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Question:

I recently returned from a live-aboard dive trip during which I blew up my only charger for my wide-angle strobe. Needless to say, this was very disappointing since I couldn't use my wide-angle lens except when I could borrow a strobe. Is there some way to check the current on the boat or to protect my charger to prevent this from happening again?

 

 

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Questions and Answers (Q & A's)

From Alan Broder (from Ocean Realm Magazine - May 1995)

Answer:

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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