Battery types: Lead-Zinc
Alkaline
rechargeable
NiCd
Ni-Metal-Hydride
Gel lead/acid
Lead-acid
deep cycle
starting
Lead-Zinc:
Never plan to use standard lead-zinc batteries. These batteries have
neither the staying power/life or the instantaneous current delivery
required for radio work. However, if these are the only batteries
available they can be used. Lower your power and keep your transmission
as short as possible. If you have enough wire and batteries put them in
series/parallel to build up the voltage-(series) and the
current-(parallel) delivery. Never recharge these batteries. Contrary
to the "cheap" battery charger claims, these batteries can not be
recharged once used. This has to do with the chemistry of the battery,
it is not designed to go in reverse, so once the electrolyte is used it
forms a permanent new chemical which can not be broken back down to its
constituent chemicals by adding electricity back.
Alkaline:
These are much better to use than the lead-zinc batteries. They have
better life and better current capabilities. If you have an "empty"
battery case for your HT these batteries are an OK choice for it. They
are not quite up to the current demands of using an HT on full five to
seven watts output, but can handle about two or three watts. They have
a wonderful shelf life which makes them fantastic for emergency service
work. They will last up to three years sitting in a cool place, like
an emergency kit in the basement. The best version of these batteries
as measured by longer life are the Duracell batteries. This was
reported by Scott Rosenfeld, NF3I on the QRP-L e-mail reflector:
Ray-O-Vac Eveready Duracell NiCds Size Alkaline Renewal Energizer (GOOD ones) AAA 750 500 1100 1120 270 AA 2000 1000 2450 2450 600 (1000) C 5000 3100 7200 7100 2200 D 10000 5000 8900 14250 4400
Notice the difference in the D-cells. It looks like Duracell is the only one that truly makes a D-cell and not a C-cell packed in a D-cell case. Also, good AA cells have four times the expected AHr life of good NiCds!
The rechargeable version have all the advantages of the standard variety
except that they do not last as long in use. Only half as long as
Ray-O-Vac's own Alkaline and only about 2/5's as long as a Duracell or
Eveready. This is still almost twice as long as a NiCd. Last, you can
not build a simple charger for these batteries. You must use the
manufacturer's recharger, or build one using the chip set designed for
the purpose by companies like MAXIM.
NiCd: The reason NiCd packs die is that each cell is an individual with
different discharge/recharge characteristics "D/R-C". Eventually the
weakest cell is forced into reverse charging for extended periods and
the electrolyte is destroyed. This kills the pack. While you can
"save" the good cells, the probability is low that you will ever be able
to build your own pack from the leftovers from two or more packs
because of the need to closely match the cells in a pack. Cells are
selected for packs by the manufacturer in order to minimize the D/R-C's
between cells. The extent to which the company goes to match cells is
translated into the cost of the battery pack. At present there are
three or four grades of NiCd cell packs, they are; consumer grade,
professional grade, car/plane-hobby grade, and NASA grade. I'm not
real sure if the professional grade is any better than the consumer
grade (Ham radios) but the other two grades are substantially better
and more expensive. (NOTE: These "grades" are my own designations.) An
example may help understand the difference. NASA had turned off one of
its satellites and then a year later needed to turn it back on. It
"recharged" the battery pack and gave the command to wake up.
Everything worked fine and the battery pack was at 95% plus of new, and
this was after about five years of daily charging/discharging, close to
2000 recharge cycles. Just try that with one of our packs!
Disposal: You can now take these batteries to local Radio Shack and
hardware stores to be recycled.
Ni-Metal: Gel Cell/Lead Acid, all types: The liquid version can be recycled at a battery sales store. The Gel
Cells are also able to be recycled but I don't know where. I usually
take them to one of my former employers who recycles them. I know that
hospitals recycle the gel cells used in UPS's and other medical
equipment. This is also a good place to get used cells which still
have some life in them. Hospitals can not take chances and so they
change batteries out of medical equipment on a time basis.
