House battery banks continue to grow as onboard accessories multiply. A bank of batteries like these flooded-cell Rolls units may approach 1,000 amp-hours.
The list of battery types, sizes and configurations is nearly endless, from nonrenewable flashlight batteries to the latest nickel-metal-hydride rechargeables that are used to power cell phones, laptops and hand-held VHFs. For the purposes of the average voyager, the quest for reliable, powerful and affordable deep-cycle house and start batteries takes precedence over all other battery interests. Even this considerably narrower category presents a dizzying prospect for the would-be battery purchaser. Available configurations run the gamut from flooded to gel and absorbed glass mat (AGM), from 6-volt traction to dedicated 12-volt marine. How is a cruiser to know what is appropriate for his or her needs? It’s beyond the scope of this article to provide minute detail on each battery type, size and brand. However, an understanding of battery basics, as well as an assortment of maintenance and installation techniques, will assist the cruising skipper in making an informed decision that will offer the most value for his or her battery acquisitions. Battery basics
While there are three primary types of batteries available for cruising vessels today — flooded-cell, gel and AGM — all fall into two categories: deep-cycle or cranking. It’s important to understand the differences between these before delving into a discussion about subtypes.
House batteries are designed to provide moderate power over long periods, such as those required by a cruising vessel at anchor or under sail. Lights, electronics, communications, pumps, etc. all rely on the house battery bank for power when no charge source is available. In order to supply these demands properly, a true house battery, which by definition must be deep-cycle, is made up of fewer, thicker plates, compared to other battery types. Capacity in this type of battery is directly affected by cubic inches or volume of the plates. This design allows for repeated discharges and recharges that range from hundreds to thousands of cycles.
While thick-plated house batteries are capable of supplying starting current when called upon to do so, they are less than ideal when used in this role. Many house battery banks serve admirably in the role of starting batteries; however, to do this, they must often be physically larger than a comparable dedicated starting battery. Many deep-cycle batteries that are capable of supplying adequate starting loads are characterized as dual-purpose.
Starting or cranking batteries are specifically designed for the converse, providing a great deal of power over a very short period, which is exactly what a properly operating starter/engine combination calls for, a five-second or less jolt of hundreds of amps. In order to do this, these batteries use a greater number of thinner plates. It’s the surface area rather than volume of the plate that delivers high bursts of cranking amps, which are well suited to the Herculean task of starting a diesel engine.
Unlike house batteries, cranking batteries are incapable of playing the dual role of start and house load supplier. They are not designed to be heavily discharged like house batteries, for the volume of the plate, its innards essentially, supplies long doses of moderate amperage. For example, the average engine start may only discharge a cranking battery by 5 percent of its amp-hour capacity, whereas a house battery is routinely drawn down by 40 percent or more. If you place a start battery in the role of the house battery, expect a short life indeed, perhaps fewer than 50 discharge and charge cycles.
Familiar flooded cells
The flooded, or wet, cell is among the most ubiquitous of all battery types. Until just a few years ago, the only choice involved answering two questions, from which manufacturer and in what size would this battery be purchased? Flooded batteries possess the distinct advantage of having been around for a long time. Their strengths and weaknesses are well understood. Additionally, their design and manufacturing process has been anything but static. Improvements and modifications continue to be made on a regular basis.
Without going too deeply into the chemistry of the process, flooded batteries use a combination of free electrolyte, in the form of sulfuric acid, and plates made up of lead dioxide and a lead alloy grid. The battery case contains these components to a degree. If you’ve ever been unfortunate enough to drop or tip over a conventional flooded battery, you know that the electrolyte is only held within the battery by gravity, a force that is sometimes in flux aboard a cruising vessel.
Additionally, when this type of battery is charged, the by-products are hydrogen and oxygen. The former is a liability in an enclosed space, such as a cruising vessel’s cabin, in that it is explosive in concentrations greater than about 4 percent. Thus, all battery compartments must be ventilated properly. (Sealed batteries such as gel and AGM are also subject to this rule because, while they don’t vent hydrogen under normal circumstances, they are capable of doing so under some conditions.) The hydrogen and oxygen (the component ingredients of water) must also be replaced periodically, which requires that the battery be accessible for inspection and “watering.”
The disparity in quality between flooded batteries varies from manufacturer to manufacturer and, not surprisingly, by cost. Although not a hard and fast rule, the old axiom of getting what you pay for usually applies where batteries are concerned.
