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Old 12-22-2009, 03:51 PM   #1
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Default Unregulated LiPo

hello,

I have KO PROPO 2.4GHZ and Sanwa servos. The KR-408S reciever can apparently handle 7.4v no problems. My worry is can the Sanwa digital servos handle it?

Can I run 7.4v LiPo reciever pack directly into reciever, with no damage to both receiver or servos?

Running a regulator takes up too much room and weight, and the costs are stupid (~$30)

Would like to hear from others running the same/similar setup with no problems???
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Old 12-22-2009, 10:53 PM   #2
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Don't try it. I had burned a Sanwa servo before. I use spektrum receiver and it support 2S lipo. But the Sanwa sure don't...... Sorry can't remember what model it is I think it is a vz.

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Originally Posted by implusepro View Post
hello,

I have KO PROPO 2.4GHZ and Sanwa servos. The KR-408S reciever can apparently handle 7.4v no problems. My worry is can the Sanwa digital servos handle it?

Can I run 7.4v LiPo reciever pack directly into reciever, with no damage to both receiver or servos?

Running a regulator takes up too much room and weight, and the costs are stupid (~$30)

Would like to hear from others running the same/similar setup with no problems???
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Old 12-23-2009, 10:07 AM   #3
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Originally Posted by gpm-parts.com View Post
Don't try it. I had burned a Sanwa servo before. I use spektrum receiver and it support 2S lipo. But the Sanwa sure don't...... Sorry can't remember what model it is I think it is a vz.
Sorry.... maybe your sanwa got burned because sanwa erg-vz is analog servo. When you connect analog servo to spektrum receiver, analog servo's FET will get hot..... so hot until it burned itself. Please check your spektrum receiver manual regarding using analog servos.

Futaba HRS receivers also don't work with analog servos.
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Old 12-23-2009, 11:21 AM   #4
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Originally Posted by asw7576 View Post
Sorry.... maybe your sanwa got burned because sanwa erg-vz is analog servo. When you connect analog servo to spektrum receiver, analog servo's FET will get hot..... so hot until it burned itself. Please check your spektrum receiver manual regarding using analog servos.

Futaba HRS receivers also don't work with analog servos.


Mhhhh are you sure ?, lol !!!

I used 2 x 985mg's from Hitec (analog servos) for almost a full year on unregulated lipos and spektrum no problems at all in 1/8th offroad buggy.

cya
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Old 12-23-2009, 11:51 AM   #5
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I have used unregulated Lipo for a long time with Spektrum brand receivers. I have used this setup with digital and analog servos without any problems. The Futaba HRS can be used with analog servos but you have to regulate it so that the trasfer rate wont affect the servo.
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Old 12-23-2009, 03:01 PM   #6
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Originally Posted by jneg View Post
I have used unregulated Lipo for a long time with Spektrum brand receivers. I have used this setup with digital and analog servos without any problems. The Futaba HRS can be used with analog servos but you have to regulate it so that the trasfer rate wont affect the servo.
I'm pretty sure that input voltage have nothing to do with transfer rate. But I know that the Futaba HRS receiver can be used with analog servos if and only if it is in PPM mode. I've used unregulated lipos for spektrum receivers but not with the Futabas.
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Old 12-23-2009, 04:22 PM   #7
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Originally Posted by implusepro View Post
hello,

I have KO PROPO 2.4GHZ and Sanwa servos. The KR-408S reciever can apparently handle 7.4v no problems. My worry is can the Sanwa digital servos handle it?

Can I run 7.4v LiPo reciever pack directly into reciever, with no damage to both receiver or servos?

Running a regulator takes up too much room and weight, and the costs are stupid (~$30)

Would like to hear from others running the same/similar setup with no problems???
Run Life battery. It is only 6.6v. It won't fry your receiver.

http://www.rc-toro.com/product_info....oducts_id/1666
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Old 12-23-2009, 05:17 PM   #8
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Anyone running the Airtronics 2.4ghz system without a regulator? I thinking of trying it but not sure.
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Old 12-23-2009, 11:45 PM   #9
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Originally Posted by Tabushi View Post
Mhhhh are you sure ?, lol !!!

