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HomeAircraftHelicopterRadio - Futaba FASST › Futaba BLS451 & BLS252 on 2S LiPo no Voltage Regulator
04-01-2018 08:24 PM  3 months agoPost 1
JLF92677

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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  3 months 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  3 months 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  3 months agoPost 4
JLF92677

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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  3 months 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  3 months agoPost 6
JLF92677

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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  3 months 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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06-27-2018 03:44 AM  19 days agoPost 8
hyflyr

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Baton Rouge, LA

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Can't comment on the 252's but always ran 2s on BLS451's. Never had a failure. Hard 3d for years on multiple sets.

Scott

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06-27-2018 04:04 AM  19 days agoPost 9
JLF92677

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Southern California

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hyflyr, thanks for your reply and sharing your experience.

Just to confirmed, you used 2S LiPo, NO VOLTAGE REGULATOR with Futaba BLS451 servos, correct?

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06-27-2018 08:56 AM  19 days agoPost 10
Heli Fanatix

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Fountain Valley, CA

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Here is something to consider:

Do we really have to run these BLS 451’s @ a full 2S Lipo?
- LIFE will be more than sufficient
- convenient setup [no switch/regulated/straight to FBL]

I have been running all my set up @ 5.6V
- full hard 3D
- quick and did what I needed to do

I’ve seen folks run 8.4V just to add more expo and rate to offset the increase speed from running the high voltages.

It appears the OP is looking for validation to using 2S
- yes it will work no problem
- however if we value “PEACE of MIND” > just use a LIFE 2S, call it a day and go fly!

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06-28-2018 03:32 AM  18 days agoPost 11
JLF92677

rrApprentice

Southern California

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Heli Fanatix
Here is something to consider:

Do we really have to run these BLS 451’s @ a full 2S Lipo?
- LIFE will be more than sufficient
- convenient setup [no switch/regulated/straight to FBL]
Heli Fanatix, thank for your reply. I am fully aware of 2S LiFe technology, I actually have them and use them. This post as indicated on the title is with regard to the use of 2S LiPo with referenced servos and experience of other pilots that have employed same and NO VOLTAGE REGULATOR with BLS451 and or BLS252.
Heli Fanatix
It appears the OP is looking for validation to using 2S
- yes it will work no problem
As I understand your above response, you indicate that that you have used 2S LiPo with NO VOLTAGE REGULATOR with BLS451 and “yes it will work no problem“, correct?

Thanks again.

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06-28-2018 03:35 AM  18 days agoPost 12
hyflyr

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Baton Rouge, LA

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Yes 2s lipo no reg. Still running it.

Scott

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06-28-2018 03:40 AM  18 days agoPost 13
JLF92677

rrApprentice

Southern California

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hyflyr
Yes 2s lipo no reg. Still running it.
Thank YOU very much for your confirmation! Much appreciated!!!

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06-28-2018 04:53 AM  18 days agoPost 14
Heli Fanatix

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Fountain Valley, CA

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Here is the question:

Why do we need 7.2V vs 6.0V?

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06-28-2018 06:09 AM  18 days agoPost 15
JLF92677

rrApprentice

Southern California

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Heli Fanatix
Here is the question:

Why do we need 7.2V vs 6.0V?
That is not “the question” on this post. Not interested in debating that question. You are welcome to open a post with that question if you wish.

However, the question pursuant to your prior response is:
JLF92677
Heli Fanatix
It appears the OP is looking for validation to using 2S
- yes it will work no problem
As I understand your above response, you indicate that that you have used 2S LiPo with NO VOLTAGE REGULATOR with BLS451 and “yes it will work no problem“, correct?

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06-28-2018 07:08 AM  18 days agoPost 16
Heli Fanatix

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Fountain Valley, CA

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Of course .. typical attitude based on your many response and many request to “CONFIRM”

Wouldn’t need to post a thread on 7.2v vs 6.0v b/c the answer would most likely be:
“minimal gain vs potential risk especially for your 4.8v rated servo”

Servo is subjecting to 8.4V!!!

Example:
If our car has a Redline of 8,000 .. why not rev it pass that day in and day out, let’s see what happens!

If you are not open to a healthy debate, than it just “CONFIRMS” you don’t want to LEARN and only hear what you want to hear.

Give advice to a wise man, they will say “thank you” ...Give advice to a fool and they will trivilize what they don’t understand

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