6V Nimh and 2.4 Ghz Spekrum reciever?

[JoeAirPort]

	Quote: Originally Posted by bmoney69
	is your 50cc yak on 2.4?

Whups, I missed this question. Yes it is !

It's a single Elite 2000 on an AR7000. 7955's all around except a 5985 on throttle. After 5 flights, the battery was still pretty strong.

[wildhare]

	Quote: Originally Posted by cjcyclesrc
	Keep in mind the low voltage reset problem was fixed on the Spektrum receivers. So it's now no different than a 72 mhz receivers.

Not true, it is inherent in the design of the internal microprocessor. What they did fix was the 1-3 second waiting period to recover from the reset, now it almost instantly restarts after a failure. But if the voltage is still low it will keep happening.

A plane with that complement can be expected to suck up as much as 15 amps in a hard snap. The testing that shows 6 amps was (I believe) without a load on the surfaces. Place a heavy aerodynamic load on it and watch the lights go out.

I did some testing over a year ago with an Eagle tree recorder in a 100cc Giles with servo set up not unlike yours. I had only 1 servo on the rudder, other than that as I recall it was pretty close. If you will look at the attached graph you will note that it had a peak draw of 11.5 amps in a hard snap. This was with a single A123 pack and a conventional switch with 2 connectors into the receiver. I have since figured out that it probably would have drawn a bit more current had I been using better connections into the receiver and dual packs.

You should be sure your packs will hold voltage up above 4.5 volts minimum when supplying 12 amps (combined) for at least a few seconds to be sure there will be no resets.

TF

[cjcyclesrc]

Tom thanks for clarifying the fact that I left the letter S out of my post. My mistake.
Keep in mind the slow voltage reset problem was fixed on the Spektrum receivers. So it's now no different than a 72 mhz receivers.


You are correct the 6amps was under no flight load and no binding. I was just moving the sticks as fast as I could.

[bmoney69]

ok, good info....soo asuming i'm not getting much loss thru the wire or connectors and i have no switches i would say that 12 amps is going to load my packs at about 1.5v at most....should be fine consider i have duel packs with EC3 connectors directly into the module.

[cjcyclesrc]

http://www.flyinggiants.com/forums/f...t-feature.html

Here is a little more info on the Spektrum Update.

[JoeAirPort]

Good info.

[wildhare]

	Quote: Originally Posted by cjcyclesrc
	Tom thanks for clarifying the fact that I left the letter S out of my post. My mistake. Keep in mind the slow voltage reset problem was fixed on the Spektrum receivers. So it's now no different than a 72 mhz receivers. You are correct the 6amps was under no flight load and no binding. I was just moving the sticks as fast as I could.

Hah! That's funny. Drop 1 letter and it completely changed your meaning and was still intelligible and gramatically correct.

I feel like i'm becoming the hall monitor here.

TF

[cjcyclesrc]

	Quote: Originally Posted by wildhare
	Hah! That's funny. Drop 1 letter and it completely changed your meaning and was still intelligible and gramatically correct. I feel like i'm becoming the hall monitor here. TF

I don't think you would want to be a hall monitor at the school I am from.

[T-ster]

I have the XPS system with the upgraded receiver which gives me a orange light if the voltage drops below 4.4 volts. On my 1/3 scale planes (2 of them) with Airtronics 94357's and 94358's (old school analog servos) and 2-1650 NiMH's, I could get a low voltage light by rapidly moving the sticks for 30 seconds. With only 1 of the 1650 packs switched on I could get an orange light in 1-2 seconds, which really scared me. On a .60 size plane with 1 battery, I could get a low voltage light within 30 seconds on it.

I've already had one lockout which resulted in a rekit of a 1/4 scale plane, so didn't want to risk another plane. On the three planes listed above I had been flying them for over a year with no problems, but once I got an upgraded receiver that shows the orange light I quit risking it. Although there is still some room between the warning voltage and the reboot voltage, it was not worth the risk to me. I changed to the A123's and cannot get an orange light no matter what.

Just my $.02.

[cjcyclesrc]

T-ster,
It's good to hear you fixed your problem before you lost anymore planes.

If you had The Elite HR1650AAU NiMH packs, they have an Internal Impeadance of 25 mOhms. That would make them one of the worst Nimh's at holding volatge. Just for comparison The Sanyo HR-1950 FAUP is rated at 4 mOhms which is equal to that of a Sub C Nicad.

Do you fly at the grapevine field?

[T-ster]

I had the Sanyo cells, but had the issue.

No, I fly at a renegade field in Allen at Exchange Parkway, just East of 75. I have flown at Grapevine before with my heli's, but that has been awhile.

[bmoney69]

t-ster.....4 or 5 cell batts?

[JoeAirPort]

T-ster, do you know what exact Sanyo cell it was?

In general you need to use only the low impedance/high discharge NiMh cells. They are out there, you just need to know which ones they are. The 1950 FAUP and Elite 2000 cells are very good. I always use a single 5-cell NiMh for rx and Elite 1500 4-cell for ignition. I've never had battery issues with those packs on 50cc 3D aerobats with all high torque servos. They are setup on Spectrum.

[cjcyclesrc]

	Quote: Originally Posted by T-ster
	I had the Sanyo cells, but had the issue. No, I fly at a renegade field in Allen at Exchange Parkway, just East of 75. I have flown at Grapevine before with my heli's, but that has been awhile.

We have probably bumped into each other. I used to fly Heli's behind Mike's a couple years ago and planes a couple times at Grapevine when I lived in Dallas.

[T-ster]

I was using 5 cell packs. They are the: NiMH Sanyo 6V HR-AAU 1650mAh. That sounds like it may be the type of cell that is questionable..... That would be surprising as the company I purchased them from are extremely knowledgable and seem to be a very respectable business.

No other receiver I know of has a low voltage light, so other 2.4 Ghz systems may be running on the edge and you wouldn't know it. I had been flying those type of batteries for several years now and been ok until one time. While I don't know it was the battery (after the crash it still had over 1,000 mah left in it) once I started seeing the low voltage light it scared me enough to want to eliminate that as a possible failure point.

cjcyclesrc, I used to fly at the North Dallas club for years, but once they moved north adjacent to Denton, the travel time was an issue.