A few features to look for when purchasing flooded batteries include plate-separator material. Higher quality batteries often use synthetic materials like polyethylene, while economy batteries may use impregnated cellulose or paper. In addition, the plates of any quality battery destined for marine use must be encapsulated in three-sided envelopes. These envelopes reduce the effects of shedding, an inevitable process where active material falls off the plates. While enveloped plates may continue to shed, the material is contained and thus prevented from causing an internal short circuit. Batteries that go to sea are particularly susceptible to this, thanks to the agitating effects of wave-induced motion.
Finally, although not definitive, weight is often an indicator of a battery’s capacity. The heavier of two batteries in the same case size will often outperform its lighter brethren. This is a result of the quantity of active material — lead — used in a given battery’s construction. As mentioned, the more volume used, the greater the capacity. Because cranking batteries rely on plate surface area rather than volume, this rule of thumb is less relevant when making comparisons.
Gel cells
Gel batteries, sometimes referred to as sealed-valve-regulated, or SVR, batteries, gained a great deal of popularity a decade or so ago, thanks to several attributes. The most notable of these is their ability to charge very quickly; they are maintenance-free and spillproof. As the name implies, these batteries immobilize their electrolyte in a silica-based gel.
While they are capable of being charged very quickly, gel batteries are particularly sensitive to overcharging. Most modern shore-powered chargers and alternator regulators offer built-in profiles for gel batteries. Early in their introduction to the marine market, many gel batteries failed shortly after being placed into service. The primary cause for these premature failures was improper charging. A shore charger or alternator regulator that offers a gel-charging profile must charge gel batteries, even those used in starting applications. This fact is often overlooked where a stock, internally regulated alternator charges start batteries. The result — which is exacerbated by the fact that start batteries usually experience shallow discharges — in this case, is nearly always diminished battery life as a result of chronic overcharging.
Initially designed for the military and civil aviation industry, AGM batteries are also classified as SVR because they are also designed with sealed, maintenance-free cases. The valve that is referred to in this description, for both AGMs and gels, is designed to open if the pressure within the battery’s case exceeds a preset limit because of overcharging. If the valve opens, hydrogen gas is vented, which is why even sealed batteries must be installed in ventilated compartments.
AGMs share some attributes with gel batteries in that they are able to accept comparatively quick charge rates, which makes them attractive to cruisers, because this equates to less engine run time. AGMs tend to be somewhat less sensitive to overcharging than gels; however, they also have a specific AGM profile for charging in order to achieve maximum performance. Additionally, every battery — flooded, gel and AGM — will benefit from temperature-compensated charging, a feature available on many shore-powered chargers and alternator regulators. Simply put, cold batteries can accept a higher charge voltage than warm batteries. Temperature compensation takes advantage of this phenomenon, ensuring that batteries are not over- or undercharged because of their temperature.
Critical battery terminology
Battery capacity is measured in several different fashions. The most popular of these are cold-cranking amps (often abbreviated as CCA), reserve capacity and amp-hours, or simply capacity. For the voyager, cold-crank amps and amp-hours are the most relevant of the three. Reserve capacity, more an automotive than marine rating, is simply the number of minutes a battery will sustain a 25-amp load (roughly what a set of incandescent headlights draws, although this figure may vary from manufacturer to manufacturer) at 80° F, until the battery’s charge descends to 10.5 volts. The variations on these themes are many and varied; thus, it is critical to ensure like criteria when comparing batteries.
The CCA rating is the most critical figure to consider when purchasing a starting battery. It will tell you how many amps a battery is capable of delivering for 30 seconds, much longer than the average engine crank period, at 0° F, until a 12-volt battery’s voltage drops to 7.2 volts. Because few cruising vessels are started in this manner, a healthy reserve is usually available if a battery is selected based on the engine manufacturer’s requirements. Nearly all engine manufacturers specify the required CCAs for a given engine; however, in the absence of this information, approximately four CCAs per horsepower (on a 12-volt system) may serve as a rough guideline.
Some battery manufacturers use a marine cranking amp, or MCA, rating rather than the more familiar CCA. MCAs are measured at 32° F rather than 0° F, so they are always greater when compared to CCAs in the same battery. Once again, when making comparisons, don’t be misled by these differing standards.
