Conference vmszoo::rc

RE: < Note 888.0 by TONTO::SCHRADER "Buddy can you Paradigm?" >

>    3V and 600mah per AA size cell! Yep, that's right, about double the
>    power density of Nicads. 

    This is double the power per unit volume, but I wonder about their
    weight (power density).  If each lithium AA cell weighs the same as
    a NiCad AA cell, then they will be double the power density.

>    If they will supply high enough currents then this will be an absolute
>    godsend to you electric motor folks, and I wouldn't mind dealing with
>    a battery 1/2 the size of what i've got now either. Bye for now...

    I'd like to be optimistic, but I'll bet they won't put out the 15 to
    30 amps we need.  However, they should work GREAT for receiver
    packs.  Just think, 600mAH with only 2 cells!

    I'll be waiting to hear some specs. on these batteries.

                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Caster Oil!! "    
                      |_____/

>     While leafing through my latest issue of Electronic Component News
>     last night, I ran across something that could have a really big
>     impact on our hobby. 


Nothing really "new"....  The standard Lithium Magnesium non-rechargable cells 
are used in memory back up, and those types of applications.  A standard
non rechargeable "c" cell is about $15 a whack.  I was able to pick up a few free 
samples last summer - nice, but EXPENSIVE.  I did quite a bit of digging for 
the *best* batteries/cyclers for the hobby a year or so ago.

The rechargeable lithium cells are going for about $25 per cell - or $100 for 
your receiver pack!  No thanks.  My grandfather just picked up a set for one 
of his ham sets, but the price will have to come WAY down before I'll 
fly that kind of battery investment around!  He bought them from the same 
out fit in Canada.  I got that poop sheet that your referencing also.

If you are interested other batteries, for the $$ the Zinc-air provides almost 
the same bang that the Lithiums provide for about half the price.  Duracell 
now manufactures both.  

I've concluded that at least for now, until the prices come down on the 
lithium cells, that nicads are still the way to go....  


/Brian

> The rechargeable lithium cells are going for about $25 per cell - or $100 for 
> your receiver pack!  No thanks.  My grandfather just picked up a set for one 
> of his ham sets, but the price will have to come WAY down before I'll 
> fly that kind of battery investment around!  He bought them from the same 
> out fit in Canada.  I got that poop sheet that your referencing also.

     OUCH!  $25/cell is a bit steep!  I sent for the info anyway.  I have
     been seeing the non-rechargeable lithium batterys for quite a while.
     About 1 to 2 years ago I read an article somewhere about the technical
     hurdles involved in making a rechargeable version and this issue of ECN
     was the first time I have seen a real product. With any kind of luck
     the price will drop as the manufacturing process and volume improves
     (I hope).

     Heavy sigh...

                     !
                   --+--
G. Schrader     o___<0>___o    CSS::SCHRADER
                  *  *  *

    My experience with these batteries is in memory backup.  They have
    a very long shelf life where as nicads self discharge rapidly. 
    I do not believe that they have a higher energy density than nicads
    and a couple hundred recharge cycles is 5 to 10 x less than nicads.
    The other factor would be internal resistance.  Nicads are very
    good for high discharge rates because they have a very low internal
    resistance.  This would not be a factor for receiver batteries but
    the only advantage over nicads that any battery could have would
    be energy density since weight is the name of the game in aircraft.
    It would be nice to have better batteries but I'm not going to hold
    my breath.  Development in this field has been very slow going.
    Other than packaging, we are using 30 year old technology in our
    cars and in our models.
    
    Charlie
    

    A friend sent me this, copied from Popular Science, W/O permission :
    
    
    Matsushita Electrics new cylindrical nickel-hybride battery has 50
    precent more storage capacity thatn a nickel- cadmium battery, and it
    can be recharged 500 times with no residual "memory."  According to the
    company, an AA-size nickel-hydride has a capacity of 1,070
    milliampere-hours (1.2 volts at 3 amperes) and it can be recharged in 1
    1/2 to 4 1/2 hours. 
 

ECN strikes again... The following blurb showed up on the front page:

NICKEL-METAL-HYDRIDE RECHARGABLE BATTERY FROM SANYO ENERGY
is a high-performance, high-capacity, cadmium-free cell which provides 1.8
times the energy density of conventional nickel-cadmium batteries. It offers
open circuit cell voltage of 1.0-1.3V/cell; discharge voltage of 1.2-1.25V/cell;
continuous charge time of 14-16 hours; and quick charge time of 1.5 hour.
Cycle life is 500 cycles at 100% depth of discharge. (address and contact
name deleted)

The picture that goes with the blurb shows what appears to be a AA cell
and a laptop PC overlayed on a tree (a envorinmental message related to
the lack of cadmium no doubt). Even if the mAH/oz wasn't any better than
a nicad it looks like it would make a dandy transmitter battery (assuming
that the price isn't in the stratosphere).

Anyway, has anybody run across these before? The cell characteristics look
about the same as nicad cells so they might even be direct substitues.

G. Schrader

    Yes, they've been talked about for some time now.  They have a
    significant MaH/Ounce advantage over NiCd cells.  The problem with them
    is that they're not rugged enough for the high rate discharges used in
    electric flight, and they charge slow, even at their "fast" rate.

    They are supposed to be Non-Toxic, though.

    IF, repeat IF, I remember correctly, they were discussed in one of the
    recent RC mags --- Oct, Nov, or Dec --- mag name forgotten, and the weight
    advantage is double that of NiCd, the cost [after the form feed]
    
    $180 per cell.

COUGH, COUGH, CHOKE, GAG, CHOKE, WHEEZE, WHEEZE, GASP, SAY WHAT!!!!!!!!

I think that $180 per cell is just a tad on the high side of my price range.
It's a shame that neat stuff has to be so darn expensive...

GS

    Give it time. The price will come down as production ramps up. Just
    think, you can get an individually crafted battery with a low serial 
    number and be the envy of your friends ;^)

    Actually, I recall the price was more like $180 for a 6 or 7 cell
    PACK.  That's MUCH more reasonable.  :-)  I think the article was in
    the electrics column of RCM.  

                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Castor Oil!! "    
                      |_____/

    I saw the article and it sounded like we should not get our hopes up
    too quickly.  Cost will be high for awhile and the batteries are not as
    durable and tolerant of high current charge or discharge.  Hopefully,
    the process will be improved and we will see the benefit of the reduced
    mah/oz without any major drawbacks.
    
    Charlie
    

    Any updates on the NiMH battery front. I saw some listed in the latest
    Tower catalog (AA's with/without tabs). Of course the Sanyo NiCd's are 
    on sale right now for $17.99 a 12 pack ($1.50 Each).