Conference vmszoo::rc

    
    Disclaimer: I am not an electronics expert ( to say the least! :), so
                I don;t know if there are any bad long term effects to
                using a 6.0 pack. 
    
        I recently bought a 6.0v 250mah pack at RC Buyers to give it a try.
    I originally went in to purchase a 4.8v pack, but Bob mentioned he had
    5 cell packs that several people had been running with good success. I
    was concerned about the reciever being able to handle the high voltage,
    but he said several people had been using them successfully with
    several different brands of radios. I decided to give it a try, and am
    using it with an RCD reciever.
    
        Supposidly, the advantage is greater servo speed. I have flown
    once with it installed, and to be frank, didn't notice any difference
    in a fun fly type airplane. Maybe the difference will become more
    apparent in future flights, we'll see.
        
    
                                                             Dan

    I called Futaba in Irvine, California today to discuss narrowband
    conversion prices and options on one of my radios.  I asked the Futaba
    rep (who was a tech) if I could use 6.0V batterys with a Futaba
    reveiver.  He said there would be no problem that the receivers were
    designed to handle up to 6.0V.  Now I'm wondering if I should install a
    resister or somthing on the wire between a 6.0V battery and the Rx to
    kill any early over 6.0V current that initially comes from the battery.
    I understand that when you take a good nicad battery off of a charger it
    initially puts out slightly over its rated voltage for a short period. 
    I understand that a 4.8V battery can put out 5.3V for a short period of
    time. I want to make sure that early voltage won't fry my new receiver
    or cause any long term cumulative damage that eventually kills my Rx. 
    Im going to call the folks at SR and see what they think, I will post
    their answer here
    
    Will 

    Most RX systems will run with a 6V pack but I wouldn't recommend it. 
    Your receiver has a voltage regulator that will run hot and your servo
    amplifiers may run hotter and be more prone to failure.  The main
    advantage is faster servo transit times and higher servo torque. 
    Another slight advantage is that you can have a cell short and still
    have four good ones.  By the way, you will NOT get longer flying time
    with a 6V pack vs a 5.2V one.  You might even have shorter safe
    duration because the current draw could be slightly higher depending on
    how the servos and receiver behave with higher supply voltage.  If you
    want to carry the extra weight, I'd recommend using four cells of
    the next size up in capacity.  
    
    Charlie
    

    What makes you think that you would notice greater servo speed. ;-)
    
    Full-up is Pull-up right?.  :-(
    
    
    The answer to the 5-cell pack question is that certain brands need five
    cells to perform up to spec.
    
    The pattern guys started using five cells to get consistant responses
    from their "high-speed" servos. Unless you are having problems I would
    not go to five cells. Due to the complications that they pose to regular
    cyclers and chargers.
    
    Some pattern guys go so far as to charge up between every flight. They
    are so much in tune with their planes that the slightest servo
    performance deviation can throw them off their routine.
    
    Can't say it's affected me yet???.
    
    E.

    Will,
    	Do not put a resistor in series with the pack.  This can cause big
    voltage transients when the servos pull power from the pack.  Just
    curious, but why would you want to run 6V?  Your standard charger won't
    charge it properly and the system was designed to run on 5.2V.  I saw
    an article about 5 cell RX packs in one of the mags recently and only
    one manufacturer recommended against using 5 cells in their equipment.
    You can do it, but don't put in a resistor!
    
    Charlie
    

    Good or bad.. the big gliding boys and the F3F'ers in our area have been 
    doing it (5 cells @ 1.2v)for several years, after all the radios are 
    still specified to work on dry cells which are 1.5v each..
    
    Trev.

    The reason why I have been considering 6.0V packs is because I am
    building a quarter scale Citabria.  I thought there might be some
    benefit from the additional power to the large servos.
    
    On a secondary note I may have stumbled across somthing of interest.  I
    ran two futaba flat Rx packs in two different planes (same packs) over
    two consecutive years four years ago.  These were 4.8V 500MaH packs run
    on two separate on/off switches.  I have been going through all of my
    nicads with an ACE Digipace to determine their health.  These two flat
    packs were always run and charged identically.  They both tested right
    at 500 MaH this week!  I talked to a local RC fan who told me that if
    you don't heavily discharge nicads they will last a long time.  I am
    just amazed that at five years old these things have such excellent
    output remaining.  For what its worth they were never in a plane that
    crashed, they were always well foam padded and both planes had soft
    mounted engines.
    
    I like to think I err on the conservative side with my RC flying. 
    Given the potential for harming the Rx over time I may just stick with
    4.8V packs with a 1200MaH rating and run a pair of them for redundancy.
    
    I appreciate all the feedback!
    
    Will
    

    Will,
    	I think that's the right idea.  Go with 1200 packs with 4 cells. 
    Keep them charged when not in use and don't overcharge them and they'll
    last a long time.  You can run lots of servos on a 1200 pack.
    
    Charlie
    

    Will,Charlie,
    
    I think 1800's are also available in the same case size.
    
    Trev

Yeah, check around the battery manufacturers. At last year's WRAMS show
I got a couple of 1000maH packs thaty were slightly longer AA cell 
configurations. Since I generally end up using nose weight in my gliders,
these slipped into the same space (albiet a little longer) and the nose 
weight was useful. They had 1300maH in the same form factor.

    Be VERY careful with high capacity packs for RX.  They are supposedly
    much more sensitive to Vibration.  The cell construction is much weaker
    to make room for extra active material in the same cell size.  Some ads
    even say not recommended for airborne packs.  You can get 1400 cells
    that are pushed 1200's that should be good.  The 1700 and 1800's are
    the SCE type which I wouldn't use for RX.  The SCR type are very
    rugged.
    
    Charlie