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HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › LiFe battery low voltage.
12-31-2012 08:43 PM  5 years agoPost 1
kruuuzn

rrKey Veteran

Traverse City, MI

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I just installed telemetry on my gasser using a LiFe battery and would like to set a low voltage alarm in my radio. I've read that a LiFe battery will hold a constant 6.6 volts until it drops rapidly at the end of the charge. Is using a low voltage alarm even feasible with this type of battery?

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12-31-2012 10:40 PM  5 years agoPost 2
Four Stroker

rrElite Veteran

Atlanta

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It depends on the load like any battery. 1500 mAh removed from an A123 pack at 2.3 A gives 6.4 volts. But this is a constant load.

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12-31-2012 11:30 PM  5 years agoPost 3
Dr.Ben

rrMaster

Richmond, VA, USA

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6.4 V.....maybe for the alarm.....but I have seen how fast LiFE voltage plummets over the edge of the "cliff". If that alarms goes off, you better get to the ground FAST.

The safest bet for this chemistry is to know what you take out of the pack each flight and cycle routinely to determine what percentage of the pack's TRUE capacity, versus labeled capacity, you are pulling out.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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12-31-2012 11:44 PM  5 years agoPost 4
darren heaver

rrApprentice

rochester, kent, england.

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Life alarm !!
I use li-fe batteries on most of my heli's now and have just set them to run on my 18 mz with telemetery I have set the low voltage alarm at 6.3v and this gives me about 20-30% left in the battery. So enough for a safe landing and a bit more.
Hope this helps !!!

" one day I will learn to fly till then I will just hover"

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12-31-2012 11:53 PM  5 years agoPost 5
kruuuzn

rrKey Veteran

Traverse City, MI

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Thanks Ben,
I'm running a generator on my gasser so the battery should never discharge. I was hoping to use the alarm as a fail safe should the system ever stop charging unexpectedly.
Maybe I should just get in a habit of checking the battery for full charge every 3 or 4 flights eh?

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12-31-2012 11:57 PM  5 years agoPost 6
kruuuzn

rrKey Veteran

Traverse City, MI

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Yes it does. Thanks Darren!

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01-01-2013 12:01 AM  5 years agoPost 7
rbort

rrProfessor

Franklin, MA - USA

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Alarm
I would set the alarm to 6v myself. It should never reach there or trigger it if you're using a generator. Should expect to see your pack hover at around 6.5v after several flights would be my best guess.

If you have telemetry, just watch it on the TX. When you start the engine and start to spool up, you should see the voltage rise. If so then all is good and technically speaking it should stay at the risen voltage most of the time in flight with the exception of heavy loads might cause a tiny drop.

-=>Raja.

MA 1005 Hanson 280, 4220 flts
Spectra 27 3DMax, 3310 flts
Whiplash V1-2 Hanson 300, 1618 flts
Whiplash V2 Hanson 300, 473 flts

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01-01-2013 07:28 PM  5 years agoPost 8
darren heaver

rrApprentice

rochester, kent, england.

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Battery alarm
Don't think I would personally set it at 6.0v as I was playing on the ground setting a heli up a few weeks back and had it set to 6.0v and ignored it for a couple of mins as was only setting up on the ground, the next thing I knew it started glitching and then went into F/S ............ So think I would go a bit higher ;-) for what it's worth !!!

Just my opinion ........

" one day I will learn to fly till then I will just hover"

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HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › LiFe battery low voltage.
01-01-2013 08:47 PM  5 years ago •• Post 9 ••
d_wheel

rrVeteran

Deep in the heart of Texas.

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Like most things, it probably depends... I am using a 2s LiFe pack on one of my birds. An hour or two after charging, resting on the bench, it shows the following voltage:
With my analog meter - 6.8 volts. With my digital meter - 6.72 volts. On the Spektrum telemetry - 6.6 volts. In flight, I get an alarm if the trigger voltage is higher then 6.1 volts. The Iphone log shows 6.2 to 6.3 volts during heavy use.

All this being said, set your alarm voltage according to the accuracy of your sensor. A good place to start might be around 6.2 to 6.3 volts volts. If you get alarms, lower it a bit. If not, review your flight log and set it to about .1 volts under the lowest voltage in the log.

Later;

D.W.

Gettin old aint for sissies!

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01-01-2013 10:39 PM  5 years agoPost 10
rbort

rrProfessor

Franklin, MA - USA

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Good advice guys
If you're getting 6.2 to 6.3 in flight, then 6 to 6.1 sounds good. The idea is that it won't trigger unless there is something wrong with the charging system. And while up in flight it will probably never reach this low, my guess would be only at idle when the charging system is only making 5v not enough to hold the battery voltage up and then you do some 3D autos like piro flips on the way down or something and it can trigger the alarm if set too high.

All the best guys and have fun flying

-=>Raja.

MA 1005 Hanson 280, 4220 flts
Spectra 27 3DMax, 3310 flts
Whiplash V1-2 Hanson 300, 1618 flts
Whiplash V2 Hanson 300, 473 flts

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