Voltage drop under load

[ShaneM]

Hi guys

my set up is;

50cc Extra 300 from OMP..
TechaeroIBEC
R7000sb Futaba RX - Futaba 14SG

2x 2300mah NoBSBatteries A123's

JR Gold switches

From the Battery I have Deans connected to the JR switchs..... All solder joints are good and hot.. No issues there with connections... Also no stalling servos either.

When flying and performing snaps, or rolling harriers my 14SG telemetry is reading back a voltage drop of 5.5V ! How can this be possible with two batteries and two separate switches feeding the RX through 2 ports?

 

[ChickenBalls]

Sub'd

 

[rcpilotacro]

It's trick question ! Voltage drop is due to servo draw ! Period,

 

[jhelber08]

Sounds about right...I had a 100cc extra with telemetry and 2 fromeco a123's with a powersafe rx. It wasn't uncommon to see a lowest voltage of around 4.9V during a hard flight. It was kinda scary at first but never had an issue as far as brownouts or black outs.

 

[ericb]

Pretty normal. The biggest bottle neck in your setup is the switches.

 

[ShaneM]

Thanks guys.

 

[stangflyer]

5.5 volts is actually pretty good if you're 3d'ing it pretty hard. Most receivers from what I am told do not have an issue with brown out or lose signal unless the voltage "AT" the receiver is around 3.3 or less volts. I am sure the Futaba and JR guys can confirm this. I just bought a new JR XG11 so I am not too well versed in all the parameters yet. I can say however that with my Hitec rx's, right around that voltage is the danger point. If it helps you compare, I have a 30% Pilot Edge 540 with a DLE 55, using all Hitec 7954 servos. Fromeco Relion 7.4 volt 2600 mah packs. (2) on the receiver coupled through the Smart Fly Power Expander Pro. I have personally beat the snot outta that plane and after a typical day of "HARD" flying, usually 5 to 6, 12 minute flights, both rx. packs are still registering nearly equal voltage. Upon charging them for the next outing, usually take about 700 to 800 mah's to top off. I have not seen anything under 5.0 volts at any given time ever.

Hope this helps...

 

[jamesrxx951]

5.5 volts is actually pretty good if you're 3d'ing it pretty hard. Most receivers from what I am told do not have an issue with brown out or lose signal unless the voltage "AT" the receiver is around 3.3 or less volts. I am sure the Futaba and JR guys can confirm this. I just bought a new JR XG11 so I am not too well versed in all the parameters yet. I can say however that with my Hitec rx's, right around that voltage is the danger point. If it helps you compare, I have a 30% Pilot Edge 540 with a DLE 55, using all Hitec 7954 servos. Fromeco Relion 7.4 volt 2600 mah packs. (2) on the receiver coupled through the Smart Fly Power Expander Pro. I have personally beat the snot outta that plane and after a typical day of "HARD" flying, usually 5 to 6, 12 minute flights, both rx. packs are still registering nearly equal voltage. Upon charging them for the next outing, usually take about 700 to 800 mah's to top off. I have not seen anything under 5.0 volts at any given time ever.

Hope this helps...

I think you will love that XG11. Very happy with mine. When you monitor the receiver voltage using a power expander like the smart fly you will not get a true reading of what the battery voltage is though. The recievers are fed a regulated 5.0V and should remain pretty constant unless the pack gets below that. The only way I can think of monitoring actual receiver pack voltage is to not power up the receiver with the regulated power and straight from the battery source or get the inline battery voltage adaptors http://www.jramericas.com/233828/JRP03444/?pcat=333

 

[Taildraggerrc]

I am running the xg11 as well. On my 108" extra with 2x 2500mah a123 and power safe 11 channel rx I get a one tenth voltage drop during a crankshaft! I'm so,d on these type of receivers..

 

[stangflyer]

I think you will love that XG11. Very happy with mine. When you monitor the receiver voltage using a power expander like the smart fly you will not get a true reading of what the battery voltage is though. The recievers are fed a regulated 5.0V and should remain pretty constant unless the pack gets below that. The only way I can think of monitoring actual receiver pack voltage is to not power up the receiver with the regulated power and straight from the battery source or get the inline battery voltage adaptors http://www.jramericas.com/233828/JRP03444/?pcat=333

I hope so too. I have all my other planes already setup on the Hitec X9. But the new PAU will have the JR system in it. You are absolutely correct on the fed voltage to the receiver from the smart fly. However with a battery lead direct to telemetry, readings are the same or close to constant 5 volt. I may have to double check that to make sure it is operating as I believe it to be. Thank you for pointing this out.