what would cause all 12 volt systems on a boat to fail at the same time

12 Volt Electrical Systems

Battery Switches

The majority of boats on the h2o today depend on electricity to some degree. Unfortunately, too many of those boats are operating with inadequate and poorly installed electric systems. This can effect in unnecessary problems that drain your patience and bag and that tin can cause safety bug. A quick prepare may alleviate the problem for the brusk term, but if the organisation remains inadequate, problems will go on to plague information technology.

To begin taking the right steps to achieve a good electrical arrangement on your gunkhole you lot need to:

• Determine your power requirements
• Provide acceptable ability storage and starting chapters
• Provide the proper charging that you need
• Be sure your wiring is adequate and canonical for marine use and connections are sound
• Engage a qualified professional if needed
• Exist certain that all rubber requirements, such as the relevant ABYC standards, are met

Your boat'southward batteries are a cornerstone of a proficient electrical system. Power boats that are used simply to run from dock to dock on weekends may need just i (always ii are preferable) starting bombardment which we'll discuss beneath. These are less expensive and lighter than batteries designed for deep cycling, which is what y'all'll demand if y'all terminate for periods of time to anchor or drift or, far more importantly, if you plan to anchor overnight. Boats that are used for long term anchoring, as in serious cruising, need batteries capable of deeper discharges and of greater storage capacity. Such batteries include wetted lead acid, gel and AGM deep cycle types. However, even if yous merely plan to run from dock to dock or dock to fishing footing or beach and back, information technology'south of import to realize that you lot may be using electricity during those times that the engine is off and be prepared with the right type and size of batteries.

Batteries need practiced wiring to deliver the power supply to the gear onboard. That'due south the bailiwick of "Wiring". Since batteries are substantially fuel cells, charging the batteries is another important chemical element. For additional detail on that subject go to our Battery Chargers article. There are both DC (direct electric current every bit from 12 volt batteries) and AC (alternating current like what you use in your house) systems and issues on many boats, although some boats, particularly smaller ones, only use DC. Hither nosotros'll hash out primarily DC. AC options are discussed in some particular in the section "Inverters".

Determining Your 12-Volt Power Requirements

Starting time, calculate your daily (24-hour) average power consumption for all of the electric loads you place on your organization. List all of the appliances and their amp draws. If amps are not listed on the appliance, you can figure amps with the post-obit formula:

amps = watts / volts

Side by side, approximate the normal daily usage for each in hours, so that you take a list of appliances and their daily draw in amp-hours (Ah). Now full them all up. Only don't cut it shut. As bombardment voltage lowers with united states of america amperage describe will go upwardly. Also, amperage depict increases with wire run. This ways that the total of the power consumption numbers on your equipment will probably be less than your actual usage. For farther information run across the commodity on Inverters.

What Size Battery Do You Demand?

Let's assume your daily power consumption totals 100 Ah. A 100-Ah battery won't do information technology. Why? Because battery capacity is determined in part by the intervals between battery charges, and the discharge level. A 100-Ah bombardment might in theory run into your daily free energy requirements, but would take no reserve. And a battery should never be fully discharged. It must exist able to store and deliver the full 100-Ah between charges. Further, with each partial discharge of your bombardment its capacity will gradually diminish.

Automotive starting batteries are made for starting engines, with the quick release of a big burst of ability. They discharge simply about five percent, and are intended to exist immediately recharged by the alternator. They cannot handle the repeated deep discharges typical of marine use and they may suffer impairment from the constant pounding they receive at body of water. Conventional wet (atomic number 82 acid) deep cycle batteries or deep-bike gel cells or AGM batteries are best at withstanding the deep discharges, rapid high power recharging, and the concrete pounding of the marine environment. Look for batteries with the greatest number of life cycles at l% discharge and do not mix batteries of dissimilar construction type (such as, for example, wetted atomic number 82 acid and AGM) in the same depository financial institution - use ane or the other. There are also dual purpose batteries claimed to provide relatively loftier engine starting ability for their size but besides relatively adept deep cycling adequacy. (Don't count on these for cruising with repeated heavy deep cycling.)

Yous will possibly double the life of your battery if you don't discharge it beneath 50% capacity. Consider also, for instance, that lead acid batteries recharge chop-chop only up to effectually 70-lxxx% of capacity. If you don't want to spend a lot of time recharging that last 30%, plan on using just about thirty% of the bombardment'due south full capacity. And information technology's better to consume even less than that considering no battery operates at 100% over its total life. Also, give yourself a little power in reserve. Given all this you, in theory, will demand a 400-Ah wetted lead acid battery to meet your 100-Ah daily energy habit. In full general, a battery rated at four times your daily usage will be adequate. Only, as noted, this is only theoretical. Other factors, such equally, for instance, voltage drop (and therefore amperage increase) acquired by long wiring runs, volition affect the usage and size requirements. For further information see the article entitled "Inverters". If yous're thinking that all this sounds like a real drag; that you lot're going to need to exist canoeing with a computer to deal with batteries, relax. With expert modern battery chargers and alternators and a niggling mutual sense and observation on your function, your equipment will handle much of these problems. There's more on this below.

