit is set by the RFid tag attached to the pack that updates the application on the Tx via telemetry. The Vcontrol also has the capability to do this in an automated way with RFid tags.

You can tweak the capacity measurement to bring the packs down at a consistent level every time and adjust over time if you have packs coming down lower as they age. With the RFid method you can burn a new tag when required at a lower capacity so it is all automated.

With all of this it is a pretty foolproof system, I always leave a little in hand and alarm at 70% used so by the time I land I am well within 25% remaining and this little buffer takes into account any issues with small capacity differences between packs and temperature over the range I fly in.

Voltage measurement in flight might be fine for sports or scale pilots where the load is fairly consistent but it just doesn't work for flying 3D flight and especially when you fly very different headspeeds. Even with averaging of the voltage, if I set my alarm where needed when flying in my fastest head speed and throwing around the heli the voltage drops are large, so will need to be down in the low 3v range, then if I take my lowest head speed which cuts the current draw and load (i.e. voltage drop) on the pack down by 75% (even doing 3d) the cutoff will be way too low.

I could say the same thing about the voltage method in that this might work fine for someone who always flys the same head speed and style in a flight, but I can tell you that when flying very different head speeds (e.g. 1350/1650/1900rpm) and styles of flight within one flight the mAh method is by far the most foolproof and workable solution.

//Dennis.


Very well said!
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Old 01-07-2017, 07:29 PM   #42 (permalink)
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I'm never over discharged a battery since I started using mah timers and they have worked very reliably and consistently.

+1000
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Old 01-07-2017, 07:31 PM   #43 (permalink)
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With the capacity method it doesn't matter how I fly, or what headspeed I use so long as I start with a full pack, my resting voltage and capacity remaining in the pack is very consistent at the end of the flight. And it still doesn't stop me using specific voltage alarms to catch a bad cell or other issues.



//Dennis.

That says it all!

Carlos
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Old 01-07-2017, 07:51 PM   #44 (permalink)
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I agree 100% I fly mAh used on all my helicopters. One thing I haven't read about is OpenTX on the FrSky radios which next to the Jeti is probably the best radio to use with telemetry, definitely much cheaper.
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Old 01-08-2017, 07:26 AM   #45 (permalink)
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I actually combine a few things. Most critical to me is fully charged battery so I have the warning if not fully charged while heli gets initialized.
Second I have a mAh announcement every 500 mAh consumed. That helps me flying different size packs to know when to land. After 2500 mAh I am told the value 3 times so I cannot miss it.
In addition - I have low voltage alarm for BEC and main battery to help identifying batteries that become weak under load and I use temperature alarms to avoid overheating the ESC or BEC. Easy setup using either JLog or TelMe and pulling the data from my ESC directly.

So mainly I fly based on mAh consumed while I do get warned in case of other issues so I can respond to it. My batteries come down always the same since I started it and I am very happy with telemetry. Specifically because I get everything needed from one single unit.
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Old 01-08-2017, 08:18 AM   #46 (permalink)
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Originally Posted by mkovalcson View Post
What I see is a LOT of futzing around with Voltage which seems like a real waste of time.

I'm never over discharged a battery since I started using mah timers and they have worked very reliably and consistently.

But if you guys know better, have at it. I have nothing more to add.
Very well said. My experience has been the same. The beauty of a PL8 charger is when I put my flight battery back on the charger it immediately tells me at what capacity it is at. In this way I know that my MAH capacity telemetry is doing its job reliably.

There seems to be a lot of theoretical talk going on about how voltage telemetry can be made to be better with simple circuits, filters and such.
Well theoretical can be just that.
Meanwhile, the rest of us are enjoying reliable flight battery discharge, simply and efficiently.
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Old 01-08-2017, 12:25 PM   #47 (permalink)
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you guys crack me up, so much emotion over discharge tracking... lol
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Old 01-08-2017, 01:11 PM   #48 (permalink)
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you guys crack me up, so much emotion over discharge tracking... lol
It's cold.
We have to have something to argue about.
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Old 01-08-2017, 02:01 PM   #49 (permalink)
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you guys crack me up, so much emotion over discharge tracking... lol
Some people get really anal about their batteries. There’s a guy looking for people to try out his battery tracking app. Way too much trouble for me, I really don’t care how many flights I have on a battery when it goes bad I’ll get another one doesn’t matter if it’s 200 flights or 500. Something I just thought of I should do is date when I got the pack so I know how long it lasted which I haven’t done on any packs.
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Old 01-08-2017, 02:20 PM   #50 (permalink)
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I'm never over discharged a battery since I started using mah timers and they have worked very reliably and consistently.
this has been my experience too.
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Old 01-08-2017, 02:31 PM   #51 (permalink)
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this has been my experience too.
Mine too, this is because I'm human and makes mistakes. My setup tells me if the battery is not charged when I connect it. And it counts the amps as I fly, in practice this works. I also don't select neither model or battery when flying. It's all automatic and very little room for error. This wouldn't be possible without telemetry.
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Old 01-08-2017, 05:22 PM   #52 (permalink)
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OP-

