Vertex Standard FT-60R Specifikace stáhnout pdf (Strana 8)

From February 2005 QST © ARRL

setup. The graph automatically adjusts

the vertical voltage scale and the horizon-

tal capacity scale to suit your test. The

CBA continues to draw the specified cur-

rent until the battery voltage drops to the

end voltage.

The CBA can dissipate at least 100 W,

higher for lower capacity battery packs.

If you try to set a test current that will

exceed the ratings, the software will

prompt you to reduce the test current to

a safe level.

I wanted to know how my 100 Ah gel

cell would compare to that rated capacity,

so I ran a test on the fully charged battery.

See Figure 6. With a 7 A load it has a ca-

pacity of about 88 Ah, down to 10.4 V.

I also tested a 17.2 Ah 12 V gel cell

that I have used to operate a 2 meter rig

for many of my Scout demonstrations

over the years. I recharged and tested this

battery several times, but it only seems

to have a capacity of about 1.2 Ah. I was

convinced this battery was better than

that, but after several tests I have con-

cluded that it isn’t providing as much

operating time as it should. It may be

well past time to replace that battery. I

also tested another old gel cell that didn’t

seem to be holding a charge very well.

Sure enough, the CBA indicates that bat-

tery is beyond any useful life.

To test some known good batteries I

decided to set up test fixtures for a few

other battery types.

A quick trip to RadioShack produced

a single AA cell holder that I clipped to

the Powerpole adapter cable to test some

AA cells. I have been using some NiCd

and NiMH cells for a variety of applica-

tions recently, and was curious as to how

Figure 6—The results of testing my pulled 100 Ah gel cell.

I set this test to draw 7 A from the battery. Notice that the test

stopped when the battery voltage dropped to 10.4 V. This

battery appears to have a capacity of about 88 Ah, rather

than the rated 100 Ah.

Figure 7—The results from three battery tests overlaid on top

of each other. The test compares a Sears DieHard alkaline AA

cell with two different NiMH AA cells.

they tested when compared to an alka-

line cell [note that testing the capacity

of a non-rechargable battery is a destruc-

tive test, but useful on a sample of a bat-

tery type—Ed.]. Figure 7 shows a graph

comparing three different AA cells.

Other Software Features

The CBA software has a number of

other very useful features. Obviously,

you can save each test graph for later

review. You can also overlay one test on

top of another. Figure 7 shows three such

graphs overlaid on each other. When you

overlay a test graph, the software color

codes each new graph, and also places a

color-coded legend along the right side

of the graph. If you have a color printer,

you can print the image in color. If you

only have a black printer, then the soft-

ware will add symbols to the lines and

legend to distinguish them from each

other.

The software also has a print labels

feature that helps you set up and print

labels to apply to your batteries. If you

have several similar packs, this is espe-

cially useful because it helps you keep

track of the individual packs. Rather

than always using the same one or two

packs, you can easily rotate the several

packs and use them uniformly. You can

also keep track of which packs are older,

so it is easier to decide when to test a

pack that may be getting past its useful

life. The label template is set up to use

Avery 05160 or equivalent label sheets.

How Often Should I Test My

Batteries?

That is an important question. If a re-

chargeable battery is good for a certain

number of charge/discharge cycles, then

every time you test the battery you can

subtract one from the remaining life of

your battery. Obviously, over testing is

not a good thing. West Mountain Radio

suggests that you run a test for a new

battery pack [especially good advice for

NiCd batteries—Ed.]. That will give you

a point of comparison as the pack ages.

They also recommend that you retest the

pack after it has been setting for some

time, or after it has been used a great

deal. I would probably err on the side of

not testing often enough rather than over

testing. West Mountain Radio says they

do not recommend testing or cycling bat-

teries if they are used regularly and seem

to be working well. That makes sense to

me.

Testing Accuracy

I used my digital multimeter (DMM)

as an ammeter to verify that the actual

load current was close to the indicated

test current. Within the accuracy of my

meter, I measured the same current as

the CBA. I also used the DMM to moni-

tor the battery voltage during a couple

of tests. Again, within the measurement

accuracy of my meter, the CBA software

was reporting the same terminal voltage.

The manufacturer reports that by our

publication date they will offer a CBA II

with higher resolution at low current.

Manufacturer: West Mountain Radio,

www.westmountainradio.com,18

Sheehan Ave, Norwalk, CT 06854; tel 203-

853-8080. Price: PWRgate PG40, $69.95;

Computerized Battery Analyzer, $99.95;

Temperature Probe for CBA, $10.95.

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