The liquid version comes in two types, "deep discharge" (also known as
marine) and "starting". The starting battery is the one we have in our
cars. They must supply extremely high currents for short durations and
then get recharged quickly. (Starting currents are 40 plus amps, at 12
volts that's 480 watts.) The deep cycle batteries are the ones we want
to use for radio work. They will deliver the most power for the
longest time and be able to be abused a bit, left without recharging,
and still be usable. Most 100 watt rigs require 11 volts minimum to
operate well, so even if a deep cycle battery claims to be 70 AHr don't
expect to run your 100W radio on full transmission for four hours. If
you get half of the rated AHr rating you're doing very good.
I'll leave computing power usage calculations to a later date. But I
will give you a rule of thumb, if you run 100W on transmission, your rig
uses 200 Watts from the battery, two to one, and that's the best it can
do. Most times it's worse. Also, figure a 10% duty cycle, 10% transmit
and 90% monitor. You'll have to measure your rigs current usage while
monitoring.
Recharging: These batteries are all recharged in the same way, constant
voltage chargers. These are the typical car battery chargers available
almost everywhere. Or, you can make one with a 12V battery eliminator.
The small gel cells and small sealed lead-acid batteries usually have
the recharge instructions printed right on the case. For cyclic use
they can be charged to 14.0 - 15.0 volts, for backup use keep them
topped off at 13.5 - 13.8 volts.
The liquid type can be charged at much greater initial currents than the
deep cycle, the deep cycle can be charged at higher initial currents
than the sealed version, and the sealed version can be charged at
higher initial currents than the gel version.
I have designed a good "trickle" charger for these types of batteries.
I have been using a version of this charger for over ten years. I have
used the present version now for about two years on deep cycle, sealed
lead-acid, and gel cells with very good results. More information on
my charger design is available.
There are other types of batteries, but they are not yet ready for
general consumer use. I hope this helps you determine the best battery
or batteries to use for your emergency station and/or household use.
73 de KE3FL
These are used in every HT on the market. Some are just now being
replaced with the metal-hydride versions. But there are reasons that
may cause this to not be a universal replacement. This type of battery
can handle the instantaneous current demands of high-powered HT
transmitting with no problems. They do not last as long in operation,
as shown above, nor can they last unused "on the shelf." The shelf life
of standard NiCds used to be one month. By then the pack had lost a
third of its power. Todays standard NiCds seem to be better by almost
a month. This just seems to be the case from my own observations, and
may not be born out under study. Today's NiCds are better in their
expected power delivery, almost 50% better than just five to ten years
ago. One can build simple recharging systems for these batteries.
"Trickle-Chargers" however, there are limitations to this type of
charging and extended charging time will cause permanent damage to the
electrolyte. The new quick chargers are much better and more expensive.
To further extend the life of a battery pack you should disassemble it
and recharge each cell individually a few times every year or so. Some
reverse charging of each cell has been shown to be beneficial, causing
the recombination of gases into electrolyte. The reverse charge should
be of very short duration.
For more information about NiCd batteries see:
Some Ramblings about NiCd Batteries,
by: Ken A. Nishimura
These are similar to NiCds in all respects. The only place they are
worse is in their shelf life which as a rule of thumb is only half of a
standard NiCd. The other problem is that you need a special charger.
The advantage is that these pack more energy/weight than NiCds so the
battery pack is lighter and also lasts longer. Since they do not keep a
charge as long as NiCds do, you will need to charge them every
week or so and definitely do so before using them for an event. (Most
of us do this with our standard NiCd packs anyway.) These are not good
batteries to depend on for extended service during an emergency. These
would be good for the first week, after that switch to NiCds, and after
that use the Alkaline or lead-acid.
These batteries are so much alike that I'll simply state the
differences and then go from there. The Gel version can not supply the
level of instantaneous current that the liquid version can. The liquid
version is more dangerous due to the electrolyte being a liquid and a
highly corrosive acid. You never want to turn one of these batteries
upside-down because of the possibility of leakage.
Phil Karras, 9/1997
[Battery Charger, Trickle Charger Plus]
Designed by: KE3FL. Click on the hot area to read the technical paper.
Return to: KE3FL home page