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HomeAircraftHelicopterRadio - Futaba FASST › Futaba BLS451 & BLS252 on 2S LiPo no Voltage Regulator
04-01-2018 08:24 PM  77 days agoPost 1
JLF92677

rrApprentice

Southern California

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Can anyone comment using 2S LiPo straight (no voltage regulator) with Futaba BLS451 & BLS252 servos?

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04-01-2018 10:15 PM  77 days agoPost 2
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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/
/

Well, both servos are Not high voltage application, so don't do it.

6 volts are max nominal voltage.

/

Saludos cordiales,

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04-01-2018 10:47 PM  77 days agoPost 3
Dr.Ben

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Richmond, VA, USA

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Life voltage is fine. LiPo - some do it safely but you are off the reservation from recommended specs for the servos, so you proceed at your own risk.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

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04-02-2018 04:37 AM  77 days agoPost 4
JLF92677

rrApprentice

Southern California

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Dr. Ben, yes I understand that subject servo spec. is 6V and anything above it is off “the reservation” as you put it. On the other hand, I have read reports that some pilots as Bobby Watts have applied direct 2S LiPo voltage to same, so my real question is what is the experience of others that have tried it or tested this type of setup? ie: JR 8717 servo (not 8717HV) is not a HV 2S LiPo servo, but many pilots use the 8717 servo with 2S LiPo setup with no issues; hence is this a real hardware limitation or just a published spec limitation of its time with enough design margin for HV application? Not asking for Futaba’s endorsement, just for the RC pilot community experience.

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04-02-2018 06:31 AM  76 days agoPost 5
Santiago P

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South West, Ohio

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I have been using a set of BLS451 on 8V regulated for about 40 3min flights without and issue so far. This machine only flies 12 times per year; we figure the servos will live long at this pace.
As reference, several counterparts in Europe also used the servos on nominal 2S voltage without problem, do not know how long. But never did heard a problem from them either.
On the other hand I would be scared to use a BLS252 with higher than what Dr Ben recommended.

Santiago

Team Minicopter - PeakAircraft.com
bavarianDEMON- Team Kontronik - Scorpion Motors-

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04-02-2018 09:04 PM  76 days agoPost 6
JLF92677

rrApprentice

Southern California

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Hello Santiago,

Thank you for your reply and feedback. With regard to your concern comment on the BLS252, are you referring to the BLS252 or perhaps BLS251 rudder servo which is rated for 4.8V only? Reason why I am asking, is because both BLS451 and BLS252 are from the same Futaba design time period and both are rated for 6.0V unlike BLS251. I am not questioning your advice, I just want to make sure I am on the same page.

Futaba BLS252 - Brushless Helicopter Servo Specifications
Modulation: Digital
Torque: 4.8V: 139.00 oz-in (10.01 kg-cm)
6.0V: 175.00 oz-in (12.60 kg-cm)
Speed: 4.8V: 0.16 sec/60°
6.0V: 0.13 sec/60°

Futaba BLS451 - Brushless High-Torque/Speed Servo Specifications
Modulation: Digital
Torque: 4.8V: 118.00 oz-in (8.50 kg-cm)
6.0V: 147.00 oz-in (10.59 kg-cm)
Speed: 4.8V: 0.13 sec/60°
6.0V: 0.10 sec/60°

Futaba BLS251 - Brushless Heli Rudder Servo Specifications
Modulation: Digital
Torque: 4.8V: 53.00 oz-in (3.82 kg-cm)
Speed: 4.8V: 0.06 sec/60°

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04-04-2018 12:49 AM  75 days agoPost 7
Rojoalfa

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Punta de Mata, Monagas-Venezuela

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/
/

Tweaking voltage on servos...
Very bad idea...

Servo fail in flight... catastrofic...

Having a good regulator is better than having a expensive crash...

/

Saludos cordiales,

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