Servo operating voltage & battery voltage question

[Jake Ellwood]

Hi all,

Currently in the process of replacing some batteries in my boats from standard packs to Life.

Some of my servos are Hitec HS-5086WP which the manufacturers site states:
-----
Operating Voltage Range (Volts DC) 4.8V ~ 6.0V

Now the battery in question:
-----
Capacity: 2100mAh
Voltage: 2S1P / 2 Cell / 6.6V
Discharge: 20C Constant / 40C Burst

Apologies in advance if this is seen as a stupid question. But am I likely to run into problems running these servos from this battery? I guess my concern is the voltage max on the servo is 6.0V and the battery runs up to 6.6V

Thank you in advance for any help

 

[john v]

talk to steve at offshore electrics , he will know

 

[Jake Ellwood]

talk to steve at offshore electrics , he will know

Thank you

Is he on this forum?

 

[Grimracer]

Jake

I really like LiFe packs.. BUT.. if you do not have high voltage servos IT IS BEST to use a voltage regulator. The Castle unit is 20 or so dollars and solves the issue.

The packs you have listed will be fine..

This is the regulator I use.

https://futabausa.com/product/ps-10br/

Yes. the servo WILL operate without the regulator BUT.. you will be spinning the chamber as to how long they will last.

Grimracer

 

[Jake Ellwood]

Gotcha, thanks Grimracer. Never knew these existed.

Does such a thing exist to regulate voltage on a per servo basis?

For example, in my big cat I've got a D956WP which has the following specs

Performance Specifications
Operating Voltage Range (Volts DC) 4.8V ~ 7.4V
Speed (Second @ 60°) 0.19 ~ 0.12
Maximum Torque Range oz. / in. 251 ~ 405
Maximum Torque Range kg. / cm. 18.0 ~ 29.0

This is on the rudder. Then I have 2 of the aforementioned smaller servos for the carb and mixture valve. My thinking is a voltage regulator would stop the 2 smaller ones from burning out but would limit the performance of the rudder servo? (no idea how much half a volt would affect it)

EDIT: Just found this https://futabausa.com/product/ps-01rs/

That seems perfect

 

[Grimracer]

yes.. BUT.. they are made for tail rotor servos on helicopters. The current requirements of a boat servo would be too much for those regs..

Its not the .5V.. its the peak voltage and average higher voltage. Its higher then .. it can be 7V or more.

Also remember.. the 6V they call out is the MAX input voltage.. above the normal voltage range.

IF cost is an issue.. the Castle unit is not much money.. about 20 bucks. they do work well. I know quite a few guys using them and I have used them too...

Grim

 

[Mikemalloy]

Jake, I’ve been running all Savox HV servos w/ 2s Lipo in all my boat setups (rudder,throttle). With no issues. Before HV servos were available years back I used 6.6v live without any voltage regulator, in my FE,Nitro and gas boats no issues. A fully charged.6.6v life will not harm a servo that says it’s Rated @ 6.0v. When the battery is turned on yes it gives a 6.5v, 6.4v reading but you are also powering up a receiver 1,2 or 3 servos depending on set up when the servos are actuating I believe there is a voltage drop (minimal) at servo(s) around the 6.0v+—. I hope I didn’t confuse you, it was the easiest way I could explain it.
Also as far as Brands of servos I’ve used them all over the years Futaba, Savox Hitec, Protek ect...they all work, it comes down to preference and color of the cases. Lol.

 

[timothy johnson]

I called Hitec about your question about 6 volt vs 6.6 LIFE, a number of years ago. I was told it was a non issue, no problem.

 

[Jake Ellwood]

Thank you all for your replies - very helpful, insightful and educational. However if Hitec themselves are saying its fine with a thumbs up, thats good enough for me.

Also @Mikemalloy - funny you mention about case colour. I do like the Hitec blue - but use them primarily due to them being IP67 rated. I find it amazing Futaba does not supply such a servo, if they did I'd go all in with them as for donkeys I have always used Futaba equipment. The Futaba servos in my Aeromarine Predator are 20 years old at this stage now and still functioning perfectly. Also not to mention years ago (in the UK at least) Hitec had the nickname of "lowtec" due to regular failures and problems experienced.

Like most companies these days though, they must have upped their game to stay in the game and now the quality of their products is really high in my opinion.

 

[Daniel's Racing]

It is a non issue. A fully charge 5 cell NiMh is same as 2 cell Life. Never a issue with 6 volt servo's.

I have sold many thousands of LiFe packs and never heard of a single person using a regulator or burning a servo.

 

[Grimracer]

Daniel, Count me in as one.. LOL.. man that one sucked.. Only happen one time to me.. never ran servos out side there voltage spec again!..lol

and sure.. they blame the servo.. (hitec HS-80s or 225s how about the 645... do they come to mind?).. they do to me.. 6V on those old dogs (not even 6.6) and they just did not last.


Also Jake.. 20 year old servos LIKELY used on proper voltage.. did you not answer your own question?

"The Futaba servos in my Aeromarine Predator are 20 years old at this stage now and still functioning perfectly"

Just thinking.. not jumping on anybody..

Let her rip!... I support any and all decisions ya make on this.. I am just relaying.. its best.

Grim

 

[Danny King]

I can honestly say the only servo I have had a failure with on 6.6 is the hitec 225. They sure seem to not last as long. I run all hitec and it’s the only one. The solution is the digital version. I replace everything with digital now and the reliability and performance is far better.

