BEC Causing Servo/ESC Issues?

[JustAnOutcast]

I started down this path (rabbit trail?) when my new Outcast 6s EXB servo (S652) went bad after only a few runs…

The initial thoughts after consulting the good folks here was that the S652 is junk and a better servo is needed. I finally opted to stay with the stock parts while under warranty…

Anyway, to rewind the story, after a bit of servo research, looking for a good replacement, I started to be attracted to the top-of-the-line ProModeler servos. But after reading many blog posts there, and emailing the owner, John, it became clear that the voltages/current coming from the BEC can be erratic, spike under load from throttle demands, and generally an unclean source of power. So much so, ProModeler is adamant about using a separate power source (2s battery), for powering their servos. In fact, after some digging through the blogs, they don’t warrant their servos if not powered by a separate analog source (aka 2s LiPo).

Here’s the ProModeler blog post on synthetic voltages (from BEC) vs pure analog from separate battery source.

https://www.promodeler.com/askJohn/The-case-against-synthetic-voltage

So (I told you this was a rabbit trail), my question now is, in light of this information from ProModeler, could some of the S652 issues be coming from the BEC circuitry and not necessarily a total junk servo?

 

[#ARRMArcfanboy4life]

The BEC might affect the servo, but it is still junk. Most servos run well without the separate battery. They will likely run better on a separate battery (if designed for that voltage), but the stock servo (and other electronics are designed poorly).

 

[Moirae]

Get a hobby star servo from rc juice for 60$ or 40$ on sale and be amazed at the improvements over stock and the savings to your wallet.

 

[JustAnOutcast]

Get a hobby star servo from rc juice for 60$ or 40$ on sale and be amazed at the improvements over stock and the savings to your wallet.

Thanks. Is this a drop in replacement for the S652? No other mods?

The BEC might affect the servo, but it is still junk. Most servos run well without the separate battery. They will likely run better on a separate battery (if designed for that voltage), but the stock servo (and other electronics are designed poorly).

That seems to be the overwhelming consensus here, with few reporting acceptable performance.
I guess since there are many drop in replacements that work and don’t cause issues (like you said), that tells the tale of a junk servo. Would be interesting to know how many S652 would function normally with dedicated battery.

 

[Moirae]

Thanks. Is this a drop in replacement for the S652? No other mods?

That seems to be the overwhelming consensus here, with few reporting acceptable performance.
I guess since there are many drop in replacements that work and don’t cause issues (like you said), that tells the tale of a junk servo. Would be interesting to know how many S652 would function normally with dedicated battery.

https://www.rcjuice.com/servos/serv...speed-digital-brushless-waterproof-servo.html

drop right in. night and day difference from stock or the cheapo amazon one and you can plug it right into the rx. Will work even better whenever you ditch stock esc. Promodeler is definitely "better" but tbh I can't see why anyone would need more than that hobbystar servo on a 1/8th scale truck. I went from using the 32$ amazon cheapo that most people suggest after the stock one dies to the hobbystar one and if you told me that hobbystar servo was 100$ I would have believed it because it's amazing and cheap.

 

[JustAnOutcast]

https://www.rcjuice.com/servos/serv...speed-digital-brushless-waterproof-servo.html

drop right in. night and day difference from stock or the cheapo amazon one and you can plug it right into the rx. Will work even better whenever you ditch stock esc. Promodeler is definitely "better" but tbh I can't see why anyone would need more than that hobbystar servo on a 1/8th scale truck. I went from using the 32$ amazon cheapo that most people suggest after the stock one dies to the hobbystar one and if you told me that hobbystar servo was 100$ I would have believed it because it's amazing and cheap.

Seems you dropped this link in another one of my posts?
Anyway, got it, thanks! I’ll add it to my list of things to replace when warranty runs out.

 

[SrC]

So (I told you this was a rabbit trail), my question now is, in light of this information from ProModeler, could some of the S652 issues be coming from the BEC circuitry and not necessarily a total junk servo?

If you think about it, that Spektrum ESC BEC circuit is to blame per you interpretation. BUT, why are the S652's shorting out the ESC BEC's in many cases . It's only these Spektrum servos doing this. I say All Spektrum gear is subpar in general.

And getting back to PM servos. I stated elswhere that PM is an AIR RC brand. Always has been. And Air RC's don't have a BEC. The aux surface control servos are always separately powered with a battery. Mostly for Failsafe reasons mid flight. If the ESC's... Mains power Fails and you lose propulsion, you can glide back safely with separately powered servos. PM aligns themselves with this concept. Their Servos are designed and tested with a clean Non BEC power source. Not tested wth the many Surface ESC's out there. They are not technically a Surface RC company brand and Never were. . If Their servos absolutley require a Battery, then they are not suited for Surface use at all IMHO. Yet many use them with a BEC successfully. Their disclaimer just is what it is. And their servos are well known to be high quality using Japanese Motors and potentiometers. You pay for this precision. PM has huge Gov't contracts for Mil-spec Drones. Maybe PM is overkill for simple bashing, It's your wallet.
I stay with the Cheap DS3235's. I'm good.
I can't justify any Modern RC basher rig using a dedicated battery just for steering. Maybe for Nitro rigs, the norm.

 

[JustAnOutcast]

If Their servos absolutley require a Battery, then they are not suited for Surface use at all IMHO.

I can't justify any Modern RC basher rig using a dedicated battery just for steering.

Agreed. And after a fair amount of research and the owner’s insistence on a separate battery, I’m convinced the ultra precision of a PM servo is only possible with a dedicated battery source.

 

[#ARRMArcfanboy4life]

Agreed. And after a fair amount of research and the owner’s insistence on a separate battery, I’m convinced the ultra precision of a PM servo is only possible with a dedicated battery source.

By the way, Reefs rc has some servos that use a separate battery.

 

[JustAnOutcast]

By the way, Reefs rc has some servos that use a separate battery.

Yes, thanks. I looked at those and the others you suggested and got the feeling of being overwhelmed, over my head, much like with ProModeler.