Ironically, the nonsense in this thread illustrates my point- you have to know what it is that you are after, and what solution will get you there. Here, you have adults who are looking at actual logged data from a 3D flight, where the battery was crushed in collective punches (first punch in the flight pulled a freshly-charged pack down to 3.2v/cell). And with that is overlay filter data for both a ‘bad’ sensor design, and a better one. And instead of looking that the better sensor output, and asking ‘how does this not fail like I expect it should,’ they proclaim it ‘theoretical.’ And, in the process, they don’t learn about how the filter works, and they remain stuck in a mentality that doesn’t resolve problems inherent to a solution they prefer.

I posted that data not to convince people their approach is wrong, but to show that if you understand the system you are monitoring, and you understand your telemetry hardware, you stand a better chance to use the data in a productive way. Otherwise, it can take you in a bad direction.

Here is another example- Im sure the fanboys will have another tantrum about it- but again- this is actual raw data from an off-the-shelf system many of us fly (FrSky Taranis Plus, X4RSB receiver, native telemetry). No hardware or software filtering here- the DSO data shown is measured at the A2 input terminal of the receiver. TX filtering is disabled. The TX is calibrated to read within 0.1v from 3 to 20v for this channel input.

In this, a controlled voltage was fed into the voltage monitoring input of the receiver. This voltage was carefully controlled- where it was set to 6.3v, with brief dips to 3.68v (near brownout for most receivers and servos). Those dips were about 3ms in length, the same as you see with a typical servo reversal. In 4 seconds of logging, 100 dip events were generated, and 4 were caught. Except, they were averaged, and the read value (as you can see in the raw log) was 5.6v, not the actual value of 3.68v. So, after the flight, you look at your telemetry- and you see only 4 events, and worst case is a dip to 5.6v. Bus is fine! Except, it isn’t- it is a disaster. Same holds for something like servo current meters, peak motor current, etc. So you have to shake off the sheep mentality that is so common in this hobby, and ask questions. There are people here and elsewhere who actually measure data before they make conclusions, and are happy to help people who are looking to learn. Some of us are degreed EEs or AEs (or both…).
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Old 01-08-2017, 06:31 PM   #53 (permalink)
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OP-

Ironically, the nonsense in this thread illustrates my point- you have to know what it is that you are after, and what solution will get you there. Here, you have adults who are looking at actual logged data from a 3D flight, where the battery was crushed in collective punches (first punch in the flight pulled a freshly-charged pack down to 3.2v/cell). And with that is overlay filter data for both a ‘bad’ sensor design, and a better one. And instead of looking that the better sensor output, and asking ‘how does this not fail like I expect it should,’ they proclaim it ‘theoretical.’ And, in the process, they don’t learn about how the filter works, and they remain stuck in a mentality that doesn’t resolve problems inherent to a solution they prefer.

I posted that data not to convince people their approach is wrong, but to show that if you understand the system you are monitoring, and you understand your telemetry hardware, you stand a better chance to use the data in a productive way. Otherwise, it can take you in a bad direction.

Here is another example- Im sure the fanboys will have another tantrum about it- but again- this is actual raw data from an off-the-shelf system many of us fly (FrSky Taranis Plus, X4RSB receiver, native telemetry). No hardware or software filtering here- the DSO data shown is measured at the A2 input terminal of the receiver. TX filtering is disabled. The TX is calibrated to read within 0.1v from 3 to 20v for this channel input.

In this, a controlled voltage was fed into the voltage monitoring input of the receiver. This voltage was carefully controlled- where it was set to 6.3v, with brief dips to 3.68v (near brownout for most receivers and servos). Those dips were about 3ms in length, the same as you see with a typical servo reversal. In 4 seconds of logging, 100 dip events were generated, and 4 were caught. Except, they were averaged, and the read value (as you can see in the raw log) was 5.6v, not the actual value of 3.68v. So, after the flight, you look at your telemetry- and you see only 4 events, and worst case is a dip to 5.6v. Bus is fine! Except, it isn’t- it is a disaster. Same holds for something like servo current meters, peak motor current, etc. So you have to shake off the sheep mentality that is so common in this hobby, and ask questions. There are people here and elsewhere who actually measure data before they make conclusions, and are happy to help people who are looking to learn. Some of us are degreed EEs or AEs (or both…).
Extrapilot, some that have answered you are EE's. (MKovalcson for one)

Please don't post another graph. Post YOUR flight video with your telemetry system using voltage to track your battery discharge. Post pictures of YOUR system and how it is configured. Post detailed PICTURES of YOUR setup.

I would be interested in this.
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