Battery Banks

Reserve an adequately-sized, fully charged battery or bank of batteries solely defended to starting your engine. Some prefer to use what are commonly referred to as "starting batteries" dedicated to engine starting. These typically have thinner plates just more plates and therefore can deliver more Cold Cranking Amps (CCA) for size and weight. CCA is the measure of how many amps the battery will supply to the starter motor for xxx seconds continuous at 0°F while maintaining its voltage to a higher place seven.2 volts. Marine batteries may also exist rated in Marine Cranking Amps (MCA) which is similar to CCA except at 32 degrees F. Starting batteries are typically not as tough in construction as batteries designed for deep-cycling and less expensive. These volition not serve well if you demand them for deep-cycling because such will rapidly deplete them, leading to early failure. A deep-wheel bombardment tin can be used for engine starting, as long as it provides enough cold-cranking amps (CCA) to hands get-go your engine.

Utilize a dissever bank of deep-cycle "business firm" batteries to supply the residual of the boat's electrical needs. Or, you can use two banks of deep-bike batteries, each with plenty cold-cranking amps to start the engine. Parallel the two banks with a dual-purpose bombardment isolation/selector switch for tough engine starts and then alternate between the two banks for "house" utilize. Always, nevertheless, keep one bank fully charged for starting.

Battery Charging

If y'all don't replace what yous employ, your batteries volition eventually become dead, no matter how much battery capacity you have on your boat.

The rate at which you tin can recharge your batteries depends on a number of factors including how much you discharged them, the condition of the bombardment, the temperature, the alternator'due south power (in amps) and its output (in volts) as well equally an AC bombardment charger'southward chapters and features.

Many boats accuse their batteries with an engine-driven alternator. If your engine running fourth dimension is minimal, you lot desire to accuse as quickly equally possible, without dissentious the battery. Battery impairment begins when the internal temperature becomes as well high, causing it to gas and oestrus upward. If information technology feels warm to the affect or if you're smelling gas, information technology'due south getting too hot. A smart voltage regulator for the alternator should control and taper off the charge to forestall this and can also be ready, within limitations, to arrange your needs. More than on this below.

The marine alternator is generally more suitable for use on a boat than the typical automotive alternator sometimes found as original equipment on new gas and diesel engines. Alternators are typically rated in amps; the rating refers to the maximum output in ane hr at a certain temperature and rotation speed. Typical automotive alternators can't run continuously at full load in the warm temperatures establish around boat engines, or in warm climates. Further they have internal voltage regulators that are prepare to deliver a rapid charge to a starting battery, non to deliver sustained tapered intelligent deep cycle recharge for house batteries. A suitable marine alternator may be rated at total continuous load at temperatures up to 200°F. Some marine alternators take special grease in the bearings and other special construction to withstand the college running temperatures and loads every bit they proceed to put out at college levels during deep bicycle recharging. They are also more robust in many other respects.

A good dominion of pollex is that y'all volition need at least 120% of the energy you used to restore the battery. And to prolong the life of your alternator, plan on running it at less than full output. Take into business relationship any other power-draining loads yous might be adding to the system as yous are recharging, such equally refrigeration or inverters. If you install an oversized alternator, you can recharge efficiently while at ballast, with the engine at idle and the alternator operating below its rated speed and output. (However, it isn't helpful to the engine to run information technology for long periods of time under low load. Many prefer to charge batteries while at ballast using an AC generator and AC battery charger. More than on this below.) Again, a "smart" regulator which you tin can set to perform optimally for your parameters is needed.

The speed of your alternator'south rotation is a role of engine RPMs and your alternator'due south pulley wheel size. Once you lot have determined the maximum alternator output you require, add around 25% or more then you won't have to operate it at full diameter to achieve the required results. Now bank check how many alternator RPMs it takes to attain that output. Then make up one's mind the minimum engine RPMs at the engine'south ability take off wheel at which you will be charging. You need a caster ratio that gives you maximum required output at your minimum engine speed. If you lot need 110 amps, and it takes an alternator RPM of 4,000 to generate it, and your engine is running at ane,000 RPMs, then you demand a 4:1 pulley. Make certain that if you punch your engine up to iii,000 RPMs, thereby increasing your alternator speed to 12,000, you are not exceeding maximum safe alternator speed. Typically, the manufacturer of a expert marine alternator should provide this information for your application and besides the alternator pulley wheel that you demand.

Voltage Regulation

A voltage regulator determines the charge per unit and mode which an alternator or Air conditioning charger will charge your battery. Normally nosotros think of voltage regulators specifically for alternators, but even Air conditioning chargers have internal components that determine rate and manner of accuse. In better units these internal components can be field adjusted. If charging isn't done properly your batteries can endure failures ranging to total depletion to overheating, gassing and substantially self destructing.

