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RC Radios, Transmitters, Receivers, Servos, gyros Discussion all about rc radios, transmitters, receivers, servos, etc.

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Old 09-21-2012, 02:37 AM   #1
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Default JR receiver with LiPo battery

I would like to use 2S 2100 ma LiPo battery to power my nitro plane receiver. So far I have not succeeded . When I plug the battery with a UBEC LED blinks once and nothing happens. Battery is fully charged 2S 8.4 V UBEC output is 5.2 V at the receiver.
When I plug in NiHm battery 5.33 V it works ,it binds and servos work. Any suggestions would be appreciated .

Thanks in advance Greg
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Old 09-21-2012, 10:46 PM   #2
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Originally Posted by FWCXC View Post
I would like to use 2S 2100 ma LiPo battery to power my nitro plane receiver. So far I have not succeeded .
When I plug the battery with a UBEC LED blinks once and nothing happens.
Battery is fully charged 2S 8.4 V UBEC output is 5.2 V at the receiver.
When I plug in NiHm battery 5.33 V it works ,it binds and servos work. Any suggestions would be appreciated. Thanks in advance Greg
"When I plug the battery with a UBEC LED blinks once and nothing happens"
Without knowing which of the many many brands and models of UBEC it is, we are unable to help,
this as UBEC/SBEC etc all have different set up modes/LED indicators.

The instructions should give an indication of what the LED On/Off/ Flash etc is indicating
- have you checked that the Red/Black leads are in line with the other leads lugged into the rx?

. EPA, ATV, Dual & Triple Rates, Expo Differences & Caution + ESC / BEC Set Up

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Alan's Hobby, Model & RC FAQ Web Links
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Old 09-22-2012, 12:55 AM   #3
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Originally Posted by FWCXC View Post
I would like to use 2S 2100 ma LiPo battery to power my nitro plane receiver. So far I have not succeeded . When I plug the battery with a UBEC LED blinks once and nothing happens. Battery is fully charged 2S 8.4 V UBEC output is 5.2 V at the receiver.
When I plug in NiHm battery 5.33 V it works ,it binds and servos work. Any suggestions would be appreciated .

Thanks in advance Greg
H'mmm
You might want to check that uBEC under a load current of several amperes or so. These uBEC's may require a minimum "headroom" voltage above the output voltaqe you are trying to obtain.

How many servos and what type servos are you running?

If you are in the USA, Radio Shack has a resistor that will work. One resistor will pull 5 amps, two resistors in series will pull 2.5 Amps. Just take an old servo connector, and clip the resistor (resistors) to the red and black wires. A good uBEC will not drop more than a few tenths of a volt under this type of load.

Also, out of curiosity, check the 5 Volts DC output voltage under load on your digital multimeters AC range. The AC voltage should be very very low. (Most quality digital meters will block the DC voltage component while measuring AC voltages.)

Take a look:
http://www.radioshack.com/product/in...ductId=2062290

As for me, I use those A123 cells for receiver power. Their lower voltage allow a direct replacement of a 5 cell Nickel Hydride receiver battery pack, without requiring a voltage regulator. The LiFe batteries have similar chemistry with the same voltage. A lot of my club members running gassers are using a 2000 Mah or higher LiFe battery to power both their receiver and ignition systems. I've checked several LiFe batteries. They will put out 13 Amps momentary with little voltage drop. Take another look:
http://www.wattflyer.com/forums/showthread.php?t=67896

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Old 09-22-2012, 01:13 AM   #4
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Thanks for responding. I have checked and double checked that the leads are correctly plugged in. I have three UBEC's one is Hextronik 3A 5A max and another HK 3A 5Amax which are similar ,HK one has choke .And Turnigy UBEC 8A 15A max.
The small ones have LED's when on ,Turnigy has also voltage monitor and a switch.
I believed that the Voltage regulator is to reduce DC voltage from whatever battery I am using (6 -24V)to 5V or 6V with my receiver .

Greg
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Old 09-22-2012, 01:19 AM   #5
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Originally Posted by kyleservicetech View Post
H'mmm
You might want to check that uBEC under a load current of several amperes or so. These uBEC's may require a minimum "headroom" voltage above the output voltaqe you are trying to obtain.

How many servos and what type servos are you running?

If you are in the USA, Radio Shack has a resistor that will work. One resistor will pull 5 amps, two resistors in series will pull 2.5 Amps. Just take an old servo connector, and clip the resistor (resistors) to the red and black wires. A good uBEC will not drop more than a few tenths of a volt under this type of load.

Also, out of curiosity, check the 5 Volts DC output voltage under load on your digital multimeters AC range. The AC voltage should be very very low. (Most quality digital meters will block the DC voltage component while measuring AC voltages.)

Take a look:
http://www.radioshack.com/product/in...ductId=2062290

As for me, I use those A123 cells for receiver power. Their lower voltage allow a direct replacement of a 5 cell Nickel Hydride receiver battery pack, without requiring a voltage regulator. The LiFe batteries have similar chemistry with the same voltage. A lot of my club members running gassers are using a 2000 Mah or higher LiFe battery to power both their receiver and ignition systems. I've checked several LiFe batteries. They will put out 13 Amps momentary with little voltage drop. Take another look:
http://www.wattflyer.com/forums/showthread.php?t=67896
Hi Kyle I have two 123 2000ma battery's would they work with old analog servos? I also run Spectrum7000 receiver?
Greg
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Old 09-22-2012, 01:26 AM   #6
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Originally Posted by FWCXC View Post
Hi Kyle I have two 123 2000ma battery's would they work with old analog servos? I also run Spectrum7000 receiver?
Greg
Good question. Some of those older analog servos don't like voltages much above a 4 cell receiver battery.

If you've used a 5 cell Nih battery pack with success, those A123 batteries are a direct drop in, since these two battery chemistries have virtually identical voltage discharge curves.

Those A123 cells are available from www.voltmanbatteries.com at $9.99 each cell plus shipping. I've purchased some 50 cells from this place, and other club members have also purchased a total of some 50 cells. It's a good place to work with, and they are in the USA. Just wish I worked for them.

Take a look at the discharge curves of a two cell 2300 mah A123 pack, versus a 5 cell sub C Nih battery pack, attached.

DennyV


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Old 09-22-2012, 02:40 AM   #7
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Thanks Danny
This is good info and 123's are better then LiPo's anyway .

Greg
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Old 09-22-2012, 05:03 AM   #8
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Originally Posted by FWCXC View Post
Thanks Danny
This is good info and 123's are better then LiPo's anyway .

Greg
Yeah
LiPo's have it over the A123's for physical size and voltage output for electric motor power.

On the other hand, those A123 cells don't seem to wear out, and they have zero fire hazard. My five year old A123 6S2P packs have identical performance at 30 Amps per cell as some brand new purchased this summer. They've got over 300 flights on them.

As for receiver power, you are never going to overload an A123 pack due to servo loads. These cells will burn up the servo wires first. I've seen it happen, when a servo dead shorted.

You just can't forget and leave the receiver switch on. I've done this twice, and the A123 cells kept going for a year or three, but lost 30% of their amp hours after a few months. Very strange, they still put out the same voltage at 30 amps, the only effect was the 30% loss of capacity. Finally replaced them several years later.

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