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Old Feb 10, 2011, 07:09 PM
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Here it states the "average" Optima draws 60-70mA without the HTS sensor station hooked up. Not sure if that's a 7 or 9 channel. But then it says an Optima 9 with the HTS but no servos draws 220mA. I wonder how much more current is required when it's commanding Sx movement (less the actual Sx draw).
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Old Feb 10, 2011, 08:22 PM
Because I can!
joe1l's Avatar
USA, NJ, Chester
Joined Apr 2010
100 Posts
So i decided to do some testing...and it looks like it is as though!!

I the Optima 7, Optima 9, R6008HS, R6014HS and for kicks the Orange RX


All tests done with transmitters in helicopter mode no/dr no expo 100% travel 3 servo swash. Channe1 Ailerion, Chanel2 Elevator, Channel 6 pitch
All tests done using 2100mh Hyperion 2s 6.6v LiFE back, using identical power cable etc. All tests done with sticks moved in circles first number is slower circles avg , 2nd number is top avg when moving the sticks faster. On avg the the Optima's drew more current, but the current draw gap seemed to widen the more servos were added. For instance even though when I connected 3 servos on the optima 7/9 i would see spikes as higher than 4.5amps where as the spikes on the Futabas were much less. Even moving the sticks at normal rate in a circle on any of the futaba receivers, i'd see much lower average with the servos...the amperage would stay pretty steady between 1.6 and 2.1amp compared to the Optima which would jump around quick between 2.8~to over 4amps. If anything the numbers below for the Optima represent low avgs instead of incorporating the big spikes where the futabas show their upper limits.

Optima 7
with 1 INOLAB 760MG Server
1-1.5 amp
with 2 INOLAB 760MG Server
2.06-2.7 amp
with 3 INOLAB 760MG Server
2.5--3.7 amps


orange rx (high speed mode)
with 1 INOLAB 760MG Server
.5--.90 amp
with 2 INOLAB 760MG Server
.84--1.34 amp
with 3 INOLAB 760MG Server
1.8--2.6 amp

optima9
with 1 INOLAB 760MG Server
1.1--1.6 amp
with 2 INOLAB 760MG Server
2.02--2.70 amp
with 3 INOLAB 760MG Server
2.5--3.8 amp

R6008HS (normal mode)
with 1 INOLAB 760MG Server
.7--1 amp
with 2 INOLAB 760MG Server
1.11--2.1 amp
with 3 INOLAB 760MG Server
2.1--2.8 amp

R6014HS (high speed mode)
with 1 INOLAB 760MG Server
.8--.97 amp
with 2 INOLAB 760MG Server
1.1-2.0 amp
with 3 INOLAB 760MG Server
2.1--2.8 amp
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Old Feb 11, 2011, 04:24 AM
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thats interesting. Seems you do get what yo pay for huh?
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Old Feb 11, 2011, 09:44 AM
Because I can!
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USA, NJ, Chester
Joined Apr 2010
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Originally Posted by TimBle View Post
thats interesting. Seems you do get what yo pay for huh?
Thats not the point i was trying to make. I wanted to point out the difference in current draw between the systems using identical servos. The assumption is that the telemetry being the great feature that it is, has a drawback. I only wish i had a JR/Spectrum system to test with. Basically I was using 4 to 5 amps with just 3 servos. I didnt have a 4th of the same servo else i would be up over 6amps on the optima. Conclusion is the optima without SPC power will require closely 25% to 30% higher capacity power source to run same equipment. This is a very conservative number, if i were to compare the high spikes i saw on each system, it would be closer to 35% to 40%. I will probably like to re-do the tests again with another set of servos that i know draw much less current and see the difference as well as adding a small receiver capacitor to each and comparing results. I forgot to mention earlier that I even went as far as using a big 1.25f capacitor by Fromenco on most of my helicopters connected directly to the receiver, to help prevent power loss etc.

Mike this is the issue that needs some better documentation around! I'm quite positive the tests i did are easy enough to reproduce and that your numbers should not look too much different than mine.
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Old Feb 11, 2011, 10:09 AM
どうもありがとうミスターロボット
Wrend's Avatar
United States, IL
Joined Jul 2009
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That's kind of weird. You're looking at about a 1 amp higher drain rate with the Hitec RXs. Coupled with the higher brownout voltage, I can see how someone could get caught off guard.
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Old Feb 11, 2011, 11:56 AM
Because I can!
joe1l's Avatar
USA, NJ, Chester
Joined Apr 2010
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Quote:
Originally Posted by Wrend View Post
That's kind of weird. You're looking at about a 1 amp higher drain rate with the Hitec RXs. Coupled with the higher brownout voltage, I can see how someone could get caught off guard.
YEP!!! Mystery solved!!! The Hitec easily has over 1 to 2amps over the other. I was trying to leave out the big spikes for the Hitec. But spike to spike was probably 3.2 compared 5+amps. You can even see in this video the big spikes, even though he does not keep the camera constantly on it.
Take care the working voltage and current of your BEC. (4 min 56 sec)
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Old Feb 13, 2011, 11:50 AM
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what I was indicating is that the Himart Rep MikeBlackberry always uses the lower cost as a selling point. That lower cost comes at a price that is higher brown out voltage and higher current draw which could be due to several factors e.g. lower quality components or a less ribust design or simply the need to transmit back to Tx.

