Isolated battery for the retract or use the airborne packs for the retract ?

[BryanB]

Does Etienne or anybody else on this side of the pond carry the Emcotec OCP units? I'd take at least two or three right away.

[SoarHead]

Another question I can't seem to find the answer to is what does the built in "over-current" or "temperature" protection on modern Hitec, MKS, Spektrum, etc. servos actually do?

Bryan, Hitec tries to keep their servo overload protection a secret or at least that's the way it seems because the only thing I could find on it was from a Hitec servo programmer manual. Here is what they say.

"OLP Rate (Overload Protection Rate) (For HS-7XXX Digital servo series and HS-5055, 5056, 5065, 5082 and 5085MG Digital servo only) This function allows you to set the amount of torque reduction to protect the motor from stress that would cause it to burn-up. What is Overload Protection Rate?If the servo is overloaded, and can't reach the destination position as it would be directed to do, the overload protection system is activated. In this case, the servo amp will reduce its output power by the value you set from the maximum power. Increasing the overload protection rate is the same as limiting the output power, or torque.That is, if you select a value of 10% by adjusting the knob, the servo amp will reduce the power by 10% and output only 90% of the maximum torque in overloaded situation.You can set the value between 10% and 50%. If you select "Off" in this mode, overload protection will not be activated, and the servo will always produce maximum torque. When the overload is released, the protection mode is terminated and the servo will work normally."

I like your idea of the inline fuse so much I'm installing one in my LG circuit.

See you in April at AP.

[SoarHead]

Does Etienne or anybody else on this side of the pond carry the Emcotec OCP units? I'd take at least two or three right away.

You might try Esprit. I know that they carry a bunch of Emcotec products. If they don't have it maybe they can order one for you. If Z wants you to order more than one let me know I'm good for one.

[SoarHead]

Just heard back from Z. He can order them.

[Hoot]

I sent an email to esprit model (ZB answered my email) about the Emcotec servo overload device ( He said he will order them). I ordered two.
if you want one, I suggest you call esprit model before he puts the order in.

[BryanB]

I sent an email to esprit model (ZB answered my email) about the Emcotec servo overload device ( He said he will order them). I ordered two.
if you want one, I suggest you call esprit model before he puts the order in.

Sounds good. I'll give him a call and ask him to get an extra 3-4 units in stock..

[DanR]

The phone number in post number 20 is NOT for Esprit Models (it's for something in Texas).

The number for Esprit is 321-729-4287.

I just called and ordered one, the woman said it would be $30 plus shipping.

Dan

[Hoot]

Sorry about the wrong phone number for Esprit Model. Their number is 321-729-4287

[BryanB]

Yep, they said they had 5 in stock so I grabbed 3 of them..

[Hoot]

Bryan,
I hope I get the other two !

[Rjtw]

I haven't used that particular Emcotec product, but I've noticed it and wouldn't hesitate to try it. I think very highly of Emcotec engineering and have a number of their other products.

Back on topic, if you happen to run Sbus, here is another solution that avoids the entire issue of over-current, separate batteries, etc. It's called the "PWM Expander", available from https://shop.tje.dk/catalog/. I've been running this on a 1/3 Arcus for a couple of years and it's been working flawlessly: https://www.rcgroups.com/forums/show...0&postcount=77

Ultimately, no matter what you do, you should have telemetry so you can monitor your unregulated pack voltage(s) and set an alarm if it falls too low. There are even current monitors available if you want to go crazy. I actually monitor not only pack voltage, but remaining pack capacity, both with alarms, so I'll know when it's time to land even if there is a stalled servo or other unexpected problem.

[BryanB]

This is a question for SteveP.
I've been reading up on PowerBox systems and came across this in the manual for the Champion SRS.

In the highlighted section, does this mean that if your gear servo jams/shorts out the PB will automatically cut it's power?

[Steve P]

Hi. You’ve asked multiple questions. It’s important to remember a jam and a short are not necessarily the same thing. It is very possible to have a servo impropriety center and create a current drain over a period of time that kills a system — or partially jam and drain more quickly still without shorting per se. Of course a severe jam will drain, quickly overheat the servo, melt the wire and servo and only then potentially cause a “short” as the wire melds together or servo goes to $#!+.

Of course, shorts can happen anytime from wiire wear, getting caught in a mechanism, etc.

There are two outputs on the left side of a Champion to drive the PowerBus wiring system. Similar to what Rtjw points out above. PowerBus does what you have highlighted.

The PowerBus line is here... https://www.powerbox-systems.com/en/...cessories.html Click on one of the PowerBus products and you will see a full explanation of the system.

Hope this helps.

[tewatson]

I can attest to the PowerBox (PowerBus hub) isolation functionality from first-hand experience. During the shakedown flights for my then-new (and now departed) JS-1, a screw backed out of the landing gear hub/frame. It was eventually enough to prevent the gear from fully retracting, because the screw would jam hard against the bottom edge of the open gear door. On the 20-30 minute flight where it eventually jammed up, the lighting and contrast conditions made it hard to see the gear was still partially extended, so I didn't notice until setting up to land. The gear extended just fine and I never had any battery drain problems or low voltage alerts, and nothing was toasted or even warm.

My understanding is the PowerBox units themselves (i.e., not the PowerBus hubs) also have this isolation capability...but not 100% certain, as communications on the PB forum were less than perfectly clear (language/translation barrier.) My new ASW-17 uses the Competition unit without PowerBus hubs, and I'm wiring it with just the two flight packs.

[BryanB]

That would be great if the PowerBox unit itself has the cut out. I'm still not sure if I need to use the PowerBus feature just yet. But if it offers circuit isolation due to current overload then it would be worth it just to put the gear on at least.

[BryanB]

Did some browsing on the PowerBox forum, phew not easy, but anyway I saw your post and another similar and it sounds like no circuit isolation for the PowerBox unit itself. The PowerBus units have auto-reset fuses that activate at around 7amps. At least that's what I understand from what Richard German had to say.

[DanR]

I'm finally getting around to installing and programming the Hacker DPSI OCP on the retractable landing gear on the ASW-20.

Len, do you set it up to turn off the servo if an over current situation happens or do you have it retry every 5 seconds?

Also the programming instructions call for doing a flight with the module in programming mode so it can determine the normal current needs of the servo. Since this is for the retract, do you just operate the retract a few times on the ground then stop programming mode?

Thanks,
Dan