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Old Sep 16, 2012, 08:31 PM
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FWCXC's Avatar
London Ont.
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Using LiPo for Rx

I seen the opportunity to use 2 C LiPo batterie for my RC planes as a better choice then NiCad's .So I bought two Zippy 2100 ma batteries, I also bought UBEC to lower the voltage to the receiver. I am flying Spectrum/JR system. I plugged it in receiver blinks once and the satellite is blinking intermittently. It does not work. As soon as I hooked up NiCad batterie it worked again?
Any help or suggestions would be appreciated.
Greg
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Old Sep 16, 2012, 09:49 PM
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Quote:
Originally Posted by FWCXC View Post
I seen the opportunity to use 2 C LiPo batterie for my RC planes as a better choice then NiCad's .So I bought two Zippy 2100 ma batteries, I also bought UBEC to lower the voltage to the receiver. I am flying Spectrum/JR system. I plugged it in receiver blinks once and the satellite is blinking intermittently. It does not work. As soon as I hooked up NiCad batterie it worked again?
Any help or suggestions would be appreciated.
Greg
how did you wire the UBEC?

see if this helps:

External UBEC "How To" (5 min 27 sec)
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Old Sep 16, 2012, 10:02 PM
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rcalldaylong Thanks this is great info. I am fairly new to electric's and have to learn a lot yet. I'll give it a try.
Greg
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Old Sep 17, 2012, 06:05 AM
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Did you charge the LiPo's before you tried to use them? I know this seems obvious but sometimes we forget.

Also you wrote "2 C". Did you mean "2S"? (two cell.)

Glen
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Old Sep 17, 2012, 10:03 AM
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Using a lipo for a receiver battery and having to add a regulator makes verl little sense when a 2S LiFe pack will be safer and doesn't need a regulator (BEC) if the servos are rated for 5 cell (6V nominal) operation. Just about any lipo charger on the market has LiFe/A123 settings.
Pete
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Old Sep 17, 2012, 10:20 AM
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Originally Posted by pilotpete2 View Post
Using a lipo for a receiver battery and having to add a regulator makes verl little sense when a 2S LiFe pack will be safer and doesn't need a regulator (BEC) if the servos are rated for 5 cell (6V nominal) operation. Just about any lipo charger on the market has LiFe/A123 settings.
Pete
Good advice but on a side note not all servos rated for 6V operation are happy with LiFe batteries, most but not all. Personally I'm using Hitec HV servos with a 2S lipo in all my new stuff. They even have a low cost HV std analog servo now.
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Old Sep 17, 2012, 11:03 AM
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I've had good luck running nominal 6.6V, even on some old ATX 94102 that were the last of the old style ATX style connector and Hitec sport servos such as the HS-325 and 475/485.
Moving forward I've switched to the Hitec HS-430HB HV servos for any standard sport application. A dual BB HV servo for $13.49, not too shabby.
Pete
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Old Sep 17, 2012, 04:48 PM
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Quote:
Originally Posted by ggcrandall1 View Post
Did you charge the LiPo's before you tried to use them? I know this seems obvious but sometimes we forget.

Also you wrote "2 C". Did you mean "2S"? (two cell.)

Glen
Yes it was a misprint it is 2S batterie . Do I use UBEC or SBEC?It seams UBEC is used for separate power to the receiver with electric powered airplanes and SBEC is used with glow planes.or I misunderstood ?

Quote:
Originally Posted by pilotpete2 View Post
Using a lipo for a receiver battery and having to add a regulator makes verl little sense when a 2S LiFe pack will be safer and doesn't need a regulator (BEC) if the servos are rated for 5 cell (6V nominal) operation. Just about any lipo charger on the market has LiFe/A123 settings.
Pete
I have couple of 123/ 6,6 Batteries but I thought that the high voltage would damage servos so I never used them?

Thanks for the replies

Greg
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Old Sep 17, 2012, 06:06 PM
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Originally Posted by FWCXC View Post
Yes it was a misprint it is 2S batterie . Do I use UBEC or SBEC?It seams UBEC is used for separate power to the receiver with electric powered airplanes and SBEC is used with glow planes.or I misunderstood ? Greg
UBEC and SBEC are different terms for the same thing. Basically it is the same circuit that is found in an ESC, just as a standalone device. I think SBEC came from Standalone Battery Eliminator Circuit and UBEC is the trade name of a particular brand. But UBEC has come to be used universally. Technically these devices are not battery eliminators but voltage regulators.

Glen
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Old Sep 17, 2012, 06:19 PM
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Hi Glen I think I understand that, but why when I connect 8V batterie with UBEC with a jumper at 5V (which is regulated power)the receiver does not respond and when the NiCad is connected it works? It does not matter what the battery power it is UBEC should deliver 5V? Fully charged NiCad batterie is 5.6V.


Greg
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Old Sep 17, 2012, 07:26 PM
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Have you checked the output of your BEC with a voltmeter?

This should ALWAYS be done on all new BECs and you should not rely on the QC at point of manufacture as some QC departments are iffy at best.

I've heard reports of BECs with either no or low output as well as BECs with far too high output that then smoked receiver and servos. Consequently, it is extremely wise to check first.

What specific BEC are you using? Are you sure that it is specified to work properly with 2S lipoly?

Mark
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Old Sep 17, 2012, 07:37 PM
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Also have you verified that your batteries are fully charged? Again verified with a volt meter.

Glen
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Old Sep 17, 2012, 08:32 PM
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Originally Posted by mrforsyth View Post
Have you checked the output of your BEC with a voltmeter?

This should ALWAYS be done on all new BECs and you should not rely on the QC at point of manufacture as some QC departments are iffy at best.

I've heard reports of BECs with either no or low output as well as BECs with far too high output that then smoked receiver and servos. Consequently, it is extremely wise to check first.

What specific BEC are you using? Are you sure that it is specified to work properly with 2S lipoly? I am using HK UBEC 2-6S 3A max5A

Mark
No I have not checked the voltage output.
Very good suggestions .Thanks
I am using HK 2-6S UBEC 3A max 5A
Quote:
Originally Posted by ggcrandall1 View Post
Also have you verified that your batteries are fully charged? Again verified with a volt meter.

Glen
The battery's were fully charged. I did verify voltage. 4.20 per Cell
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Old Sep 17, 2012, 08:45 PM
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2S and external BEC's are all I use in my fuel planes.
Long as its wired correctly yours should work.

I know, I know. we're doing it wrong not using Life but I don't have any on hand and am not buying them when I have lots of small 2S available.
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Old Sep 17, 2012, 08:52 PM
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I just checked the voltage leaving BEC it is 5.23 on one and 5.33 on the other?

Greg
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