Lower than expected servo amp draw.

[dahld]

Just thought I'd pass on some info that surprised me.

Kyle's been flyin' the Logo 700 a lot lately, as we continue to try new equipment on the machine, different set-ups, ESC's etc., in order to develop a broad experience base with the heli.

No brand names to be mentioned, but one ESC we were trying had no BEC. So we decided to power the on-board electronics with a small 2S Lipo battery (which traditionally we don't do, and would usually in the situation just run an external BEC).

At any rate, to find out how much power was being used per flight, we started with a freshly charged 2S pack, and then charged the battery after every flight, allowing us to build a record of how many MAH's were used each and every flight.

To my surprise, the average MAH used (after sampling about 20 flights), during an average (for Kyle) aggressive 3D four minute flight, was only 200mah per flight!

I though for sure the power consumption of the servos and radio on a 700 class machine being flown hard would be much more than that during a flight. And since we have traditionally used BEC's, I never had a way to determine the power used.

All this might be old news to some, but new to me. Interesting.

(-: Dave

[djamgils]

It depends a lot on the servos used and average consumption doesnt say all about peak amperage.
With 200mAh in 4 minutes you have 0.2*(60/4)=3A on average. How high it peaks???

If you look at the savox HV servos they really can pull 10A peaks.
http://www.helifreak.com/showthread.php?t=398142

[kevinww]

Dave, I see similar mah usage on my xxtreme running straight 2s lipo into Futaba brushless HV servos all around. Granted I don't bang the sticks like Kyle, but three 6.5 minute flights usually results in around 540-600mah going back into the RX pack.

[GimpyGolden]

Dave,
Since you guy's run a lot of setups with Jive you should look at a JLog2 logger.
Has a lot of info and easy to use.
Since it's sold in Germany I'm sure your Mikado buds could hook you up on getting one.

For more on it and where to purchase see the JLog sub forum.
http://www.helifreak.com/forumdisplay.php?f=257

[dahld]

@ djamgils,

Yea, I get the whole peak amp draw thing (-: ...which is why were using (although small in capacity), a 25C battery, so momentary 10 amp peaks are not an issue.

The 3 amp average is definitely not a bases for using say only a 3 amp capable BEC (-:

@ kevinww,

Your comment, "...I don't bang the sticks like Kyle..."

Me neither (-: I tried the same 2S deal on my XXtreme, and the results for me when I "sport fly" it for 9 minutes, on average are about 200-250 mah.

@ GimpyGolden,

"...JLog2 logger."

I've no doubt there are guys who have all this figured out long ago by the use of logged data. And that's good, as we all benefit from the data as it leaks into the community. But like I said, "All this might be old news to some, but new to me."

Funny thing is, for all the involvement Kyle and I have in the hobby, we've never owned or used any kind of data logging. I guess we're kind-of "old school" in that regard. Our version of data accumulation is: It either works in actual use over the long run, or it doesn't. Then we use what works (-:

(-: Dave

[rcmarty]

It can be quite a low draw depending on the pilot and flying style. Servo's also a factor

I think another factor to consider is the talent of the pilot, Kyle has great collective management and i'm sure that draws alot less when done right.

I'm working on my tic tocs right now , instead of catching and giving a little pop , i'm pulling an pushing with pitch.
Must draw alot more.

I flew my 700 nitro with reg 8717's on 2s 4000 lipo. I was about 300 mah on a 7 minute flight.

So it's quite plasuable to run a little 2s800 for weight condisderations ( that should throw a monkey wrench into the whole bec lipo debate .. lol ) as there would be a little if any weight penalty. Myself i like having a larger lipo with a capacity i can't comsume in a day for that huge safety buffer.

BUT ... lets not forget to charge that little bugger

Martin

[mahbouni]

Originally Posted by dahld

Just thought I'd pass on some info that surprised me.

Kyle's been flyin' the Logo 700 a lot lately, as we continue to try new equipment on the machine, different set-ups, ESC's etc., in order to develop a broad experience base with the heli.

No brand names to be mentioned, but one ESC we were trying had no BEC. So we decided to power the on-board electronics with a small 2S Lipo battery (which traditionally we don't do, and would usually in the situation just run an external BEC).

At any rate, to find out how much power was being used per flight, we started with a freshly charged 2S pack, and then charged the battery after every flight, allowing us to build a record of how many MAH's were used each and every flight.

To my surprise, the average MAH used (after sampling about 20 flights), during an average (for Kyle) aggressive 3D four minute flight, was only 200mah per flight!

I though for sure the power consumption of the servos and radio on a 700 class machine being flown hard would be much more than that during a flight. And since we have traditionally used BEC's, I never had a way to determine the power used.

All this might be old news to some, but new to me. Interesting.

(-: Dave

If Kyle is using 200mAh in 4 mins then that would be 3000mAh (200 x 60 / 4) in 1 hour. That means he's using an everage of 3Ah per hour, so he's drawing an average of 3A. This is well within the 5A continuous rating of a Jive BEC, but then you wouldn't want to be pushing it right to the very limit. The Jive BEC can handle 15A peaks so I would assume Kyle's peaks are also within that limit.

[rablett]

I did extensive servo current logging last year on 2 admitedly smaller FBL helis, both sport aerobatic flown. The 2 helis were a Protos and Logo 400SE. After hours of actual flight testing, I never exceeded 0.5 amps. Considering a properly set up FBL heli, none of the servos should ever reach their travel limits, which is when amperage would logically peak and likely go much, much higher. My results were, like yours, much lower than I expected.

[el guapo]

i use a 1100mah 2S life pack on my logo 600. with BLS451s, i use 80mA a flight.