Cold-cranking amps take a back seat to amp-hours where deep-cycle batteries are concerned. As mentioned, these batteries, by virtue of their plate construction, are designed to deliver moderate amperage over an extended period. The amp-hour capacity is usually based on the 20-hour standard and is a measure of the energy delivered by a battery over this duration. Therefore, a battery with a 100-amp-hour capacity is capable of delivering five amps for 20 hours. Be cautious when comparing amp-hour ratings, some calculations are based on an eight-hour standard.
Sizing
Integrating battery-bank size, load and charge is a vital yet often-overlooked prerequisite in designing a vessel’s DC electrical system. For several reasons, the ideal range of use for marine deep-cycle batteries involves discharging by 40 or 50 percent and recharging to 80 or 85 percent of capacity. While the explanation for this guideline could fill an entire article, the brief version involves charge efficiency and obtaining the maximum number of amp-hours balanced against the number of cycles obtained from a given battery bank. Discharging batteries by much more than 40 or 50 percent shortens their life considerably. Attempting to recharge these same batteries much beyond 80 or 85 percent usually requires an inordinate amount of engine run time (replacing this final 15 or 20 percent is achievable without placing undue stress on the system when a shore-power charger is used, provided it is allowed to run for a long enough interval).
Alternator/battery-bank sizing
Added to this equation is the proper relationship between alternator and battery-bank size. The rule of thumb in this case is that alternator output should be approximately 25 percent of the house bank’s capacity. Higher is better; however, flooded batteries are incapable of accepting much more than 25 percent of their amp-hour capacity in alternator output, where gel and AGM batteries are capable of higher charge rates and thus benefit from higher output alternators. For example, an alternator that has an output of no less than 100 amps when hot should charge a 400-amp-hour battery bank. Adding amp-hours to this equation in the form of more batteries, in an attempt to extend the intervals between charging, will only serve to increase charge times, which usually leads to chronic undercharging. If, for logistical reasons, this is the largest alternator you can use on your engine, then your battery bank should not exceed the 400-amp-hour mark. If you want more amp-hours, then you must supply the bank with a larger or additional charge source (such as another alternator, solar panel, wind generator, etc.).
Bank sizing follows its own rule of four times the average daily load, although this must be subordinate to the aforementioned charge source size. Therefore, if your vessel and its crew draw an average of 100 amps over a 24-hour period, the house battery bank should be approximately 400-amp-hours or greater.
The final factor to consider when designing a battery bank is its actual configuration. Gone are the days of two equally sized banks and selector switch, where one was used and the other remained in reserve. Today’s charging and battery technology, along with hard-won wisdom in the marine electrical, electronics and cruising communities, calls for a single, large house bank and a dedicated yet completely separate start battery, and never the twain shall meet unless an emergency dictates otherwise. The house bank receives the bulk of the charge, as it should, and the start battery can be charged by a device that siphons fully regulated charge current from the start bank — rather than using a simple overcharge-prone paralleling solenoid. Alternatively, on systems opting for additional redundancy, the start battery may use its own alternator (with the properly profiled regulator). In the event of a house alternator failure, this system offers the capability of being paralleled with the house battery bank.
A secure installation
Although last in this discussion of marine battery installations, the importance of security cannot be overemphasized. The American Boat & Yacht Council’s (www.abycinc.org) recommended standards for battery installations allow for up to 1 inch of movement of the battery case subsequent to installation. However, the ideal battery installation completely immobilizes all batteries, thereby reducing the likelihood of chafe or loosened connections. This can be accomplished by using purpose-made battery boxes or trays.
Battery installation kits consisting of light-gauge, mild steel fasteners and plastic buckled straps are better suited to inshore runabouts than offshore voyaging vessels. A proper battery installation should either use through-bolted or heavy, long stainless-steel tapping screws. In the event of a knockdown or inversion, the batteries and the shelf to which they are attached, must not be allowed to come adrift.
Other battery installation considerations include a requirement for containment of spilled electrolyte, in the form of a tray or box. The fasteners securing such a tray must not be exposed to spilled acid, which means the screws or bolts may not be located inside the containment area. Additionally, batteries must not be installed directly above or below a fuel tank, fuel filter or fuel-line fitting, and they may not be installed directly below a battery charger or inverter.