I used 2 x 985mg's from Hitec (analog servos) for almost a full year on unregulated lipos and spektrum no problems at all in 1/8th offroad buggy.

cya
HS985MG is entry level high torque servo, ie. no build in FET amplifier & no heatsink around the casing. HS985MG have simpler electronic component and design when it is compare to ERG-VZ. That's why you got no problem of overheating because 985MG don't have FET amplifier inside.

I have ERG-VZ, ..... once I connected it to Futaba HRS receiver, and the servo's heatsink become overheating in just 3 minutes ..... I notice something wrong in there but I don't know what. I keep doing it for another 5 minutes more.... luckily I decided not to gamble with it. I plug out the battery and change the receiver back to Futaba PCM 1024 R113ip. I right away notice the servo is not hot at all ( not even warm ) after changing receiver.

[ at that time, I though ERG-VZ is digital servo ].

In my buggy, once I try unregulated lipo 7.4V for simplicity reason. The receiver is Futaba R113ip 1024 PCM, and the servos are Hitec 5995TG. It's working, the servo turn the wheels very quick. I said to my self.... amazing ! I keep playing with it for another 5 minutes more to see if the heatsink become hot or too hot. Amazingly, it just normal warm, no overheating. ...... At the end of testing, after careful considerations, I decided not to use it like that .... I think it is stupid idea because the servo is already cost me $200, and I could buy LiFe battery for $40. You got what I mean, right
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Old 12-24-2009, 09:35 AM   #10
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Originally Posted by quietstorm76 View Post
Anyone running the Airtronics 2.4ghz system without a regulator? I thinking of trying it but not sure.
I e-mailed Airtronics and they told me the system wouldn't handle 7.4V. I would spend the $30 on a voltage regulator and be done with it.
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Old 12-25-2009, 08:37 PM   #11
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I e-mailed Airtronics and they told me the system wouldn't handle 7.4V. I would spend the $30 on a voltage regulator and be done with it.
The Rx cannot handle 7.4V. Hence you need a regulator for this. If you can try to replace with LiFe running on 6V. This might solve your prob without attaching more electronics on your car.
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Old 12-26-2009, 03:56 AM   #12
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1. Spektrum rx will handle input coltage up to 9.6v no problem. (The KO up to 7.4v)
2. Spektrum rx will handle both digital and analogue servos no problem.
3. You can run the servos unregulated and they will work fine (maybe even slighty quicker) but you run the risk of damaging them as they are not designed to be run at these higher voltages.
4. LiFe is a good solution that is becoming more widely available. A 2 cell pack is perfect at 6.6v if you can find the right size.
5. Companies (JR, Hitec) are starting to release HV (high voltage) servos for this application if you are buying new servos look out for them.
6. The simple answer if you are intent on using LiPo is use a regulator. They are very cheap and very light and you will maximise your servo life.
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Old 12-26-2009, 04:32 AM   #13
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I am using Spekrum SR3500 previously. Although the supported voltage is 3.2 - 9V. I still stick to NiMH at 6V. Reason is when u input 6V to the RX. The output is the same as input. Higher volts will kill the servos. Else you may consider a regular to be safe.. But I seen ppl got both servo's toasted when their regulator mulfunctions..

To date no servo manufacturer produces servo to operate at 7.4V for this case.
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Old 12-26-2009, 07:50 AM   #14
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Wrong!

Here is just one example...

http://www.hitecrcd.com/servos/show?name=HS-7940TH

or here is a cheap regulator that I have used that works well...

http://www.rcmart.com/catalog/rc-vol...3-p-28209.html


Do your research and be careful who you listen to!
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Last edited by getpip; 12-26-2009 at 08:08 AM.
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Old 12-26-2009, 09:29 AM   #15
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This year I have been running LiPo in my car combined with a Xceed regulator.
Didn't had any electronic problems whatsoever, actually this has been the first year that all of the electronics have been working flawlessly.
The Xceed regulator is extremely small and lightweight, I taped mine to the side of the receiver.
Used a 700Mah Lipo, which is just enough for 40 minutes of driving.
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