The basic alternator voltage regulator maintains voltage at a certain level past matching alternator output with the load and the charge level of the battery. Voltage drops when a load is placed on the power system, or when the battery discharges. The regulator and so increases the amperage output of the alternator until the voltage level is restored, and so tapers output to a level that will sustain that voltage.

Y'all should have a regulator that is external, and field adjustable, and then that you can adjust the alternator's performance, tailoring the alternator's output to the type and size of battery(south) that you are charging. A "smart" voltage regulator tin can likewise be prepare to accuse specific types of batteries in a way that volition not merely charge them well, but also requite them longer life. A practiced marine adjustable smart voltage regulator should exist able to charge at 3 stages, oftentimes called "bulk, absorption and bladder." Bulk puts a lot of ability into the battery rather fast, to bring information technology up rapidly to a sure point. And then the regulator will switch to absorption mode before the battery gets too hot or gasses or becomes otherwise damaged. At absorption, charging occurs more slowly to provide more than subdued charge commiserate with the state of charge of the battery. Once the voltage is at the desired level the regulator shifts into float which essentially maintains the battery, making adjustment for usage. Some regulators even take rut sensors on the depository financial institution(south) so that they can compensate for that gene. Of form all of this must exist set for the parameters of your battery and/or bank. Different sizes and different types (such as lead acid, Gel and AGM) of batteries require dissimilar types and rates of charging, as well as different voltage levels. Usually instructions with the voltage regulator will help you with this.

Your 12 volt organization tin can also exist used to supply AC current, similar you lot have in your house, with the addition of a marine approved inverter which will capsize the DC current (ordinarily obtained from your battery bank) to Ac. For further information see our article on Inverters.

Inverters increase the load on the bombardment and bank size and alternator charging must compensate for this. Of form, the greater the Air-conditioning draw from the inverter, the greater the inverter'due south DC describe from the battery. Also, as the inverter is converting at higher amps, its efficiency volition diminish, again causing higher rate of battery depletion. This makes it even more important to accept a robust marine alternator controlled by an external adjustable voltage regulator. With suitable equipment, you tin can use AC current while you are running and continue the batteries topped upward. If the battery banks are large enough for your consumption and properly charged, yous can have quiet times at ballast with AC ability bachelor without running the generator all the time.

There are now Ac powered bombardment chargers on the market that tin charge and maintain not only unlike banks but as well banks that have different construction techniques, such as wetted lead acrid, gel and AGM. These essentially jump from bank to depository financial institution in sensing and do what's needed for that depository financial institution. Of course, yous must ready these up appropriately for your system. When you charge your batteries when AC is bachelor (from the dock or from an onboard marine generator) through a battery charger, it should be rated for marine use and also have "smart" charging with similar charge settings and charge characteristics discussed in a higher place as to the alternator'due south voltage regulator.

With multiple bombardment banks many people adopt to take a device which automatically shifts charging output to different banks then that no one depository financial institution is overcharged. However many prefer to monitor bank status manually and use a battery selector switch to direct charging current to the advisable bank. Failure of automated devices, frequently hidden away in an engine space, tin result in improper charging leading to discharge or overcharge which volition "cook" a battery, ruining it, and which could cause explosion or emission of big amounts of corrosive explosive gas.

Wind and Solar Charging

Many people likewise utilise air current generators and solar cells to keep their 12 volt system charged. Solar cells generally have less output for the coin than current of air generators and require special mounting racks or cabin or bimini peak space. Wind generators can commonly put out more than electric current, but only if the air current is upwardly. They make noise, which some observe objectionable but others discover soothing. Unremarkably people go accepted to information technology. Great care must be taken to avoid being hit by a propeller and also to shut it down when the wind gets likewise high. Better wind generators have a self contained automatic dampening machinery to forestall over-speed in loftier winds. 1 or both systems are often used by those who don't consume much electricity or who want to go on their batteries up while they're off the gunkhole, particularly equally when in that location's no dock power available as when they're at anchor or on a mooring. Fifty-fifty with these systems you must provide overcharge protection. Devices that do this usually come up with the current of air generator or solar jail cell.

We tin can only scratch the surface of this subject, which could easily make full a large volume. If you want to be easily on (and that'southward good) read some of the many books on the subject. In whatsoever issue, it never hurts to involve a well trained competent professional when dealing with any kind of electricity on a boat.

Technology, knowledge and practices change nigh daily therefore it is prudent to research for the very latest up to the appointment data and seek qualified professional assistance when needed.

Author

BoatUS Editors

Contributor, BoatUS Magazine

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Source: https://www.boatus.com/expert-advice/expert-advice-archive/2012/july/12-volt-electrical-systems

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