The impact on the end user is that a low battery warning with the telemetry is actually very critical. So your discovery is quite important and is something prospective buyers of telemetry Tx's should be aware of. One brand in particular is already know to be very sensitive to voltage and having Telemetry enable could increase tha sensitivity further
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Old Feb 13, 2011, 03:54 PM
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Joined Sep 2004
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I chose Turnigy 9X $55 radio. It functions as well as any high priced brands.
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Old Feb 13, 2011, 03:56 PM
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NorCal
Joined Oct 2001
3,755 Posts
Quote:
Originally Posted by John Kim View Post
I chose Turnigy 9X $55 radio. It functions as well as any high priced brands.
When it works.

And no, it's quality does not compare to Hitec A9, Futaba, Airtronics, JR. Not even close.
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Old Feb 13, 2011, 04:32 PM
Because I can!
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USA, NJ, Chester
Joined Apr 2010
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Quote:
Originally Posted by TimBle View Post
what I was indicating is that the Himart Rep MikeBlackberry always uses the lower cost as a selling point. That lower cost comes at a price that is higher brown out voltage and higher current draw which could be due to several factors e.g. lower quality components or a less ribust design or simply the need to transmit back to Tx.

The impact on the end user is that a low battery warning with the telemetry is actually very critical. So your discovery is quite important and is something prospective buyers of telemetry Tx's should be aware of. One brand in particular is already know to be very sensitive to voltage and having Telemetry enable could increase tha sensitivity further
Well, its funny because i started off just trying to learn more for my own good, almost to point that I was hoping to prove the A9 to be the un-matched choice. Instead I learned that value always has a way of punishing you later. I think all the 8FG needed was a slightly larger screen and i probably would have bought it from day 1
I"m not trying to bash the A9 or Hitec but to say i'm happy with them would be less than genuine. If anything I wanted to finally give the data that I wish I had when I was trying to trouble shoot the issue. I tried sharing some of the data on Helifreak recently and was told that my findings were in-fact common sense and that i should of known that the Optima recievers needed 30 to 40% more current So its quite nice to hear that my findings were important... For me i'm just happy to have finally realized, that it was not just my "rotten luck" that this stuff was happening!
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Old Feb 13, 2011, 09:30 PM
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Joined Apr 2007
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Quote:
Originally Posted by joe1l View Post
...
I tried sharing some of the data on Helifreak recently and was told that my findings were in-fact common sense and that i should of known that the Optima recievers needed 30 to 40% more current So its quite nice to hear that my findings were important... For me i'm just happy to have finally realized, that it was not just my "rotten luck" that this stuff was happening!
Telemetry requires more power, because the "receiver" now includes a transmitter. This is indeed not a surprise. So comparing an RX with telemetry, to one without, should always show the same result. And yes, I found out the hard way when I upgraded from Spektrum to Hitec. Fortunately, my plane floated nicely.

Next step is to compare a Spektrum setup with telemetry to Hitec. The Hitec unit always has voltage telemetry, while I gather that the Spektrum DX8 requires you to add another box.

To compensate, the Optima receivers include the SPC port so you can ensure that the receiver never browns out, no matter what the servo load. We can fault Hitec for not advertising this issue more diligently - but not for the basic design, which is susceptible to laws of physics!
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Old Feb 14, 2011, 07:03 AM
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Originally Posted by joe1l View Post
Well, its funny because i started off just trying to learn more for my own good, almost to point that I was hoping to prove the A9 to be the un-matched choice. Instead I learned that value always has a way of punishing you later. I think all the 8FG needed was a slightly larger screen and i probably would have bought it from day 1
I"m not trying to bash the A9 or Hitec but to say i'm happy with them would be less than genuine. If anything I wanted to finally give the data that I wish I had when I was trying to trouble shoot the issue. I tried sharing some of the data on Helifreak recently and was told that my findings were in-fact common sense and that i should of known that the Optima recievers needed 30 to 40% more current So its quite nice to hear that my findings were important... For me i'm just happy to have finally realized, that it was not just my "rotten luck" that this stuff was happening!


