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01-14-2009 12:43 PM  9 years agoPost 1
fenderstrat

rrProfessor

Aston,Pa

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I see a lot of the lipo alarms go from pack voltage,which is not the ideal way to measure,some are going by cell V,Why cant a company make a lipo monitor that measures MAH used,and triggers the alarm when a preset MAH are reached.seems a more acurate way of measuring as V can vary from flight to flight but say for example if you are using a 11.1V 2200mah battery set it for 1600mah.this would give you a good 30 sec to land your heli(you could set it lower if you want)and still be under 1760 mah.

V can vary depending on the battery and how you fly but mah is mah,once you hit a certain number you are done,seems like a better idea to me

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01-14-2009 02:59 PM  9 years agoPost 2
tryan02

rrProfessor

Canton, Missouri

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current maH is measured in series. Therefore I ass-u-me you would have to splice one of the current wires to add such a circuit without developing a algorithmic device requiring some type of microprocessor technology making it somewhat large and heavier than a voltmeter only to guesstimate actual usage. Install would have to be much like the BCPP fuse mod remember that adding a fuse inline with the battery positive lead to save the 3 & 1 in a crash.

Sometimes people get caught up safeguarding an inferior product from failure than actually just demanding a better product.

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01-14-2009 03:54 PM  9 years agoPost 3
Melnic

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Columbia, MD,USA

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Yup, you'd have to measure current and voltage to get mAh.
Wonder if the Eagle Tree is headed in that direction or not.
I have 2 lipo alarms. Both off Ebay. One measures voltage across each cell as well as a total. It hooks up to the balance plug. I used it a couple times w/ the 450. The volt meter is not as accurate as my regular DMM. It has an error of about .05 volts. But it is better than not knowing at all.

Ok, what does a Lipo alarm have to do with battery quality? Every flight is different and even using a timer is not 100% reliable. My esc's will reduce power on a low voltage. Who knows how accurate the ESC's voltage detection is?

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01-14-2009 08:18 PM  9 years agoPost 4
tryan02

rrProfessor

Canton, Missouri

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add such a circuit without developing a algorithmic device requiring some type of microprocessor technology making it somewhat large and heavier than a voltmeter only to guesstimate actual usage
What I meant by this was that some of our cars nowdadays tell us when to change our oil by calculating its duty cycle. Run time, miles, temperature whatever parameters the engineer sets them too. The same could be done with a voltmeter for our helis but it would require a set of parameters to do so and those parameters being calculated by a microprocessor running an algorithm of the parameters. Just like the cars do using temps, volt drop, and run time or maybe even IR values.

I think it could be done fender but like I said its still calculated and I wouldn't trust it change it at 7min or 3000miles.

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01-14-2009 10:56 PM  9 years agoPost 5
fenderstrat

rrProfessor

Aston,Pa

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but as already said the EAGLETREE data logger tracks MAH used,rather accurately from what I can tell,so why not trim it down as in lose the airspeed indicator,altimiter, rpm, and temp sensor stuff, ect ect and just have it measure MAH,make it programmable and there we have it

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01-14-2009 11:20 PM  9 years agoPost 6
tryan02

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Canton, Missouri

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great now you got me studying something I care nothing about.

OK thanks fender for showing me that someone has already done what I was talking about. Dang expensive though I see they also now have a power panel LCD display that does almost what you just asked for but at a very high price.

http://www.eagletreesystems.com/MicroPower/micro.htm

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01-15-2009 12:03 AM  9 years agoPost 7
fenderstrat

rrProfessor

Aston,Pa

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but if you trim all the unnecessary functions and make it programmable in 25 or 50 mah increments(like an esc,combinations of beeps)) or use a pc link and program it(like a CC bec) on a computer(eliminate the power panel)just have a series of led's and have it pulse the tail or main motor when you get to target MAH,I cant see how it would cost a lot as the DATALOGGER3 isn't too expensive and it tells you all sorts of stuff and has many features

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01-15-2009 12:23 AM  9 years agoPost 8
tryan02

rrProfessor

Canton, Missouri

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Agreed!
I see what you mean I found the $70 for the data logger ridiculous and the $40 power panel even worse.

Maybe you can speak with eagle-tree and as a battery Rep and discuss with them what you are looking for? With that last voltwatch topic we had it looks like there is interest in such a device. But how will they market it? as a $100 datalogger with onboard battery watchdog or a $30 onboard battery watchdog they already have the hardware there so getting them to add a product to there portfolio may not be cost effective. Cause at the end of the day its all about the benjamin's.

For me its just not worth $70 to save a $50 battery.
personal preference thing.

but a $300 battery well thats just different.