Additionally, battery positive terminals and exposed cell straps must be insulated to prevent accidental shorting in the event they come in contact with the vessel’s DC ground. A wrench, for instance, dropped across a battery’s terminals may cause heavy arcing, which could lead to fire or explosion.
Finally, use caution when attaching cable terminals to battery posts. Avoid using metals other than copper for high-amperage connections. Stainless steel and brass, for instance — which are only 5 and 28 percent as conductive as copper, respectively — will present paths of high resistance to battery current. A particularly insidious yet all-too-common scenario involves the placement of a stainless-steel washer between a cable’s ring terminal and the battery post. Under heavy current draw, this washer’s high resistance may cause it to become extremely hot, which could instigate combustion. This is why nothing should be stored in battery compartments except batteries.
Properly designed, installed and maintained marine battery banks will provide thousands of amp-hours and years of economical, reliable service.
Contributing Editor Steve C. D’Antonio is a freelance writer and the boatyard manager of Zimmerman Marine in Mathews, Va.
Without going too deeply into the chemistry of the process, flooded batteries use a combination of free electrolyte, in the form of sulfuric acid, and plates made up of lead dioxide and a lead alloy grid. The battery case contains these components to a degree. If you've ever been unfortunate enough to drop or tip over a conventional flooded battery, you know that the electrolyte is only held within the battery by gravity, a force that is sometimes in flux aboard a cruising vessel.
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Too many connections at the battery terminals make for an unreliable installation. Attach a number of heavy cables using a high-amperage buss bar. Additionally, when this type of battery is charged, the by-products are hydrogen and oxygen. The former is a liability in an enclosed space, such as a cruising vessel's cabin, in that it is explosive in concentrations greater than about 4 percent. Thus, all battery compartments must be ventilated properly. (Sealed batteries such as gel and AGM are also subject to this rule because, while they don't vent hydrogen under normal circumstances, they are capable of doing so under some conditions.) The hydrogen and oxygen (the component ingredients of water) must also be replaced periodically, which requires that the battery be accessible for inspection and "watering."
The disparity in quality between flooded batteries varies from manufacturer to manufacturer and, not surprisingly, by cost. Although not a hard and fast rule, the old axiom of getting what you pay for usually applies where batteries are concerned.
A few features to look for when purchasing flooded batteries include plate-separator material. Higher quality batteries often use synthetic materials like polyethylene, while economy batteries may use impregnated cellulose or paper. In addition, the plates of any quality battery destined for marine use must be encapsulated in three-sided envelopes. These envelopes reduce the effects of shedding, an inevitable process where active material falls off the plates. While enveloped plates may continue to shed, the material is contained and thus prevented from causing an internal short circuit. Batteries that go to sea are particularly susceptible to this, thanks to the agitating effects of wave-induced motion.
Finally, although not definitive, weight is often an indicator of a battery's capacity. The heavier of two batteries in the same case size will often outperform its lighter brethren. This is a result of the quantity of active material &mdash lead &mdash used in a given battery's construction. As mentioned, the more volume used, the greater the capacity. Because cranking batteries rely on plate surface area rather than volume, this rule of thumb is less relevant when making comparisons.
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This two-year-old gel battery suffered premature failure as a result of severe overcharging.Gel cells
Gel batteries, sometimes referred to as sealed-valve-regulated, or SVR, batteries, gained a great deal of popularity a decade or so ago, thanks to several attributes. The most notable of these is their ability to charge very quickly; they are maintenance-free and spillproof. As the name implies, these batteries immobilize their electrolyte in a silica-based gel.
This cutaway illustration shows how an absorbed glass mat (AGM) battery from Optima Batteries is constructed. Properly monitored, AGM batteries can accept a high rate of charge.
While they are capable of being charged very quickly, gel batteries are particularly sensitive to overcharging. Most modern shore-powered chargers and alternator regulators offer built-in profiles for gel batteries. Early in their introduction to the marine market, many gel batteries failed shortly after being placed into service. The primary cause for these premature failures was improper charging. A shore charger or alternator regulator that offers a gel-charging profile must charge gel batteries, even those used in starting applications. This fact is often overlooked where a stock, internally regulated alternator charges start batteries. The result &mdash which is exacerbated by the fact that start batteries usually experience shallow discharges &mdash in this case, is nearly always diminished battery life as a result of chronic overcharging.
