Align DS610 servos = high current

[worldofmaya]

I didn't wanna scare anyone... but I know that a few fried their BECs because of empty puffer batteries (but I didn't hear about capacitors by now) which where too big to just let a BEC charge them.
I searched a little bit and got some theoretical infos. There's a time constant in which a capacitor loads / unloads. After 0.69 * timecontant (can't find the symbol here, it's a greek "tau") it is charged by 50%, and after 5 * timecontant it is fully charged. You could calculate this by using the formula t = 5 * timecontant = 5 * R * C (R = resistance, C = capacity). By the way it's a e - function which means there's quit a lot of current at the beginning. A image of this looks like this graph -> http://www.elektronik-kompendium.de/...m/02053011.gif
That should be the same as what you should see on a oscilloscope! Would be interesting what you found out with your test!
At least it's worth mentioning before someone uses a capacitors which is too big / too much charging current!
-klaus

[BruceW]

That's a good point. Sometimes bigger is not better.

[worldofmaya]

Originally Posted by BruceW

That's a good point. Sometimes bigger is not better.

Yes... really depends on the application
-klaus

[MrMel]

Just a FYI, there is a application built for this, Fromeco has a product called DC-Up, not only is it capacitors, but also a display showing current and lowest voltage.

I flew with that, with 3.5amps (!) BEC's, on my VBar 90 sized machines (!!), and it never dipped in voltage more then 0.1-0.2v.

So perhaps, "stirring" on the bench, with no airflow actually is alot harder then any real life flight, well, Im not into crack-flights, that would perhaps what you need to overload it...

[worldofmaya]

Just found it -> http://www.fromeco.org/Products/05FRCDCUP/Default.aspx
Interesting... 1,66f when taking 6V as base (they wrote operating voltage) this should be aroound 2,76mAh of energy. It has 25g, my 4-cell NiMH buffer has 650mAh and weights 68g... a 180mAh 4-cell has 12g.
I think this part is too heavy for buffering spikes and too small to over-bridge a BEC shutdown. But of course a good solution for bigger helis.
-Klaus

[BruceW]

I might give the DC-Up a try. Nothing like accessorizing.

On another note, when I ran the homemade voltage stabilizer on my setup with the CCBEC, the BEC got warm (not blazing hot) with minimal servo movement. I ran it for about 5 minutes with slow stick stirring and tried to simulate how I would fly the plane. When I did this in the past with the BLS451s it stayed at ambient. Looks like these servos pull a decent load even when moving slow and no load. I didn't get any brownouts but still not comfortable running the CCBEC with these servos.

[NTM]

Oh yes, I forgot to mention Bruce, I'm jealous as hell that you've got that 70" slick !
Looks like the perfect plane for a 6s 5000mah.
What are you going with for a motor ?

I'm currently putting together a 68" 540 edge (with 610 servos, lol ! ), with a scorpion 4035-380 on a 6s 5000mah.

Back on topic, I'd like to hear more about these small "buffer packs".
How often do they have to be charged, if at all ?

Regards,
Nathan

[BruceW]

Nathan,

I can't wait to get it - should ship in Aug. Been flying an Extreme Flight Edge540 (47") but ready to get a bigger plane. Going with the Scorpion 4025-12 (440KV) rated at 2000W. The plane should come in about 8lbs so that's 250W/lb which should make it very nimble with ballistic climb out power. Also going with the Scorpion ESC 120A (new ones will be in stock next week with the updated firmware) but will try it on the Logo500 to test out the new governor. This will be my first 3DHS plane so I'm really excited about it.

Wow - that 4035 in the 68" Edge is going to be ballistic!!! What size prop you going to run?

Also going with the fantasy blue scheme and getting the Red Bull vinyl package.

Even though these Align servos are power hungry I think they will take less in a plane than in a helicopter. If the WR Super-mini shows good promise about keeping the voltage up I might try them in the Logo.

[NTM]

That red bull scheme is going to be hot !
I'm trying to talk myself into their 57" sukhoi in that color scheme.

I'm going to end up with either a 20x8, 19x8 or 18x10 prop, I've got quite an assortment to try out.
7-8 kg of thrust should be do-able according to calcs, and weight should be roughly 4 kg all up.
Going to run a 5a WR bec though, and that's one of the reasons I'm curious about the little nimh buffer packs.
I think your right though, planks should be easier on the bec's than a heli is.