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01-15-2009 01:14 AM  9 years agoPost 9
fenderstrat

rrProfessor

Aston,Pa

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For me its just not worth $70 to save a $50 battery.
but think in the LONG term,how many batts do you have??

right now I have 9 that are in current rotation

and if the datalogger3 is 70 bucks with all those features,I would think it could be at least half if it only has one function

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01-15-2009 01:22 AM  9 years agoPost 10
tryan02

rrProfessor

Canton, Missouri

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Your right it could work great for that niche.

had 4packs year old FMA 18C just got puffy so to the raptor it went for the RX pack. You figured that out for the Knight yet? Anyway the 3 packs I have left 1 align pack and 2PPRC are Ok for what I need and I know a battery rep that sells some damn good packs If I get a $50 bill burnin a hole in my pocket I'll pick up another one. But remember I am lovin the nitro. A quick flyby will tell ya everything you need to know!!!

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01-15-2009 01:29 AM  9 years agoPost 11
Gregor99

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Western Wa

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I'm all for gadgetry and overthinking a solution to a problem. So don't get me wrong when I say this, but don't you completely avoid this issue with the use of a timer and keeping the flight time under the 80% rule?

I do think you are onto something with the stripped down Eagle tree solution. But what happens when you swap between different sized packs. You'd have to change the mah setting on the device. Would that be via dip switches, jumpers, or a pc connection. Regardless of method, I'm know that I'm likely to forget more than once.

You could argue that changing the timer settings on your radio requires you to make a change when use different packs. But on the DX7 its fairly easy and straightforward.

I think lipo alarms are great. But thier best application is for heli owners that don't have timers on thier Tx and/or a MAH reading on thier charger. For the rest of us, this issue has been for the part solved a long time ago. Except the rare occassion I pick up drained pack thinking its fully charged But in that case, the mah meter wouldn't help, where as the voltage alarm would.

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01-15-2009 01:59 AM  9 years agoPost 12
fenderstrat

rrProfessor

Aston,Pa

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I'm all for gadgetry and overthinking a solution to a problem. So don't get me wrong when I say this, but don't you completely avoid this issue with the use of a timer and keeping the flight time under the 80% rule?
that works great as long as you fly the same way every time,but suppose one of your flights is a little more aggessive,this would eliminate all guess work and allow you to get the full flight time out of ANY battery no matter how you fly

have you ever been testing and landed and took off a few times,it uses different ammounts of juice,this way you could test till the lipo alarm triggered and you would not have any more flights where you only took say 1200 mah out.that last 400 or so mah could have been enough time to "get the tail just right" instead of swapping batteries

using a timer is still only a rough estimate and is far from an exact science,measuring MAH would be just about EXACT every battery every flight

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01-15-2009 03:55 AM  9 years agoPost 13
Gregor99

rrElite Veteran

Western Wa

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that works great as long as you fly the same way every time,but suppose one of your flights is a little more aggessive
I do fly the same way every time. When I change my flying style, I'll lower my flight times until I can charge the packs and see how many mah I'm consuming. Same thing for changes in the heli that would increase the current draw. Run shorter flights until the consumption can be measured.
allow you to get the full flight time out of ANY battery no matter how you fly
How do would you accomodate a change in pack size? Its common to fly more than one pack size on the same heli. The device would need to be told what pack you are running. I don't see an easy or cheap way to do this.
have you ever been testing and landed and took off a few times,it uses different ammounts of juice,
Yes, that is one scenario where the timer will fail you and more than once I've gone a little too far on the discharge. But I don't end up spending alot time tuning any more so this is not a "key usage scenario", at least for me.
using a timer is still only a rough estimate and is far from an exact science,measuring MAH would be just about EXACT every battery every flight
Agreed, as long it there was an easy way to tell the device the size of the pack. However, I find the lack if precision using the timer method to be sufficient for me. I tend to get fairly consistent discharge results when I stick to the timer and am usally still above 20% remaining. So though it may not be acturate, it is close enough, at least for me.

The other point I'll make is regarding "getting the most out of your packs". You didn't say it and perhaps you weren't thinking of it. But in case you were, my thoughts are this; I treat my packs like the engine in my car. Yes, I do redline my car from time to time, but I keep the oil fresh and don't run to redline every shift.

With my packs I keep them cool and rarely run them past 80%. I try not to push them thier limits very often if at all. For me getting the most out of my packs is more about the number of flights, than the number of minutes. Staying at some vague number, between 70% and 80% capacity helps with that goal, moreso that running them down the exactly 80% every run.

Lastly, an mah gauge won't help you if you accidentally grab discharged pack and go out to fly. A cheap voltage based lipo would cover this scenario better than an expensive mah meter. A good solution would be an alarm that looks at both mah and voltage.

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01-15-2009 04:59 AM  9 years agoPost 14
fenderstrat

rrProfessor

Aston,Pa

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we can go round and round on wether people think they are good or not or who or who doesn't want to use them,that wasn't my point.the point was LOTS of people do use them,so why isn't there one on the market designed the way I had described.i personally dont use one and most likely never will,The timer works fine for me and I also can get VERY consistent results from battery to battery.