Initially designed for the military and civil aviation industry, AGM batteries are also classified as SVR because they are also designed with sealed, maintenance-free cases. The valve that is referred to in this description, for both AGMs and gels, is designed to open if the pressure within the battery's case exceeds a preset limit because of overcharging. If the valve opens, hydrogen gas is vented, which is why even sealed batteries must be installed in ventilated compartments.
AGMs share some attributes with gel batteries in that they are able to accept comparatively quick charge rates, which makes them attractive to cruisers, because this equates to less engine run time. AGMs tend to be somewhat less sensitive to overcharging than gels; however, they also have a specific AGM profile for charging in order to achieve maximum performance. Additionally, every battery &mdash flooded, gel and AGM &mdash will benefit from temperature-compensated charging, a feature available on many shore-powered chargers and alternator regulators. Simply put, cold batteries can accept a higher charge voltage than warm batteries. Temperature compensation takes advantage of this phenomenon, ensuring that batteries are not over- or undercharged because of their temperature.
Once an SVR battery ventilates because of overcharging or overheating, the lost material, essentially water, can never be replaced. Thus, if repeatedly overcharged, SVR batteries will fail in short order. Carefully follow battery manufacturer guidelines to ensure that the charge regimen delivered is ideally suited to the battery being used. Don't assume that the charger or regulator is properly profiled for your batteries. It is advisable, at least initially, to confirm the output at each charge stage with a digital voltmeter. Thereafter, periodic checks of the three charge cycles &mdash bulk, acceptance and float &mdash will serve to ensure proper operation of the system and maximum battery life.
Critical battery terminology
Battery capacity is measured in several different fashions. The most popular of these are cold-cranking amps (often abbreviated as CCA), reserve capacity and amp-hours, or simply capacity. For the voyager, cold-crank amps and amp-hours are the most relevant of the three. Reserve capacity, more an automotive than marine rating, is simply the number of minutes a battery will sustain a 25-amp load (roughly what a set of incandescent headlights draws, although this figure may vary from manufacturer to manufacturer) at 80� F, until the battery's charge descends to 10.5 volts. The variations on these themes are many and varied; thus, it is critical to ensure like criteria when comparing batteries.
The CCA rating is the most critical figure to consider when purchasing a starting battery. It will tell you how many amps a battery is capable of delivering for 30 seconds, much longer than the average engine crank period, at 0� F, until a 12-volt battery's voltage drops to 7.2 volts. Because few cruising vessels are started in this manner, a healthy reserve is usually available if a battery is selected based on the engine manufacturer's requirements. Nearly all engine manufacturers specify the required CCAs for a given engine; however, in the absence of this information, approximately four CCAs per horsepower (on a 12-volt system) may serve as a rough guideline.
Some battery manufacturers use a marine cranking amp, or MCA, rating rather than the more familiar CCA. MCAs are measured at 32� F rather than 0� F, so they are always greater when compared to CCAs in the same battery. Once again, when making comparisons, don't be misled by these differing standards.
Cold-cranking amps take a back seat to amp-hours where deep-cycle batteries are concerned. As mentioned, these batteries, by virtue of their plate construction, are designed to deliver moderate amperage over an extended period. The amp-hour capacity is usually based on the 20-hour standard and is a measure of the energy delivered by a battery over this duration. Therefore, a battery with a 100-amp-hour capacity is capable of delivering five amps for 20 hours. Be cautious when comparing amp-hour ratings, some calculations are based on an eight-hour standard.
Sizing
Integrating battery-bank size, load and charge is a vital yet often-overlooked prerequisite in designing a vessel's DC electrical system. For several reasons, the ideal range of use for marine deep-cycle batteries involves discharging by 40 or 50 percent and recharging to 80 or 85 percent of capacity. While the explanation for this guideline could fill an entire article, the brief version involves charge efficiency and obtaining the maximum number of amp-hours balanced against the number of cycles obtained from a given battery bank. Discharging batteries by much more than 40 or 50 percent shortens their life considerably. Attempting to recharge these same batteries much beyond 80 or 85 percent usually requires an inordinate amount of engine run time (replacing this final 15 or 20 percent is achievable without placing undue stress on the system when a shore-power charger is used, provided it is allowed to run for a long enough interval).