Regards,
Nathan

[worldofmaya]

Hi!
About the buffer packs... they should be small, around 10% of the current you're awaiting. I have a 650mAh 4-cell which could be used for up to 5.6V. I hardly ever charge my buffer battery. I do some cycles from time to time so it doesn't die. I do use it to setup my VBar, so I don't need to connect my 12s to get some power from my UBec.
You'll see if you use such a small battery that it will be the power source at the beginning. A NiMH has something around 6V end-voltage when charging. With some load it drops pretty fast and the BEC overtakes as a power source. As soon as the voltage drops the buffer will be used too and therefor the load is split.
But as written above you really have to take care if you're using bigger packs. They really draw a lot of current if they're empty and a BEC is switched on! This isn't a problem if the buffer is small and of course if it's a small buffer you don't really need to charge it. Just cycle it so it stays "fresh". If you only charge a buffer pack, you'll see that you only need to charge a few mAh and it's full!

Taking a capacitor instead is a good idea for small spikes and the Spektrum receiver, but a small buffer batter really helps if a BEC or the main battery fails.

By the way great planes! I too think of getting one again would be a nice variety to helicopter flying...
-klaus

[BruceW]

The only thing that concerns me about a buffer pack is that you need to maintain the voltage (or capacity) so that its close to your desired voltage of the BEC otherwise you'll be putting too much load on the BEC as you mentioned. Is it possible that you could overcharge it as well if you just keep using it without an inbetween discharge?

[worldofmaya]

Overcharging is a issue as soon as you hold it on a high level like 6V. With 6V a 5-cell would be better. But I think about getting a Jive instead of my Phoenix and than I wouldn't (or at least only a really small one) use a buffer anymore.
-klaus

[MrMel]

Jive manual states if Im not mistaking
5.6v or lower = 4cell
>5.6v use 5cell.

[worldofmaya]

You're right... 4-cell up to 5.6V. Using a Jive it would be enough to have a small 180mAh 4-cell which weights around 12g. One of the points why I wanna buy a Jive. My Logo would loose 160g with the benefit of a better BEC and Governor!
-klaus

[BruceW]

I ran the WR Super-mini at 6V with the 4x Align DS610 with massive stick stirring (no load) and did not see any drop in voltage! It stayed at exactly 6V. This is with both leads from the BEC plugged into the RX. When I had just one lead it would drop to 5.9V but that is nothing. It also looks like running the capacitor makes no difference with the Super-mini - its that good.

Wow, I'm just amazed at how well this BEC performs and it was only slightly warm. Its also only slightly bigger than the CCBEC but a little heavier.

Hmmm, now I'm thinking about trying them on the Logo since they are faster and a little more torque than the BLS451.

[rotorstart]

Hey BruceW and all,

I'm also using the Align DS610 on my collective for the Trex-600ESP. With one of the servos, when I spin the wheel all the way toward one end, there's a grinding feel. I'm not sure if this is normal or not. I recently had a crash with the heli and I'm not sure if this existed before the crash.

Can you tell me if you have this issue? Thanks in advance.

[NTM]

Originally Posted by rotorstart

Hey BruceW and all,

I'm also using the Align DS610 on my collective for the Trex-600ESP. With one of the servos, when I spin the wheel all the way toward one end, there's a grinding feel. I'm not sure if this is normal or not. I recently had a crash with the heli and I'm not sure if this existed before the crash.

Can you tell me if you have this issue? Thanks in advance.

You recently crashed and now you noticed a grinding in the servo ?
That seems pretty straight forward, open it up and check for damage or debris.

[hawkins221]

[HugoCraft]

Okay I'm new to having something take a lipo larger than a 4s and wondering how to do a trex 600e. I'm using a DX7 and I want to use my JR770 3D gyro w/ DS8900G which you all know is a 4.8v servo. So which servos should I get for the swash and what RX????

It would be neat to use the AR7100 7-Channel DSM2 Heli Receiver (SPMAR7100) so I can use that tail servo at 5.2v and then I can plug a 2s directly into the RX using HV swash servos. But which HV swash servos????

Or should I just get 6V servos and use a BEC off the the flightpack with a step down on the tail. But which BEC????? If I did use a BEC then I could use extra AR6200 that I have.

[FlyBarlesss]

Ya the WR Super-mini is a great BEC, i've been using one for a wial now and it's always rock solid !!!