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-   -   What do you use for powering your radio/servos? (http://www.Wattflyer.com/forums/showthread.php?t=74308)

NJSwede 08-15-2014 10:10 PM

What do you use for powering your radio/servos?
 
Just out of curiosity (and some Friday fun), what do you use for powering your receivers/servos?

I'll go first:

Foamies and balsa up to 51" wingspan: ESC built-in BEC. Typically ZTW or Castle
58" Edge: 10A Castle Creations BEC
Beast 60e (58" wing span biplane with quadruple aileron servos): 2x redundant 2s 1800mAh LiPo through powersafe.
71" Slick: 20A Castle Creations BEC
72" Extra (gasser): 2x redundant 2s 2300mAh LiFe through batteryshare.
76" Edge: Single 2s 2200mAh LiPo (will upgrade to redundant "one of these days...")
88" Slick (gasser): 2x redundant 2s 2200mAh LiPo.

JetPlaneFlyer 08-16-2014 12:15 AM

Smaller than about 48" I'll just use the BEC in the ESC but I make sure it's a good switching type one.

Some of my 48" 3D models i have a CC 10A BEC in, as i do my 51" models. That's the biggest I've got on fixed wing.

On the helis I have a CC 10A BEC on the 500, a CC BEC Pro (20A) on the 600 and unregulated 2s 2200mAh LiPo on the 700 (HV servos on that one).

kyleservicetech 08-16-2014 01:38 AM

Kyleservicetechs receiver power systems
 
My models 1500 Watts and smaller use the Castle Creations 10 Amp uBEC. These uBEC's have been flawless over about 5 years. I've got 10 of them in various electric models.

As for my giant scale models, 2500 and 3000 Watts, again, they use the Castle Creations 10 Amp uBEC, with the uBEC connected to the "Center" of a 10S and 12S battery packs. Added to the uBEC is a two cell 2300 Mah A123 battery pack as a backup unit.

The two cell A123's are isolated from the uBEC with two series 10 Amp Silicon Diodes, located in series with the A123 battery pack red lead. This drops the output voltage of the A123 pack to about 5.6 Volts DC, below the set point of 6.50 Volts DC coming from the CC uBEC. This scheme has a battery undervoltage alarm with a little 8 pin PicChip microcontroller that measures the receiver voltage about 4000 times per second. If the voltage EVER drops below 6.0 Volts DC, the under voltage alarm shows just how low the battery voltage dropped. After over 500 flights in two giant scale models, those under voltage alarms have never gone off with the Castle Creations uBEC.

I did have an undervoltage alarm indication after a flight on a Common Sense switching BEC on the Giant Big Stick model. My monitor showed that the Common Sense output had dropped to 5.8 Volts DC on one flight. That Common Sense unit was replaced with the Castle Creations uBEC, and no more problems were noted.

The maximum peak current pulled by the Giant Big Sticks seven Hitec 645MG servos has been measured at 14 Amps, on my $$$$ Fluke 87V digital multimeter, with its millisecond measuring peak hold feature.

After some 100 flights, it only takes about 150 or 200 Mah to "Top Off" the A123 battery packs. This is due to operating the receiver only from the A123 packs during testing, or while powering everything up.

This thread shows how the CC uBEC and two cell A123 backup battery was wired up:
http://www.wattflyer.com/forums/showthread.php?t=63794

NJSwede 08-16-2014 01:44 AM

Bonus question: If you run separate receiver batteries, after how many flights do you recharge them?

My answer: Before each outing to the field. I rarely put more than 5 flights on each plane in an outing.

kyleservicetech 08-16-2014 01:58 AM

Quote:

Originally Posted by NJSwede (Post 955295)
Bonus question: If you run separate receiver batteries, after how many flights do you recharge them?

My answer: Before each outing to the field. I rarely put more than 5 flights on each plane in an outing.

A number of my club members have gone to either LiFe or A123 receiver packs for their gasser/glow powered models. I've instructed them to "Top Off" their LiFe or A123 packs after a day's flying. These cells "Hold 95% of their charge" for a year or more, so they don't need to be charged before a days flying.

My personal rule (And what I tell my club members) is to NEVER use more than 50% of the batteries Mah capacity during any days flying, just in case you do a whole lot more acrobatics and so on. That's a safety factor of 50%.

There are so many advantages of the LiFe or especially the 2300 Mah A123 packs compared to the "AA" Nih packs, a lot of my club members are no longer using the Nih packs. When those LiFe/A123 battery packs hit 3.6 Volts DC per cell, they are fully charged. Simple as that. Compare that to fast charging a Nih battery pack, where you've got to worry about false peaks on some of those cheaper battery chargers. I've run across cases where one of those cheap battery chargers didn't fully charge a Nih battery pack during the charging process.

Little bit of reading info on the use of those A123's for giant scale model receiver power systems.
http://hangtimes.com/a123_batteries_for_giants_faq.html

fhhuber 08-16-2014 02:35 AM

depends on the airplane.... anything from 4 cell 200 mah 1/2 N cell NiCd to 4500 mah LiFe or LiPo via the ESC's BEC or a stand alone regulator.

Whatever will supply adequate current without excess weight.

carpetbagger 08-16-2014 02:52 AM

Nothing big in my squadron so I just power up with the ESC lead. Thinking I might stuff a standard RX pack in a couple E-gliders on the workbench since those buggers can stay up a looonnngg time.

kyleservicetech 08-16-2014 03:20 AM

Quote:

Originally Posted by carpetbagger (Post 955304)
Nothing big in my squadron so I just power up with the ESC lead. Thinking I might stuff a standard RX pack in a couple E-gliders on the workbench since those buggers can stay up a looonnngg time.

Yeah
Back in the mid 1980's I had a number of electrified sailplanes. Receiver power was a Nicad pack. Those sailplanes generally do not get a lot of operation of their elevator/rudder commands, so the overall milliampere hours pulled out of the battery pack was pretty low.

I had a number of two hour plus flights on my 10 foot wingspan Craftaire Viking Sailplanes.


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