[Icom] RE: Lithium Battery Pack..?

[Hsu, Aaron]

My 2 cents on batteries...

NiCd - Nickle Cadmium - The old standby.
Pros:  Most number of recharge cycles of the common "rechargable" types.
Low internal resistance lends to higher discharge rates (good for "high
power" uses).  OK tolerance for over charge/discharge.  Many more "types" of
cell construction suited for different purposes (fast/rapid
charge/discharge, high heat, "rugged" use, etc).  Can be charged with a
simple circuit (most all battery chargers on the market can charge a NiCd).
Fairly low self-discharge rate.
Cons:  Lower capacity than other cell types.  "Memory" effect.  Internal
cell shorting.  In my experience, shorted cells are the number #1 cause of
cell failure.  Cadmium is a toxic metal and must be properly disposed.
General: Actual number of recharges usually limited by care and condition of
cell.  Treat it well and it will serve you until internal shorts start
"growing".  Even then, a "zap" will give you a few more cycles.  IMHO, good
for high-cyclic, short duration, high duty-cycle use (e.g.  Radios used
constantly for a few hours at a time.)

NiMH - Nickel Metal-Hydride - The new "king"?
Pros:  High number of recharge cycles.  Fairly low internal resistance.  No
memory effect.  High energy/weight ratio.  Can be recharged with low-current
NiCd chargers.
Cons:  Less tolerant to overcharge/discharge.  Higher internal resistance
than NiCd causes cell to heat up more than NiCd during high-current "bulk"
charging.  As such, NiMH chargers usually monitor temperature of cell while
charging.  Less recharge cycles vs NiCd.  More expensive vs NiCd (for now).
General:  Good replacement for NiCd's in most applications.  Make sure to
get a NiMH-suitable charger (e.g. deltaT, -deltaV) for high-current charging
due to heat generation.  Low-current NiCd chargers work fine with NiMH.
Best when used in moderate draw, constant current applications like digital
cameras, portable audio, etc.

Li-ion - Lithium Ion - Lotsa power in small packages
Pros:  Very high energy/weight ratio.  Certain cell chemistries (e.g.
Li-Polymer) allow for "moldable" cells (new PDA's and TabletPC's will use
Li-Polymer cells where the battery is "squeezed" wherever there's space).
Very low self-discharge rate.
Cons:  More expensive than NiCd/NiMH.  Lower number of charge/discharge
cycles vs NiCd/NiMH.  *HIGHLY* intolerant to overcharge and heat.  Highly
intolerant to 0v discharge, but may recover.  Failed cell not as easily
replaceable as NiCd/NiMH.  Not available in "standard" sizes (e.g.
AAA/AA/C/D) and for good reason - 3.6v per cell.  
General:  3.6v per cell *requires* different charger than NiCd/NiMH.  Due to
this, Li-ion battery packs may not work with older radios that have built-in
chargers.  Also, each cell in a pack must be monitored individually.  Great
for devices that require high energy/weight ratios - digital cameras,
camcorders, high-tech electronics (laptops), etc.

All of this info as gathered over the past few years.  I'm under the weather
as I type this, so I may have left out some details here or there.
Corrections are welcome.

73,

  - Aaron, NN6O

p.s.  Oh, NiCd/NiMH are 1.2v nominal and are considered fully discharged at
1.0v.  Li-ion are fully discharged when they reach 2.7v.

-----Original Message-----
From: Chris BONDE [mailto:ve7hcb@rac.ca]
Sent: Saturday, March 22, 2003 11:20 AM
To: icom@mailman.qth.net
Subject: RE: [Icom] Lithium Battery Pack..?


I am mixed up.  You say use lithium, then give references to NiMhd
batteries.

What are the costs of lithium?  Can they be charged with the metal hydrid 
type charger?  What voltage do they give?  (I understand that all the 
different types give a different voltage.)

I am starting to change to Metal Hydrides as the NiCd batteries give up.

Chris opr VE7HCB


At 03:21 PM 2003-03-22 +0000, you wrote:
> > Subject: [Icom] Lithium Battery Pack..?
>
>You could do what I did.  I bought two BP-170 battery packs.  I put some
>1850 mah NiMH batteries in them.  The original BP-173 batteries were
lasting
>me 4-5 hours at 5 watts output.  Instead of NiMH, use lithium.
>
>Here is how it worked.
>
>BP-173  5w out, 650 mah nicd            lasts 4-5 hours
>BP-170  1.5w out, 1850 mah nimh         lasts 24+ hours
>
>The lower power was a problem.  I have never done a measurement, but I
>imagine the stock rubber duck is -3dB. (Maybe worse?)  So the 5 watt output
>gets me 2.5 watts ERP. (Maybe less?)
>
>I changed antennas.  I now use the comet BNC-24.  They claim 2.1 dB gain.
>This takes the 1.5 watt BP-170 output to around 2.5w ERP.  One note, I did
>add some heat shrink to stiffen the BNC-24 a bit.
>
>So now I can hike two days on one battery pack instead of changing
batteries
>every few hours.  Additionally, every item I carry on my pack, GPS, strobe,
>flashlight, all use AA batteries.  So I carry less spares as they are
>interchangeable.  Longer life, less weight, and same ERP.  It couldn't be
>better, unless they invent a battery that weighs 1 oz, and runs 5 years on
>air!
>
>Mike.  KD9KC
>El Paso, TX.


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