Futaba HPS-CB700 just arrived

[norbyx]

So I finally got the Futaba CB-700 in my hands today, and let me say that I am quite pleased with this servo.
First of is the speed and deadband, it is the lowest I have ever tested with my tester, 1usec. and I can hear it even at lower than that but the tester doesn't show a lower number.
Second is speed, this thing is faster than a blink of an eye. I have never had anything like this.
And last is the torque, it is just there, and never ends, at 680oz/in is just amazing.
Best of all it doesn't need a bec.... so it connects directly to the receiver.




Here are the videos of the testing:
https://i.imgur.com/gegKytU.mp4
https://i.imgur.com/EXVoHoI.mp4

[Szczerba]

What are the features that make it not need a bec?

[norbyx]

Originally Posted by Szczerba

What are the features that make it not need a bec?

Well from what I could find out on the internet the amp draw is lower than 3 amps at full load so no need for a bec there. The motor is brushless...

[Greatscott]

That thing is a beast!

What truck is it going in, and what ESC?

[norbyx]

Originally Posted by Greatscott

That thing is a beast!

What truck is it going in, and what ESC?

Well it is going (actually it is already installed as you can see in the video) into my TRX4 Sport, that weighs about 12 pounds (it has every possible upgrade in the market) It already fried a 20kg servo (those cheap ones from amazon) so I decided that with that weight I needed something with a lot of torque.
ESC is the hobbywing axe.

[Szczerba]

Originally Posted by norbyx

Well from what I could find out on the internet the amp draw is lower than 3 amps at full load so no need for a bec there. The motor is brushless...

Yah, good point. I was just curious if it was stated. I looked at a few websites earlier as well.

[whitrzac]

Why this vs the hps-a700 at 1000oz? The extra speed really isn't needed in a crawler.

[norbyx]

Originally Posted by whitrzac

Why this vs the hps-a700 at 1000oz? The extra speed really isn't needed in a crawler.

Well that is a good question, even though I didn't need the extra speed, I doubt I needed the extra torque ether, so I thought that I might use some more speed, sometimes to slide in a very steep down hill without using the throttle
or some other thing. Anyway almost 700oz/in is plenty torque, why go to 1000? And even though my car is all metal, i think that 1000oz might break something.

[JatoTheRipper]

$250!!!

It better come with toilet paper!

Not needing a POS BEC is a great thing though.

[svt923]

Originally Posted by norbyx

Well from what I could find out on the internet the amp draw is lower than 3 amps at full load so no need for a bec there. The motor is brushless...

The video I saw that Futaba put out shows it pulling under 3A at a normal load, they don't show the draw at full stall which should be substantially higher (and frequently encountered on a crawler).

Also based on the documentation included with the servo, it appears Futaba does not recommend you run it off the internal BEC of an ESC due to the amps the servo can draw. I would not take this to mean the servo does not require an external BEC.

[norbyx]

https://youtu.be/7pgCBavvRJU

There you can see it work under load and the amp draw is very low.


Inviato dal mio SM-N9600 utilizzando Tapatalk

[norbyx]

Also I think that the included instructions are generic.... As you can see in the back of the box there is No need for bec or battery.

Inviato dal mio SM-N9600 utilizzando Tapatalk

[svt923]

Originally Posted by norbyx

https://youtu.be/7pgCBavvRJU

There you can see it work under load and the amp draw is very low.

Yes, that is under load but since I can't read Japanese, I don't know how much weight the servo is actually moving. I would guess is that is nowhere close to enough weight to get a true understanding of the amp draw at stall like what would occur when getting bound up in the rocks.

A Savox 2290 is brushless and makes similar torque and it's stall amp draw is about 7.5 amps at 6V. I believe the Futaba is more efficient than the Savox but it would have to be 40-50% more efficient to get down to the levels where an internal BEC would be sufficient.

As for the wording on the box, I interpret it as meaning do not power it from dry cells or a BEC because those are not adequate power sources and direct battery power is recommended.

[whitrzac]

Junky savox servos are almost single handedly responsible for the BEC and 'glitch buster' market starting 10-15 years ago. Along with some of the other cheap china servos.


The 4-500oz servos of old were a lot more efficient than modern offerings, a lot more expensive too.

[JatoTheRipper]

Originally Posted by whitrzac

Junky savox servos are almost single handedly responsible for the BEC and 'glitch buster' market starting 10-15 years ago. Along with some of the other cheap china servos.


The 4-500oz servos of old were a lot more efficient than modern offerings, a lot more expensive too.

Interesting. I've always blamed Castle because their old ESCs were very popular, but they had terrible internal BEC's. That all changed with the Mamba X.

[norbyx]

Originally Posted by svt923

Yes, that is under load but since I can't read Japanese, I don't know how much weight the servo is actually moving. I would guess is that is nowhere close to enough weight to get a true understanding of the amp draw at stall like what would occur when getting bound up in the rocks.

A Savox 2290 is brushless and makes similar torque and it's stall amp draw is about 7.5 amps at 6V. I believe the Futaba is more efficient than the Savox but it would have to be 40-50% more efficient to get down to the levels where an internal BEC would be sufficient.

As for the wording on the box, I interpret it as meaning do not power it from dry cells or a BEC because those are not adequate power sources and direct battery power is recommended.

If you see the video the servo on the left draws up to 3.8 amps, the one on the right I can't seem to see anything over 2.2 so that is a lot of difference, I can't tell you the top amp draw of this servo since there are no reviews out there and my servo tester doesn't have enough power to make that test. It might not be 3 amps, maybe its more, maybe not. When someone else will be doing the testing we shall see. For now I will have it hooked up to my esc.

Inviato dal mio SM-N9600 utilizzando Tapatalk

[whitrzac]

Originally Posted by JatoTheRipper

Interesting. I've always blamed Castle because their old ESCs were very popular, but they had terrible internal BEC's. That all changed with the Mamba X.

The crappy BEC in the mmp also played a part, they both came out around the same time, even that will run a 94780 or futaba equivalent without issue.

The first mmp software would shut down the bec entirely if it was overdrawn too iirc. I know that a cheap JR servo+ gen1 spektrum + mmp was not a happy combo.

[JatoTheRipper]

Originally Posted by whitrzac

The crappy BEC in the mmp also played a part, they both came out around the same time, even that will run a 94780 or futaba equivalent without issue.

The first mmp software would shut down the bec entirely if it was overdrawn too iirc. I know that a cheap JR servo+ gen1 spektrum + mmp was not a happy combo.

I was thinking of the Sidewinder that also came stock in most of the Axial RTR's of the time. I hated that ESC because it would brown out if your breathed on it.