cplus

iTrader: (11)

There seems to be a plethora of HV servos coming onto the market, with most of the major brands - and even the smaller specialised ones - coming on board with a low profile offering with typical TC specs;



Standard footprint
25mm ish height
<0.10 60 deg (most well under when on 7.4v)
>7kg torque (most well over when on 7.4v!)

But how are they being powered?

I'm not aware of any top end ESCs with more than a 6V BEC, so to take advantage of the HV specs, would need either direct wiring to lipo, a dedicated RX battery (and a receiver that can handle HV) or a 7.4v external BEC

The former leaves you open to a servo that changes pace as the race goes on and voltage drops from full charge 8.4V to ~7.6V (or what ever you see after your runs) and latter two mean added weight & complexity, plus the possibility of the BEC wiggling out under acceleration and high motor current draw when voltage can drop sharply.

I use HV servos in my 5th scale with a dedicated receiver pack wired direct to them and it works really well - I barely seen 0.1-0.2V drop over a 20min run, so no performance drop off noticed.

Surely someone is using one?

Skiddins

Those specs aren't that impressive, even for 6V

I think most high voltage servo's are designed to be used in nitro vehicles where a lipo receiver pack etc is used.

Skiddins

Ho1aw

I use a new brand.
Power star PM-1610. Brushless, full metal case.

R3VoLuTiOn

iTrader: (29)

I have that actual Futaba servo in my electric tc.

Its great, quite similar to a 551, and come nitro season, I can run lipo rx packs on them.

rhodopsine

Tekin RSX ESC have adjustable BEC voltage to 7.4V

Martin Paradis

Roelof

Most of the time the + wire of the servo can be re-routed directly to the battery.

But fast 6v servo's can be found with fast speeds up to 0.05sec so there is no need for a HV servo.

bertrandsv87

iTrader: (2)

The only logic behind a HV low profile servo in a tc, is that you will not have to buy another servo if you decide to put it in a nitro car that runs on a 7.4volt lipo... The protek 160SS is the best out there for the price....lol....

cplus

iTrader: (11)

Sorry, misleading, I was merely quoting "typical" minimum TC specs, not the specs of that servo in particular!

I think you are right for the moment. Means they can be used for either. But if you have one and get get more performance at higher voltage, surely would look to take advantage at some stage?

And how have you wired it?

Yep, seems very similar specs to (my) 551, just more torque if you run it at HV

Ah, there we go, they are coming. I think this will start to be more common....

Yep, you can do that, but servo performance - and likely your driving lines - will change dramatically from start to end of the run as the voltage of your main pack drops. That would be crap.

If a servo can make the same speed, have more torque, but be more reliable, fit in a smaller, lighter case and use less power - would you consider it?

Oh, but it has to run at 7.4V......

"Only" logic to you maybe.

Get used to all the big brands only having HV options at the top end of their ranges.

"Best" is also very subjective. On paper is one thing. Real world is often another.

Roelof

Todays needed torque is highly overrated (in every class). I do run a stock S3001 on my touring. OK, it can be faster but it is not needed on outdoor tracks. The 3kg torque is enough. The 6v/0.05sec spec servo's do have 4 or 5kg torque, that is more than enough.