Marcos_Nieto

Hi guys.............I´ve been in this hobby for a long time now, retired for a while and came back a couple of years ago. Since then a lot of things have changed, specially in radio-battery-servos field.
I´ve always used 4.8 volts Rx pack and want to know the advantages, if there is any, of using 6 volts pack.....According to the servos specs the torque and speed increases when you go from 4.8 to 6 volts pack (this seem to be a very good plus)......Having an extra 1.2 volts battery in the pack will give you about 25% more pack capacity(not flight time), this because the power consumption will go up as it is proportional to torque and speed (say volt-amp). Also the pack weights 25% more.

Are the servos gear set designed to work with this extra torque?? What are the pros and cons of using one or the other???
Thanks

Marcos

smokingcrater

sounds like you already got all the points! more torque, speed, less flight time/capacity. most rc stuff is fine on 6 volts, although it may twitch some on a fully charged pack. many gyros and digital servos are NOT ok on 6v though...

SwampFlier-RCU

Added bonus of 6.o v packs is that if one cell gets damaged you still ahve 4.8 volts to operate the radio.. just one mor advantage
i have changed most of my planes to 6.0 volts 1100 mAh Nicd's and no problems whatsoever
My best planes have a Reliaswitch form Fromeco
www. rcshowcase.com or www.fromeco.org
Add :"The Regulated Reliaswitch will regulate to an output voltage of 5.2VDC for 5 cell NiCad or Duralite battery packs. The maximum output current is 3 Amps. More than enough for most model aviation use. "

hilleyja

My Feedback: (3)

This is not the case with Hitec digital servos. They are all compatible with 6volts.

hilleyja

My Feedback: (3)

I certainly wouldn't consider this an advantage. The damage may be a short which potentially would then cause the other cells to fail. Also, (Red correct me if I be wrong) a 6 volt pack will discharge below its working voltage faster than a 4.8 volt pack. Don't treat a 6volt pack like a surpercharged 4.8 pack. When the voltage gets close to 6.0 volts then DO NOT FLY WITH IT. If you have a cell go bad in any battery pack -- DUMP the entire pack, its not worth losing your airplane over the cost of a battery pack.

RJConnet

"When the voltage gets close to 6.0 volts then DO NOT FLY WITH IT."

Boy do I hate to see flat statements like this with no qualifiers, a 5-cell pack that measures 6 volts may very well be fully discharged. The same pack fully charged may measure 6 volts with some load. Also, I'd like to know how an internally shorted cell could damage other cells in the same pack.............. RJ

XJet

Are you aware that the *nominal* voltage of NiCad and NiMH cells is 1.2 volts per cell?

That means a 4-cell pack showing 4.8V and a 5-cell pack showing 6V under load probably has at least half its charge remaining!

NiCad and NiMH cells are considered to be discharged once they reach 1.1V per cell -- which is 4.4V for a 4-cell pack and 5.5V for a 5-cell pack.

I would be happy to fly down to 4.6V and 5.75V on 4 and 5 cell packs respectively.

hilleyja

My Feedback: (3)

If you want to submit your $1000.00+ airplane to the battery pack's projected low ends its your decision.

My decision (whether it be scientifically right on or wrong) is the 4.8volt packs get peaked when they discharge below 5.0 volts and the 6.0 volt packs get peaked when then discharge below 6.0 volts. NICADS get cycled on a periodic basis and NIMHs get cycle at least once per season.

Yes, I understand that a cell is considered to be at full discharge when it reaches 1.1volts. This means a 4.8 volt pack SHOULD be good down to 4.4+ volts and a 6.0+ pack SHOULD be good down to 5.5volts. I opt to be extremely cautious because, correct me if I'm wrong, a bad pack near its discharge point is more apt to go totally bad real quick.

Why do I need to qualify a conservative RECOMMENDATION. Am I recommending something that may be detrimental to someone's airplane? Actually, you enhance my point when you said Especially NIMHs which discharge much faster the closer they get to their low points.

I guess your right here. A cell that fails not shorted would fail the whole pack. A cell that shorts would only knock the voltage down be one cell -- lets hope I never have a 4.8volt pack develop a cell short.

SwampFlier-RCU

Jim I think you misunderstood my post what I was saying is that if you're flyin (i.e., in the air) at the time of a 6 V battery failure (internal short) you still would have 4.8 volts available to the system so you may be ale to bring your whatever $$ plane youhave bak to earth and then TOSS the pack... I never said you should continue using a damaged pack.

hilleyja

My Feedback: (3)

SwampFlier-RCU,

Actually, I didn't missunderstand your post at all. My responses were directed towards RJConnet hollier-than-thou statement "Boy do I hate to see flat statements like this with no qualifiers" Rather than take a poster's input and provide some helpfull clarification and/or correction he feels he must deride the poster.

Hope I don't generate his or your ire when I say, any cell failure, whether it be a 6volt pack or a 4.8volt pack can be detrimental to the inflight airplane. I don't think its a good idea to run 6volt packs just because you think it protects you from a cell failure. Run the 6volt pack because it provides you enhanced torque and speed for your flight controls.

As a minimum, you should check your flight pack battery before flying for the day. If it is at its peak then you are probably good for several flights. If it is at its lower range then my standard is no more than one flight before charging. I base my decision on the flight pack. 5.5volts does not give me a warm fuzzy when the pack is a 6.0volt pack, it could be down to effective zero is a very short time -- I would never fly with it. I operate on even a more conservative standard -- I wouldn't fly if it is less then 6.0 volts. Likewise, I would not fly a 4.8volt flight pack if it is less than 4.8volts and usually will peak charge if it is less then 5.0volts. All of this conservatism is based on the knowledge that a battery pack discharges to unuseablity much faster when it is near its low point than when it is peaked.

I've had switch problems in the past but have never had a battery pack failure. As a matter of fact, I have only retired 2 battery packs in the last 5 years. BTW, my source of batteries is wide open. I get packs from name-brand sources and packs from fly-by-night sources. I initially check them all and routinely check them on a regular basis.

BTW, I believe all of my past switch problems were actually not switch problems but switch-mounting problems. When you mount a small switch you need to make sure you carve the square hole big enough for the slide to completely move left and right. I have solved my switch problems by standardizing with DSC and MPI switches. These switches are heavy-duty double-pole switch/charge recepticals. The entire switch box is mounted within the hole on the fuselage, instead of just the slide.

TLH101

My Feedback: (90)

Check this thread, lots of good dicussion including some important points about "cut-off" voltage:
http://www.rcuniverse.com/forum/m_18...tm.htm#1916264

lex2bits

My Feedback: (12)

Nieto,

Go here for authoritative info:

http://www.rcbatteryclinic.com/

Lex [8D]