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Old Feb 06, 2010, 11:17 AM
JJJNYC is offline
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Talk to me Goose ...
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Quanum battery voltage telemetry - and 'voltage under load' question ...


To a Lipo novice, this seems like a great idea - sending real time accurate Lipo voltage to a display on your transmitter.

http://www.hobbyking.com/hobbyking/s...dProduct=10343

Two questions -

1. Has anyone used it/performance thoughts?

2. If our goal is to never take Lipos below 80%, and as this will measure voltage of your Lipos under load (assuming you read the display while using battery power), what reading of voltage per cell would be the minimum without damaging our Lipos?

As a note, question 2 is because I have never tested a Lipo under load - worried that under load has various interpretations depending on 'load' ... i.e. when mfg'ers say, "Never go below 3 volts per-cell under load," will any load cause the voltage reading to be 3.0v while the non-load reading would be closer to 3.7v? Or just a large load, for example where your motor has been drawing maximum Amps for over 30 seconds?

Just trying to figure out the operating parameters of this device to see if it is worth the investment ...

Appreciate your thoughts - thx!
- Jarrett
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Old Feb 06, 2010, 12:13 PM
everydayflyer is offline
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I use data loggers and experience. No way I can watch a display while I am flying under max power.I guess you could climb and glide and glance at the % display .
Old Feb 06, 2010, 04:01 PM
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Agree. Totally useless and a hazard. Same goes for all the telemetry that goes with the new Aurora 9 radio. You really shouldn't be looking at the screen while flying.

Use a watt meter, data logger or charger to determine your 80% discharge flight time, use a timer for every flight.

Also, having a cheap 2.4Ghz transmitter right next to your 2.4Ghz receiver is not a good idea, unless you want to overload the receiver and totally loose control of your aircraft. I'd be curious if those using it actually measured packet loss or not (I suspect not ... ). Don't forget that HK is keen on deleting negative reviews, especially for new products.
Last edited by marc1; Feb 07, 2010 at 02:31 AM.
Old Feb 07, 2010, 02:23 AM
Ira NZ is offline
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Quote:
Originally Posted by marc1 View Post
Also, having a cheap 2.4Ghz transmitter right next to your 2.4Ghz receiver is not a good idea, unless you want to overload the receiver and totally loose control of your aircraft. I'd be curious if those using it actually measured packet loss or not (I suspect not ... ). Don't forget that HK is keen on deleting negative reviews, especially for new products.
Yet another reason that 35/72mhz etc is better than 2.4ghz.

What we really need is something like this so you can fly and still see all the relevant telemetry.
Old Feb 07, 2010, 09:10 AM
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"..To a Lipo novice, this seems like a great idea..."

It might be because you are a novice. And take no insult from my saying that.

I like the data from a power data recorder that is analyzed after flight. That will not normally give you a continuous and full duration voltage data stream on each individual cell throughout the flight. If I wanted to study cell voltages under load to look for a weak cell or something like that, I would prefer to do it in static testing, not while I was trying to fly a plane.

Jack
Old Feb 07, 2010, 11:36 AM
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They also make data recorders for cell voltages ... http://www.hobbyking.com/hobbyking/s...idProduct=9282 if that is what you are concerned about.
Old Feb 08, 2010, 01:55 AM
JJJNYC is offline
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Talk to me Goose ...
Appreciate the replies ... Looking at the website picture, the total voltage of the Lipo seems to be in as big a font as the timer I currently use - I guess a countdown timer with an audio alarm would be optimal (and probably what you all use, I am guessing)? Otherwise, this is no different ...

As an aside, more of a curiosity question, is there an answer to the load question I posed, or is 'load' too large of a variable?

Really appreciate the thoughts,
- Jarrett
Old Feb 08, 2010, 02:01 AM
Ira NZ is offline
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Quote:
Originally Posted by JJJNYC View Post
As an aside, more of a curiosity question, is there an answer to the load question I posed, or is 'load' too large of a variable?
Pretty much, yeah, voltage drop, obviously, depends hugely on how much current that load is.

I think the best would be a simple meter that displays how many MAH have been drawn from the battery. Then you can just look at your battery say, "It's a 2500mah, I'll fly to 1750." and just land when the MAH reading hits 1750.

If you try to go with voltage under load you'd need to do something like go to WOT, watch the voltage readout, wait a second for it to stabilise...Nah, easier just to land at 1750.
Old Feb 08, 2010, 02:23 AM
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Quote:
Low voltage alarm. Know when your pack voltage is about to drop.
It does have alarm, I will probably test a unit for my heli's later this spring.
(Flying helis, the flighttime differs alot, its often I come back home with a pack that is 40-50% charged because I flew soft)
Old Feb 08, 2010, 03:08 PM
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I think it's a pretty cool device if you a a FB or two with you. You don't have to put it on your Tx and if a buddy can monitor voltage for you while in flight it's a pretty cool gadget.
Old Feb 09, 2010, 01:47 PM
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Multiplex M-link and Jeti duplex emit an audible beep when the pack reaches a pre determined voltage or Mah used value, no need to look at the screen, much much much better than timing your flights, timing is a very blunt instrument, it all depends on your flying style for the given flight, no two flights are ever the same.
Old Feb 09, 2010, 02:43 PM
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Quote:
Originally Posted by stew007 View Post
Multiplex M-link and Jeti duplex emit an audible beep when the pack reaches a pre determined voltage or Mah used value, no need to look at the screen, much much much better than timing your flights, timing is a very blunt instrument, it all depends on your flying style for the given flight, no two flights are ever the same.
I like the idea of a capacity alarm as opposed to a voltage alarm. A voltage alarm would be useless for me for the same reason LVC is useless to me. Both can go off prematurely if high current draw (voltage drop) is applied during a flight.
Old Feb 09, 2010, 09:47 PM
JJJNYC is offline
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Talk to me Goose ...
Someone showed up using this device at the field and it seemed to work great - but he too was not sure of what minimum voltage should be (I held the device when he flew - that worked great as we always seem to have someone standing around at my field).

So, I would love some more thoughts on question 2 ... i.e. how would you use this device under load? I have never tested a Lipo under load - worried that under load has various interpretations depending on 'load' ... i.e. when mfg'ers say, "Never go below 3 volts per-cell under load," will any load cause the voltage reading to be 3.0v while the non-load reading would be closer to 3.7v? Or just a large load, for example where your motor has been drawing maximum Amps for over 30 seconds?

Translation - A friend already owns one and I am going to try it out - just trying to learn what the most effective way to use it is (assume someone else will be reading the meter) ...

Thanks!
Old Feb 09, 2010, 11:20 PM
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I have never tried one of these things but it does look like a cool new gadget. I am not sure I would want to spend $100 on it. If you have a cell logger or some thing that measures cell voltages you could run your lipo down to LVC and see where it is under load.
Old Mar 09, 2010, 01:09 AM
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I purchased one and tested it yesterday at the field. Works very well. Low voltage alarm is at 9.5 volts for a 3 cell battery which is a bit too late, but still I find the device very useful. Will need to use it a bit more on my foamies before I move it to my larger planes. They are $69 plus shipping at HK. They show as $99 but the price changes once you put it in your cart.


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