Rbart

I dont think you understand my idea.. TWO seperate power circuits.. one to maintain the reciever, and one to power your servos, refridgerator, toaster, particle transporter etc...
I dont mean two packs in series... or parallel..

Your solution is the ONLY solution as things stand.. I was talking/dreaming about an improvement to the situation.
Actually, it would not be all that difficult to build the AR7000 (or any other DSM-2 reciever) with a jumper.. that would give you the choice of a single pack powering everything or two packs, one to power the receiver and one to power the servos.

jaka

Hi!
Been using the DX-7 system and small 4,8V 1000mAh Nickelmetall hydride battery this summer and fall in several Q-500 pylonracing competitions without any problems what so ever. Won 3 races of 4 with it!

Regards!
Jan K
Sweden

goirish

I have seen Sanyo 5 cell 4.8v 2700MaH. Would this be a good battery for the DX7. Only cost about 23.00.

RCKen

My Feedback: (9)

If it's a 5 cell battery then it should be 6v. But yes, this would be a good battery for the radio.

Ken

-pkh-

My Feedback: (2)

I use a 2000mAh 5-cell pack made up of 4/5A cells in my Twist 150, since I have 4 high torque servos in it. The Voltwatch I installed on it shows the voltage varies quite a bit as I move all the servos at the same time, pretty much all the LEDs light up, even the one's below the safe level. I think putting a decent size capacitor on the receiver's power pins would probably filter most of this out, but haven't tried it yet.

I get my packs custom made at: http://www.cheapbatterypacks.com

My latest set of packs are made out of the Elite 2000 4/5A cells (see below). I think a 5-cell pack is $22.50, and a 4-cell pack is $18.00.

goirish

Yes you are right. I looked at it wrong--they do have a Sanyo 4.8v that is also 2700mah NiMH. Cost approx 18.00 either flat pack or hump back

goirish

Hopefully this is a picture of that pack I was talking about
Nope didn't work made by onlybatterypacks.com

BillS

Gr-r-r!

Designed for hard failure on low voltage spike and not likely to stand the test of time.

Bill

B.L.E.

I think that a lot of the TOC giant scale guys are doing exactly that, a battery that powers only the reciever and a separate battey that powers the servos, usually a lithium ion battery pack that's regulated to 6 volts. Even if the servos "dim the lights" from a high load, the radio reciever never knows it.

Redback

I did some current measurements on DX7 gear a couple of weeks ago using a rig to put load on servos.

The results showed the AR7000 receiver drew 54.9mA compared to 23.41mA for a JR RS10DS (Synth PCM dual conversion)

The readings for the servos were quite different however, with the DS821s taking less current (40mA) to hold against an aplpied load than a JR539 (150mA).

Wasn't able to measure the transient current with the meters I had. Set up was intended as far as possible to compare like with like.

BTW very happy with my DX7 so far. Also bought a module for my JR388S but don't see me using it right now as the DX7 is so good.

Terry

CGRetired

My Feedback: (1)

Wouldn't everybody agree that if you are experiencing a problem, or suspect that you are, or are paranoid about it, then use a 5 cell pack of sufficient current to do the job. They are certainly cheap enough, much less than replacing an aircraft. If you are concerned about the speed of the servo's over the 4 cell packs, then use some exponential to soften the response.

CGr

MasterX

My Feedback: (6)

Hello everyone. I have done a lot of tests on this low voltage. What I found was on a 4.8 volt pack with a full charge will be ok for maybe 2 flights. when the voltage is near or below 4.8 volts and you crank up your servos you could see a loss of around 1 volt. This gets you very close the danger zone of 3.5 volts and below. Once the Spektrum receiver sees 3.5 volts the receiver will reboot. When your system reboots it take about 2-3 seconds.. Now if you are flying around on a 6 volt Nima or NiCad pack you will be good for 4-5 flights. However, if you are running digital servos and on a 50cc machine I suggest you run Lion packs. This will stop all issues with the low voltage.

Personally I am running 2 2600 lion packs in my 50cc'er. When I tested this I never dropped down below 6 volts with even pushing my control surfaces.

Bottom line is that there is an issue with the voltage.. The 2.4 system is nothing like the 72 system. On 72Mhz you can run your receiver on 1 volt. Your servos will not move much but, your system will not reboot.

This is all that I have now..

I will continue to test and test. I do not want to have any issues with the voltage.

Thanks

Flypaper 2

I'm running the stock DX7 batt. in a 1/4 scale Starlett with no problems. 4 flights and it gets to 5.2 volts and I recharge. I consider it's dead when it reads 4.8 volts. Don't know why people yell and jump up and down when they prang their plane trying to fly on a dead batt. Guess they don't know what an ESV is.

BillS

My wife purchases several electrical things each year. When they don't work as expected she votes with her pocketbook. She doesn't give a happy damn about learning about electronics or programing.

Bill

B.L.E.

Exponential is not exactly the same as slow servos. Fast servos go exactly where the control sticks command them to go just like slow servos do. It's just that you can move the sticks faster before the servos can't keep up with them.
Slow servos do not make a plane easier to fly, in fact, they do just the opposite. With fast servos, your plane feels more connected to the sticks, making the plane easier to fly. That's why pattern, heli, and 3-D flyers pay premium prices for super fast servos.