It just seems lots of people are spending money on these lipo alarms and the method used,is very unreliable.I was just curious if there were any specific reasons why one hasn't been designed this way.Everyone tracks mah and uses mah as the basis for the 80% rule,seems like a natural progresson to track mah instead of V
When I change my flying style, I'll lower my flight times until I can charge the packs and see how many mah I'm consuming. Same thing for changes in the heli that would increase the current draw. Run shorter flights until the consumption can be measured.
actually,I will add,this was what I was talking about,no need to "guess" how much shorter to make your flight,and you wont have to wait till you re-charge the battery to find the results,you will know right away.that was one of my points,it would eliminate lots of guess work and trial and error.but you could do that with an Eagle tree3 now anyway so thats neither here nor there.I had planned to get an eagle tree but 2 new helis side tracked that plan for the moment.I still would love to have one

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01-15-2009 01:31 PM  9 years agoPost 15
Melnic

rrElite Veteran

Columbia, MD,USA

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Hmm, what is more accurate, your estimation of the battery pack mAh size or just measuring the voltage of the battery pack under load?

Sure seems that a voltage under load is simple and effective?
Or are you arguing that it is not?

I contend that the market of RC users are not able or educated enough to estimate their mAh capacity and would not be able to use such a device EVEN IF it is better than just measuring battery voltage.

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01-15-2009 01:49 PM  9 years agoPost 16
slider46

rrProfessor

Ocala Florida

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Personally, I use the timer on my DX7 radio, and I have to say my internal body timer tells me when the heli has been flying to the 80% rule usually. I can hear and feel the difference in the heli at that point. Adding another electrical device to the heli (weight) doesn't interest me at all, it's just something else to go wrong/break. I am comfortable with what I use and my senses.....

Tom..... No "D" flying....

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01-15-2009 02:26 PM  9 years agoPost 17
Melnic

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Columbia, MD,USA

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Do you guys use the "throttle reduce" feature in your ESC?

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01-15-2009 02:32 PM  9 years agoPost 18
GyroFreak

rrProfessor

Orlando Florida ...28N 81W

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I see what you mean I found the $70 for the data logger ridiculous
Keep in mind that the Eagletree logs amps being used during flight, battery voltage, RPM, 3 X temp, GPS, all in a package the size of a matchbook. I fly it on a 450 and the weight/size is not noticeable but it gives me great data on every flight to help fine tune or diagnose a potential problem. I think the $70 is a great price for what you get. I have one on each of my electrics, T-450 and Razor 600E.
Course I'm a gadget guy and love this stuff.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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01-15-2009 11:06 PM  9 years agoPost 19
fenderstrat

rrProfessor

Aston,Pa

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How do would you accomodate a change in pack size? Its common to fly more than one pack size on the same heli.
very simple,have say 6 presets,you could preset in 6 different mah settings and scroll through them with the touch of a button,you would be able to select different settings in seconds.
With my packs I keep them cool and rarely run them past 80%. I try not to push them thier limits very often if at all. For me getting the most out of my packs is more about the number of flights, than the number of minutes. Staying at some vague number, between 70% and 80% capacity helps with that goal, moreso that running them down the exactly 80% every run.
you wouldn't HAVE to set it for 80%,you could set it for any % you want 60%, 70% 67% anything
I contend that the market of RC users are not able or educated enough to estimate their mAh capacity and would not be able to use such a device EVEN IF it is better than just measuring battery voltage.
is this a serious statement?if it is,I would really have to disagree,I think the average modeler and especially heli guys are extremely intelligent and more than capable of keeping track of the MAH in a battery,everyone is doing it now,tracking mah,we are just using a trial and error method.whats so hard about estimating your MAH capacity??take the rated capactity and multiply by .8(or however much you want to use),I'm not sure I'm following you on this one

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01-15-2009 11:28 PM  9 years agoPost 20
Gregor99

rrElite Veteran

Western Wa

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Now that I've slept on it, I have some more thoughts. First off, yes I do like the idea but there are a few implimentation details that push up the cost. Presets would work, but then you'd need a way to configure the presents, either USB connection, or screen on the device. Either way, it drives up the cost. Remember that a good 3 stage lipo alarm with chime and LEDs can be had for about $10. A USB interface or LCD screen alone are likely more than double that.

Here's what I woke up thinking about. Eagletree already has a telemetry module.

http://www.eagletreesystems.com/Pro/pro.htm

The existing module wouldn't be a perfect solution, but the underlying technology could be adapted to a low cost limited function telemetry. Initally, the cost would he prohibitive, but over time if they marketed strongly to electric fliers the cost would come down.

Honestly, I think this is an area that Futaba and Spektrum should be expanding into. They are already providing communicaitons in one direction. Plus the readout and controls could be all done on the radio instead of clipping on an extra device to both the heli and the Tx.

I don't expect to see this anytime soon. But as the manufactures run out new features to add to thier new radios, then this could become an attractive feature set to generate new sales. Judging by the latest update to the DX7, it appears Spektrum is out ideas. Or at least out if ideas that are ready to take to market.

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