| You definitely are not the first to
"toast" a charger on a live-aboard dive boat, and
you certainly won't be the last. As a matter of fact, dive
boats are not the only ones to offer outlets you could plug
into at some considerable risk to your charger and/or your
battery pack. You can find the same violently virulent voltage
at hundreds of resorts and hotels all over the world. I refer
you to Murphy's Law #3791 - to wit, the better the diving,
the funkier the power. This is a corollary of the following
rule: The more remote an area is, the better the diving is
- and the more remote that area is. Power generated for large
populations with some real kind of budget is obviously larger,
better regulated, and less affected by individual users than
smaller generating plants growing on boats or supplying resorts.
If you're at a small resort generating its own power, the
total output of that generating system is very small when
compared to the type of systems supplying large populations.
When the resort's refrigeration system, air-conditioning (you
wish), or some other large power muncher comes on, there is
a drop in voltage due to the generator's inability to increase
its output quickly enough to keep the voltage constant. Recovery
may be almost instantaneous when the total output capacity
is large relative to the sudden demand or the demand is of
short duration. The lowered voltage condition ("brown
out") may persist if the total capacity of the generating
system is "currently challenged" or exceeded. When
the demand is suddenly terminated, the smaller generator's
output is reduced in a more unsudden manner, producing a "voltage
spike."
Let's put us in the position of the charger in a similar
circumstance. We are at a small motel and step into the shower,
select a temperature, then turn on the water. We are enjoying
our rejuvenation until some neighbor turns on his shower.
We've just been "browned out." We quickly adjust
the temperature and get on with our peaceful rebirth; however,
our neighbor is only into short showers. We've just been "spiked."
Since there's water present, we're par-boiled. In the charging
situation, which is hopefully a dry process, we're toasted.
Had we chosen a large hotel, the shower would have been more
satisfying. A nice spike (run-away high voltage) will tear
up your charger in a heartbeat, a brownout (drop in voltage
accompanied by a surge of current) can do the same number
- it just takes longer. Heat, in each case, is what destroys
the charger. Most chargers have a built-in thermostat to protect
against over-heating. Since both the charger and the batteries
normally heat up during charging, the thermostat also provides
the cue to let the charger know the battery is ready for service
and signals the charger to go into trickle mode when the feature
is provided. When a significant spike occurs, delicate components
in the charger, such as the windings in the transformer, heat
up instantaneously with a resulting breakdown in insulation
which will damage or destroy the unit. The thermostat won't
heat up fast enough to save the day, so the spike sneaks past
the sentry.
So now that you know more than you ever wanted to know about
generating systems and charges, I'm sure you will agree that
we should get to your questions. How do you protect against
all this? You might ask about the charging facility to find
out if it's dependable. Dependable on a small system means
well-regulated. Do they have a proper UPS (uninterrupted power
supply) which will maintain a constant voltage, ironing out
spikes and voltage drops by filtering and providing stored
energy? There are, however, several grades of quality found
in these units. Unfortunately, they all have the same name.
Testing voltage at the outlet with a voltmeter (even a cheap
minimeter from Radio Shack) will tell you if the juice is
about right, but obviously won't warn you of spikes, or phase
irregularities. It is possible that the current may be a little
high or low consistently, and this will affect your charging
rate as well as possibly jeopardizing your unit. Low output
from the generator can greatly increase the time needed to
charge your batteries, possibly beyond the duration of your
trip.
Consider bringing a backup (or possibly two); it may just
be your charger's time to pass on - we all gotta go someday!
If you think your charger is not working because your batteries
are never charged when you test them in the morning after
having them on the charger all night, check to see if someone
on the boat generally goes to bed after you do and gets up
earlier in the morning. To protect against the "cowbird"
syndrome, you can either stay up all night to be sure no one
is taking your charger off the strip and putting theirs on,
then switching back in the morning, or you can bring along
your own transformers to keep in your own room. This will
deter all but the most persistent of your fellow dive "buddies,"
unless you are not a particularly light sleeper.
How about the spike-protected outlet strips at the hardware
store for six bucks? You get six bucks worth of protection!
These work on a thermostat, and the thermostat doesn't react
- well, you know. You can buy more sophisticated and more
effective line protection with real filtration for as much
as seventy-five dollars or more, and it generally takes about
fifty to seventy-five dollars worth of protection to do the
job. These more expensive, larger and heavier units will handle
most of the problems encountered by most divers, but they
can be several times larger than your charger and will take
up a lot of space in your baggage.
So much for the bad news. The good news is that there are
a number of "smart" chargers coming on the market.
These chargers know whether they are looking at 110 (or so)
or 220 (or so) and will automatically adjust to the available
voltage. If you have a manually switchable charger and inadvertently
plug into 220 with the charger set at 110 - you blew it! The
smart chargers will also give you a significant level of protection
against aberrant current. Most computers and video chargers
use them; Nikon provides one (a la carte at about $400 retail)
for their SB104 strobe, and Ikelite has announced that they
will release one with their new Substrobe 200 later this year
for a little over $125. They will also offer a model for their
four-cell strobes. In addition to protecting its own integrity,
most models of this new breed of charger will deliver current
in pulses rather than at a constant rate, as do the "dumb"
chargers in current use today. This will keep the batteries
cooler during charging, achieving a deeper charge in a kinder
and gentler manner which not only will increase battery life,
but in some cases will recondition poorly performing cells.
Here are a couple of little tips for you in the event that
you do find yourself chargerless and in danger of becoming
a specialist in available light photography. Virtually all
of the chargers used today plug into 110V or 220V AC "wall"
current and put out DC at somewhere around six to twelve volts.
The level of current output is usually somewhere between one-half
amp and three or four amps. Check any chargers that you, other
divers, or the crew may have for various other electrical
appliances or tools. Your strobe charger will have its output
volts and amps marked on it. You may use a charger of similar
specifications to charge your strobe in a pinch. If the plug
is not right for your battery pack, cut off about a foot of
the battery end and wire the new one in, keeping the polarity
the same. If the substitute charger's output volts are higher,
or if it puts out a lot more amps than your own charger, your
batteries will charge faster than normally. When batteries
are being charged, they heat up. The faster they charge or
the closer in capacity they get, the hotter they become. Charge
until your batteries reach their proper voltage of about 1.35
or so per cell - about 5.5 for a four-cell pack. If you don't
have a volt meter, continue to charge until your batteries
become hot to the touch - hotter than warm but not hotter
than hell! If you're on a boat, there is a boat battery. If
you're on land, there are vehicles with batteries. You can,
if all else fails, charge your batteries from a boat or vehicle
battery by jumping positive to positive and negative to negative.
Since these mongo batteries are capable of delivering cranking
voltage in the hundred of amps range, careful monitoring is
definitely in order. You will have to charge your batteries
intermittently, removing a lead when the batteries become
hot and allowing them to cool a while. Repeat this form of
pulse charging until a meter reading indicates a full charge
or until the pack gets hot very quickly after hookup. This
is not a precise science, but you should be able to grab a
couple of rolls or better per charge. Expect to buy a new
battery pack when you get back, since your batteries were
probably not designed for his type of crash charging.
Underwater photography is very interesting - isn't it?
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