asaad_civic99

Hi,

I have a new spektrum DX7 on order. I have read horror stories of carshed models due to this brownout condition which happens when the voltage of AR7000 receiver drops below 3.5V due to sudden load on one or more servos, reulting the receiever to reset. I know that the new AR7000 have an instatnt restart. But assuming that my AR7000 is from old stock, will a voltage regulator reduce the chance of a brownout? or maybe using a separate battery for the receiver? Any recommended brands?

fizzwater2

My Feedback: (61)

I've been running 6V batteries (5 cell NiCd or NiMh) with great luck, no problems at all.

If you're running a bunch of digital (high current drain) servos in a big plane, etc, make sure your battery / power supply system is up to the task. I fly mostly racing planes with analog servos and have had no troubles at all with little NiCd packs, 300-350 mah 5 cell.

A regulator isn't magic - you have to have a higher battery voltage to start with, then it will regulate down. Some guys are using 2-cell LiPo batteries (7.4V nominal) with 5V or 6V regulators, but again, you have to make sure your battery / regulator combo is up to the task.

Use a good quality switch, too. Skinny wires and/or cheap switches can lead to voltage drop under high current loads.

BuschBarber

My Feedback: (2)

Do yourself a favor and buy a Hangar 9 Current Meter or use a Wattmeter, if you have electric powered models. You can measure the Current Draw of each servo, under simulated maximum load, by connecting it between a servo and the Rx, or you can measure the Current Draw of the entire system by connecting it between the Battery and the Rx. If you put all the servos under load to simulate extreme conditions, you can also measure the Voltage Drop, if any.

Now that you know what the maximum load is on your system, make sure you have a battery that can handle that load.

PacificNWSkyPilot

My Feedback: (19)

asaad,

If you are using a standard system on a standard mid-sized plane or less, then simply make sure you are using a good 6V battery pack with a nice high mAh rating. That's the best insurance. The stories you read are from the tiniest, tiniest fraction of the flying population out there. The truth is, most of us have never had the first issue with it, not even using 4.8 V battery packs.

If you're using a larger system with high-draw servos, then yes, you can use a regulator. Just don't be spooked by the stories. Try and find anybody you know who has had an issue, you'll likely not be able to find anybody at all.

I simply buy high-rated mAh packs from Radical RC.com, like a 2600 mAh 6-Volt pack. Then I fly it and forget about it. And I make sure I take good care of my batteries.

Fizwater made an excellent point too. Use a really good grade of switch, a crappy switch or a bad switch can kill a plane faster than anything.

You'll be fine!

asaad_civic99

Thanks for the advise guys,

My plane is 1.2 nitro powered aerobatic plane. 8 servos:
1 futaba 3003 for the throttle
2 futaba 3003 for the flaps
2 futaba S3152 digital Hi torque for the ailerons
3 DS821 Hi torque servos (1 for the rudder & 2 for the elevator)

What battery and switch do you recommend?

BuschBarber

My Feedback: (2)

I use Zippy 2cell 2500mah LiPos for under $30. The charge lasts forever and a recharge takes less than an hour. I use a $19 5v or 6v regulator. You could also go with A123 or Eneloop batteries. My NiCad and NiMh batteries go in the dumpster.

PacificNWSkyPilot

My Feedback: (19)

I'll leave that to somebody else, I don't know Futaba Servos at all.

I know the DS821's are not bad at all, I have them in several planes.

I throw LiPos in the dumpster, and I don't use a regulator unless the system calls for it.. Anything extra is another thing to break down, and LiPos are too delicate and touchy. NiCADs and NiMh are solid and dependable, and can take fast charging, much hardier.

electricpete

Can someone give me some differences between, the reboot time of an old and new AR7000, as I recently had an incident were I spiraled in from about 200 ft with a simple 4 servo system and a good 1400maHr nicad.

Peter

Zeeb

My Feedback: (41)

Initial link time is 2 to 5 seconds.

Re-link time after a power brownout on rx's with the original firmware is that same 2 to 5 seconds. Re-link time on rx's with the Quick Connect firmware is less than 1/2 second.

jmohn

First make sure you have the "quick connect" firmware on your receivers. That will reduce the "brown out" time like Zeeb said above. Next, I would recommend using either a good receiver pack (NiMH or Lipo) or use a UBEC like Castle sells that can provide 10 amps off anything from a 2S to 6S LiPo pack. I have been using these with 3S packs on all my planes since the "brown out" stuff started and haven't had one issue since, even using old receivers with the older firmware.

Just don't use the ESC BEC unless your using less than a 4S pack.


Jeff

electricpete

I am interested in the brown out condiion as I recently had a complete radio failure with a ar7000, 1400maHr battery, 4 futaba 4148 servos in a simple Arising star trainer flying at about 200 ft, When entering a slight 90 degree turn. I spiraled in. The battery was checked by discharging it. It had plenty of power left. The rx was sent to Horizon, no fault found. The RF module was also sent to Horzon, no fault found. I was on Buddy box with an experienced instructor, who was unable to regain control.

What is the difference in reboot time between old and new AR7000?

Peter

BuschBarber

My Feedback: (2)

This was posted just above in this thread:

Initial link time is 2 to 5 seconds.

Re-link time after a power brownout on rx's with the original firmware is that same 2 to 5 seconds. Re-link time on rx's with the Quick Connect firmware is less than 1/2 second.


As I understand it, a Brownout can occur when the Current Draw on the Rx causes a Voltage Drop that forces the Rx to Reboot. Just Cycling the Battery or Checking the Voltage, after the incident, is all well and proper, but it does not tell you the whole story about whether or not you Could or Had a Brownout.

You need to manually put all you servos under maximum load and at the same time, measure the Current Draw on the Rx and the Voltage throughout the test. Your battery can be fine and still suffer a Fatal Voltage Drop if enough load is put on the battery. That is why it is recommended to choose a battery that has more than enough capacity for your system. or that you use a 5cell/6v pack with more than enough capacity, if you can.