Great Lakes Singlehanded Society

A thousand pardons for not getting out a Rode Show in quite a while; I suppose it's a bit like single handing, in that events have to be prioritized from time to time, taking care of the major day to day items as they occur, and getting back to expanding into the hobbies as time and the eyeball size returns to normal. The Rode Show had to be put into the latter category for a while, things are working back to normal so onward we go. I had been talking some electrical systems, and left where the charging of said system was all that needed to be considered, so this one will tie up the last of the loose ends.

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Once you've dumped massive piles of folding money into a fresh set of gel or AGM batteries, you might as well check under the sofa cushions too and pick up a new shore side charger and a high output marine alternator with a "smart charger" regulator that has a built in charging curve to bring your batteries up to peak charge in the shortest amount of time. Smart charging consists of three stages, bulk, where charging up to around 75% of the capacity of your battery occurs, acceptance, where the next 25% of the battery is recharged, and float, where the battery is maintained at its maximum charge. If you have flooded lead acid batteries, there is a fourth charging level, equalization, which dissolves crystals of lead sulfate on the plates by upping the charging voltage to 15.5-16.2 volts. It's not done during every charging cycle, usually every 30-50 cycles; since the voltage is much higher than normal, it's important to disconnect any DC loads from the battery during the charging, or they may be damaged. Never, ever, ever equalize gel batteries, or the high voltage will do them in and you'll be scampering back to West Marine for another serving of them. Before the race, you'll want a freshly charged bank complements of shore side charging, and during it, engine charging. If you've come into your inheritance early, a genset with a mammoth output alternator/voltage regulator will allow you to be lit up like a freighter, run your air conditioner (just hate those hot days), play some Jimmy Buffett, and microwave to your heart's content without ever starting your engine. For the whole race.

When it comes to shore side charging, it pretty well boils down to one word these days, Xantrex. ProSine, Freedom, and Heart Interface all fall under the Xantrex umbrella, and all of the brands have the smart charging circuitry built in, have sophisticated surge protection, and if you were lucky enough to find a LOT of loose change under the cushions or hit the lottery, have inverters built in to power up that hair dryer enroute so upon arrival at the Island, you'll look your nattiest as you disembark at the docks. They can be output to second or third battery banks, and if they are of the pure sine wave variety, will run even the most sensitive applications such as computers, audio gear, and variable speed devices with ease. You can add just an inverter if you're happy with the existing charger, and it may be something as simple as a plug in pocket inverter that also works in cars, to a permanently installed 2000 watt variety. Needless to say, AC power is not free, and it's a good idea to have at least 20% of the inverter's rating in amp hours of battery capacity. Thus, that 2000-watt inverter just mentioned should be fed from a bank of at least 400 amp hours, or you will find yourself charging almost continuously as you microwave your middle of the night meal.

A good marine alternator and smart charge regulator will keep things quiet on the amp hour front while charging using the engine. Normal automotive alternators/regulators may work, but aren't designed to replace the large quantities of electricity used in marine applications, don't hold up to rigorous use nearly as well, and will commonly fail earlier. Try and use an alternator that will supply anywhere from 25-40% of the entire capacity of the bank you're trying to charge for the most efficient charging. Thus for a 500 amp hour bank, an alternator should be able to put out between 125 and 200 amps. Therein lies one of the rubs - trying to fit a large frame high amperage alternator into the engine space available, on a bracket available, with enough engine horsepower available to drive it efficiently. Small frame alternators range from around 55 to 150 amps, will work with a single belt, and are the easiest to fit into most existing engines. A good boat electrician or an insatiable appetite with a good "how to" book is a must for the large frame, two belt varieties, and helpful for their small framed brethren. It goes without saying that unless the batteries know how much is enough, the alternator will keep putting out the juice until the batteries fry; that's where the "smart" voltage regulator comes into play, and will efficiently charge the bank in the aforementioned stages without damaging the batteries. Even a simple solar panel charging system can damage batteries if allowed to continuously charge unregulated, as can wind generators.

As in knowing how much capacity is in the bank to start with, and how much you're using at any given time, it's just as important to know when it's back up. One of the simple monitoring systems such as a Link 10, or Link 20 for a two-bank system will let you know when the engine has charged the system up to a respectable level. It's really not practical to fully recharge the battery while motoring, as the last 25% takes a while. In most scenarios, batteries generally charge back to around 85%, and the time it takes to accomplish it will depend on how much they were drawn down, the output/charging RPM of the engine, and what the current load is while recharging.

Here's to a very fast race, minimal recharging (unless you love the smell of diesel in the morning), and enough juice in the battery bank to tell someone where you are at check in time.

Cheers
Tony Driza

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