Spektrum AR7000 worries

[bronzino]

Hi all,

Please humour me if this has already been covered

Over the last couple of weeks there have been 3 instances of club members losing there models. All state that there was a loss of control on the model, and it just fell from the sky.

They were all on Spektrum AR7000 RX, and all experienced flyers, so pilot error was unlikely.

One of the guys decided to send his back to horizon via the model shop he bought it from. The response from Horizon was alarming.

They state that all AR7000 RX should be used with 6V batteries, and they will not take any responsibilty for any damage caused etc from those using 4.8v.

But, what I find totally ridiculous is the fact that all early paperwork for the AR7000 makes no reference to using a 6V battery. Latter paperwork does list 6V is required, but then the picture on the same page, shows them binding on a Spektrum 4.8V battery ??!!?

The model shops in our area are now stating that they will not except any returns of Spektrum AR7000's that have been flown on 4.8v.

I've flown all my models on 4.8V and I have never had a problem, but now half the club are panicking and buying large quantities of 6V batts for there models.

It seems to me that Spektrum have changed there guidelines on what batteries to use, perhaps having several RX returned, but then have failed to make this change apparent to all the thousands of useres who are still flying on 4.8v.

What are your thoughts chaps ?????

[SRH990]

I think that Horizon are really saying that a low voltage spike in the electrics can cause the receiver to 'brown-out', especially with helicopters which can hit quite high current surges. With the early receivers if the voltage drops below 3.5v then the receiver 're-boots' which can take 10 seconds or so before you have control back, with latter receivers this problem is minimised as they don't do a full re-boot and connect again much quicker.

The route a lot of heli flyers have taken is to use regulated systems, either via a 2 cell lipo or 2 cell LiFe packs with a regulator to give a constant voltage output to the receiver & servos, another route is to use a 6V nicad or nimh pack. The difficulty we are now facing is that nicads are now outlawed in Europe and will be increasingly difficult to find and nimhs can drop their output voltage quite a lot under load, a 4 cell 2200mAh AA nimh pack sounds enough capacity wise but ask it to give 3A and it will wilt fast.

Personally I swapped to using 2 cell lipo receiver packs with regulators as soon as I swapped to 2.4ghz radio, this gives added security plus the servos receive a constant voltage so performance remains the same throughout a number of flights. Of course, if the regulator fails, as one of mine did a while ago, it still crashes! There are a number of servos already available and many on the way which will run straight off a 2 cell lipo pack, this gives faster servos with higher torque and removes a failure point, i.e. the regulator so are becoming more popular.

[sacko]

You can send the Rx off to Horizon and they re-flash it so Quick-Connect is enabled...


...and its free.

[Toolman]

As SteveH says, avoid AA cell sized packs.
If you are using 4 cell packs go for ones made up of SubC cells.

Tim.

[moyesboy]

I modified my power setup when I started using a 2 in 1 regulator.
The receiver runs directly off the 2 cell lipo, the servos and gyro run run off the regulator.

The AR7000 is ok up to 9v according to the spec.

What sort of models have been lost? The most common probs I've seen have been electric models running cheap ESC with their internal BEC. One large fixed wing had a problem at our field and that had a reproducable brown out as its lipo reg system wasn't up to the job. You could get the rx to reset by loading up the control surfaces.

I have good faith in my spektrum. I had one problems when the battery came loose on the plug on my knight (intermittent contact made it fail safe inverted) - and a couple of issues with static on my 450 (caused motor shut down but not loss of control, cured by earthing wires and silicone spray on the belt).

Interesting that spektrum are now advising 6v rx packs.
An Nimh pack with subC cells should be well up to the job. If you get one of the vapex instant ones then it will stay charged on the shelf as good as a lipo. Just check your servo specs and fit step downs where necessary.