Well it is the desire to know more foronesown good that we have experienced some of the greatest discoveries.

Your findings may NOW seem like common sense to some but I'm pretty sure its not mentioned in any of Hitec's sales and marketingliterature or safety briefings in the manual.

I have passed theinfo on to a chumof mine who recently lost his BH Cobra pattern plane after he noticed his flight pack was getting low. the low battery warning is clearly not set high enough to cater for a few violent manoevres on landing approach. Plane was totalled. He will now run A123 packs
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Old Feb 14, 2011, 08:21 AM
A man with too many toys
United States
Joined Feb 2001
17,298 Posts
Does anyone know if the 8FG with the 12+2 channel and TM upgrade is the same as the 8FG Super?
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Old Feb 14, 2011, 01:15 PM
Sunday flyer
Gdansk, Poland
Joined Aug 2007
177 Posts
Quote:
Originally Posted by Reegor View Post
Telemetry requires more power, because the "receiver" now includes a transmitter. This is indeed not a surprise.
First of all, the average current consumption of the 2.4TX is some low hundreds of miliamps. Secondly, the current consumption due to airborne TX should not scale with the number of servos!

As the currents get bigger with more servos, I'd suspect something related to servo driving.

Michal
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Old Feb 14, 2011, 04:45 PM
Hitec/Multiplex USA
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Poway, California, United States
Joined Sep 2000
4,190 Posts
In response to the request that we better educating our users on how to prevent brownouts. This will be posted on our website shortly but I though I'd share it here first due to recent discussions.

Any comments or suggestion on how to better improve this are welcomed.

Mike.

What is a brownout?

This is what occurs if the voltage to the receiver drops below 3.5v. If this happens, control is lost until the voltage comes back above this threshold.

What can cause the voltage to drop to induce a brownout?

In electric models the receiver relies on the BEC (Battery Eliminator Circuit) to supply it power. These are typically rating from 1.5A – 3A @ 5V – 6V but some servos can actually draw more power than they can provide which can cause the voltage to sag below 3.5V causing a brownout. In most cases the BEC’s are overrated!

For Nitro or Gas powered models you would typically use a battery for power with or without this connected to the RX via a regulator. Again, we are relying on the batteries capability to supply the power needed for the servos. If the servos pull more power than the battery, connector, or voltage regulator can handle, the voltage can sag and cause a brownout. This is why it is always important to use batteries that can supply enough power to the servos for your specific application without having the voltage sag. The most common mistake is to buy on capacity alone. A 2000 - 2500mah AA size cell is a perfect example of a battery that works fine in low current draw applications like a transmitter, but can fall flat on its face when asked to power multiple high power digital servos. It’s always best to use at least a 6V (5 cell) pack or greater.

How can I prevent a brownout?

Hitec offers multiple ways that the user can guarantee that they always have sufficient power for the receiver so that they’ll never have to worry about or suffer a dreaded Brownout ever again.

1.) Hitec provides built in battery telemetry in our AFHSS system which allows the user to monitor their voltage input. The battery telemetry not only reads the voltage in real time but it stores the lowest voltage seen plus provides the ability to set a custom low voltage warning to give you any indication of a potential power problem or a low battery. The absolute best way to test if your battery is sufficient for you application is to activate all the control surfaces by quickly wiggling the sticks for a few seconds and then seeing how low the minimum voltage dropped to. If the drop was over one volt then you should probably not use that battery or regulator.

2.) SPC (Supplemental Power Connection.) This is a unique system only offered by Hitec that allows the user to power the receiver separately from the servos with up to 35V so even in the case that the servos pull down the BEC or battery voltage, the Rx still maintains a connection to the transmitter. In most cases this is only used in electric models and not nitro or gas since the user has the ability to choose the proper battery to use and in electric we are at the mercy of the mass produced ESC’s (Electronic Speed Control) BEC which may or may not be sufficient. The way to use this is to tap power of the connector that the battery plugs into (Up to 8S LiPo) and simply plug this connection into the SPC port. A fringe benefit of using the SPC is now the battery telemetry reads the voltage of the main flight battery and when utilizing the low voltage warning, the user can set the warning so that they know when their flight battery is getting low. This is nice because in many cases where you just use a timer, you may not fly as long as you could, or worse have your battery die unexpectedly.

So there you have it… Hitec’s AFHSS system with built in battery telemetry and the SPC port give the user the tools to protect themselves from ever suffering the dreaded brownout ever again!!!
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