 

[Kris Flynn]

For what it is worth, I have been using hitec NON HV servos (HS85 for example) and LIFE receiver packs for many years with no issues.

If it were my boats i would be using those servos straight from pack and no regulator, however i like the idea of the regulator supply a more constant voltage, but I have not seen a huge need for that myself.

 

[Daniel's Racing]

Daniel, Count me in as one.. LOL.. man that one sucked.. Only happen one time to me.. never ran servos out side there voltage spec again!..lol

and sure.. they blame the servo.. (hitec HS-80s or 225s how about the 645... do they come to mind?).. they do to me.. 6V on those old dogs (not even 6.6) and they just did not last.


Also Jake.. 20 year old servos LIKELY used on proper voltage.. did you not answer your own question?

"The Futaba servos in my Aeromarine Predator are 20 years old at this stage now and still functioning perfectly"

Just thinking.. not jumping on anybody..

Let her rip!... I support any and all decisions ya make on this.. I am just relaying.. its best.

Grim

My point here is any servo that is good on 5 cell NiMh is also going to be fine on 2S LiFe because
LiFe is not anymore voltage. A LiFe settles down off the charger to 6.6 to 6.8 volts and a fully charge 5 cell NiMh is exactly the same or maybe even the NiMh a bit higher. ​

Those are actually 4.8 volt rated servo's or 4.8 to 6 volt maybe but yes I guess if you are still trying to run those old junk servo's maybe there are some but it is usually servo's that have been around forever and are actually designed as 4.8 volt.
Those it will damage but if they were fine on 5 cell NiMh then 99.9% of the time they are ok on Life.

Every servo you mention that it had a problem with are problem servos to begin with. The 645 was good at one time but the later versions were total junk as they have been ever since. I think you are just burning up the servo period and it still would have occurred with NiMh and the reason I say that is every one of those numbers as I remember were subject to failure on 6 volt Nicd or NiMh just the same.
Because it burnt up and you were using a LiFe pack doesn't positively mean it was the LiFe packs voltage that did it.
If your still running boats with numbers like those you should stick with NiMh or maybe just solder some dry cells together. Lol.
In any case if you have ones that are 4.8 volt compatible common sense would tell you even 6 volt is over driving the crapola out of it already. Those were never 6 volt servo's when 6 volt came along they just changed specs to include 6 volt but it was still a 4.8 volt servo. Old timer servos they upgraded the specs on without changing anything like you said burn out with 6 volt so sure then again common sense would tell you 6.6 won't make it better or any different maybe because like I said it is the servo burning up the same on LiFe as it does on 6 volt also so not really the extra voltage of LiFe just that it isn't good for 6.6 volt as fully charged a NiMh is nearly that anyhow. They were never REALLY 6 volt servos.


Get the good stuff. Digital baby.

 

[John Beardslee]

So Daniel, dry cells? Early in days of proportional radios & servos we used 4 dry cells in the receiver packs, that chemistry gives you 1.5 volts per cell, 4 cells gives 6 volts. The servos were built around that voltage. Many of our heli tail rotor servos were extremely voltage sensitive 4.8-5 volts max. When I made the switch to the new battery chemistry I ran a regulator for only the tail servo, all others ran with zero failures since, that was when lithium chemistry was in it’s infancy. I’ve used servos from all the major manufacturers with minimal issues. Giant scale airplanes, heli’s, foamies and boats. Once A123 LiFe cells came on the market I made a wholesale change to that recipe and have never looked back.
Thanks John

 

[Daniel's Racing]

So Daniel, dry cells? Early in days of proportional radios & servos we used 4 dry cells in the receiver packs, that chemistry gives you 1.5 volts per cell, 4 cells gives 6 volts. The servos were built around that voltage. Many of our heli tail rotor servos were extremely voltage sensitive 4.8-5 volts max. When I made the switch to the new battery chemistry I ran a regulator for only the tail servo, all others ran with zero failures since, that was when lithium chemistry was in it’s infancy. I’ve used servos from all the major manufacturers with minimal issues. Giant scale airplanes, heli’s, foamies and boats. Once A123 LiFe cells came on the market I made a wholesale change to that recipe and have never looked back.
Thanks John

I am going back to the same era 1970's up until the 6 volt jump to 5 cell occurred and even those were 5 cell NiMh when that change occurred but remember everything high end were powered 4 cell X 1.2 volt NiCd rechargeables packs that everyone used that gave that voltage so many servos were made for power at that low 4.8 volt voltage because it was what everyone was using.
Otherwise they would be too sluggish on the 4.8 volt NiCd packs. Remember the servos didn't have the torque of todays.

Still remember some of the old Futaba numbers like the S-7 and S-29 one was even waterproofed. The beige colored ones maybe it was the S-7 that was 45 years ago.

 

[Bill Gibson]

I am going back to the same era 1970's up until the 6 volt jump to 5 cell occurred and even those were 5 cell NiMh when that change occurred but remember everything high end were powered 4 cell X 1.2 volt NiCd rechargeables packs that everyone used that gave that voltage so many servos were made for power at that low 4.8 volt voltage because it was what everyone was using.
Otherwise they would be too sluggish on the 4.8 volt NiCd packs. Remember the servos didn't have the torque of todays.

Still remember some of the old Futaba numbers like the S-7 and S-29 one was even waterproofed. The beige colored ones maybe it was the S-7 that was 45 years ago.

Still have S-7s, S-28s, and S29s....they still work and i still use em in small, .19 powered airboats i play around with...even a tan receiver on 26.995!