Alternator/battery-bank sizing
Added to this equation is the proper relationship between alternator and battery-bank size. The rule of thumb in this case is that alternator output should be approximately 25 percent of the house bank's capacity. Higher is better; however, flooded batteries are incapable of accepting much more than 25 percent of their amp-hour capacity in alternator output, where gel and AGM batteries are capable of higher charge rates and thus benefit from higher output alternators. For example, an alternator that has an output of no less than 100 amps when hot should charge a 400-amp-hour battery bank. Adding amp-hours to this equation in the form of more batteries, in an attempt to extend the intervals between charging, will only serve to increase charge times, which usually leads to chronic undercharging. If, for logistical reasons, this is the largest alternator you can use on your engine, then your battery bank should not exceed the 400-amp-hour mark. If you want more amp-hours, then you must supply the bank with a larger or additional charge source (such as another alternator, solar panel, wind generator, etc.).
Bank sizing follows its own rule of four times the average daily load, although this must be subordinate to the aforementioned charge source size. Therefore, if your vessel and its crew draw an average of 100 amps over a 24-hour period, the house battery bank should be approximately 400-amp-hours or greater.
The final factor to consider when designing a battery bank is its actual configuration. Gone are the days of two equally sized banks and selector switch, where one was used and the other remained in reserve. Today's charging and battery technology, along with hard-won wisdom in the marine electrical, electronics and cruising communities, calls for a single, large house bank and a dedicated yet completely separate start battery, and never the twain shall meet unless an emergency dictates otherwise. The house bank receives the bulk of the charge, as it should, and the start battery can be charged by a device that siphons fully regulated charge current from the start bank &mdash rather than using a simple overcharge-prone paralleling solenoid. Alternatively, on systems opting for additional redundancy, the start battery may use its own alternator (with the properly profiled regulator). In the event of a house alternator failure, this system offers the capability of being paralleled with the house battery bank.
The house and start banks should also be equipped with their own, dedicated battery disconnect switches as well as a manual parallel switch that will enable interconnection of the two banks for emergency starting or charging purposes. It is preferable that the disconnect switches be located as close as possible to the battery banks and outside of the engine compartment. Locating a main battery disconnect in an engine compartment is tantamount to installing a fire extinguisher over the galley stove. In the event of a fire (statistics show that most onboard fires originate in the DC electrical system), the vessel's crew must be able to open these switches quickly and easily in order to remove the heat source from an electrical blaze.
A secure installation
Although last in this discussion of marine battery installations, the importance of security cannot be overemphasized. The American Boat & Yacht Council's (www.abycinc.org) recommended standards for battery installations allow for up to 1 inch of movement of the battery case subsequent to installation. However, the ideal battery installation completely immobilizes all batteries, thereby reducing the likelihood of chafe or loosened connections. This can be accomplished by using purpose-made battery boxes or trays.
Battery installation kits consisting of light-gauge, mild steel fasteners and plastic buckled straps are better suited to inshore runabouts than offshore voyaging vessels. A proper battery installation should either use through-bolted or heavy, long stainless-steel tapping screws. In the event of a knockdown or inversion, the batteries and the shelf to which they are attached, must not be allowed to come adrift.
Other battery installation considerations include a requirement for containment of spilled electrolyte, in the form of a tray or box. The fasteners securing such a tray must not be exposed to spilled acid, which means the screws or bolts may not be located inside the containment area. Additionally, batteries must not be installed directly above or below a fuel tank, fuel filter or fuel-line fitting, and they may not be installed directly below a battery charger or inverter.
Additionally, battery positive terminals and exposed cell straps must be insulated to prevent accidental shorting in the event they come in contact with the vessel's DC ground. A wrench, for instance, dropped across a battery's terminals may cause heavy arcing, which could lead to fire or explosion.
Finally, use caution when attaching cable terminals to battery posts. Avoid using metals other than copper for high-amperage connections. Stainless steel and brass, for instance &mdash which are only 5 and 28 percent as conductive as copper, respectively &mdash will present paths of high resistance to battery current. A particularly insidious yet all-too-common scenario involves the placement of a stainless-steel washer between a cable's ring terminal and the battery post. Under heavy current draw, this washer's high resistance may cause it to become extremely hot, which could instigate combustion. This is why nothing should be stored in battery compartments except batteries.
Properly designed, installed and maintained marine battery banks will provide thousands of amp-hours and years of economical, reliable service.
Contributing Editor Steve C. D'Antonio is a freelance writer and the boatyard manager of Zimmerman Marine in Mathews, Va.
