As our own sailboat had battery problems (dead) and wiring connection issues requiring the replacement of essentially the entire setup, it was beneficial to research the internet for regulatory requirements, recommendations, and best practices.  A review of different battery manufacture's websites, their battery types, and their installation manuals increased our perspective of what might constitute a proper system and installation.  The USCG/CFR regulations were reviewed, ABYC recommendations (E-10/11) were reviewed, and numerous self-proclaimed marine electrical guru websites were checked for pertinent information. Books and magazine articles were read.  The amount of information and advice freely available is staggering. It was interesting to discover what these sources all agreed upon and what they emphasized to different degrees - it was also telling to discover what they didn't discuss versus another site that did.  Opinions here varied widely from what type of battery was the "best" and was cheapest in the long run, to almost every detail to support the battery installation.  It was easy to spot the natural manufacture's biases and the bias of people's experience - you can't teach old dogs new tricks philosophy.  What required thought, was the attempt to separate the facts from fiction, opinions, and biases.

A few websites of currently cruising folks were reviewed for how they approached their battery installation, maintenance, and how often they needed replacement.  Each website came across with their own assertion of expertise in this area of knowledge and backed-up their assertions with how long their batteries lasted under their maintenance regimes.  Hard to challenge what worked for them based off of years of experience and their satisfaction with their results.  The confidence in their knowledge and pride of workmanship was portrayed in pictures and videos posted to their website, social account, or video channel.  Their comment sections, in almost all cases, had praise and accolades flowing from folks that took the time to comment and exhibited arm-chair admiration for the website, persons, and/or the concept of sailing/cruising. Some of the comments with praise came from folks claiming electrical/engineering degrees, marine certifications, certified surveyors, or XX-plus years of been-there-done-that experience.   Based on what was narrated on the website with pictorial evidence and the praise and concurrence of suspected knowledgeable and experienced readers, one would most likely "assume" the information and knowledge divulged was gospel - reliable.

However, a detailed review of the factual pictorial evidence presented as gospel yielded surprising insights and revelations. The following pictures are from a cruising website with 30-plus years of out there, doing it, hands-on experience.  And yes, I actually enjoy and respect their perspective - but sitting aside egos, pride, and admiration, the pictorial facts reveal another story.  These folks are die hard advocates of the keep-it simple-stupid philosophy and assert the more involved and complex systems are a drain on the cash balance sheet.  They are strong advocates of the time tested, liquid lead acid battery technology; and it has satisfied their desires and needs; and they claim over time for the least outlay of cash.  A check on the price of the Trojan T-105 revealed they could cost $125.00 with core exchange, so six of these could run a total of $750.00.  They weigh 62 pounds (28 kilos) each, so this battery bank weighs about 372 pounds (168 kilos) in total. The 225 Ah batteries are connected in series-parallel for a total of 675 amps house battery bank.  A picture from there website dissertation showing use of Trojan T-105 6-volt batteries that last 9 to 10 years on average is shown below.

To objectively evaluate their installation of Trojan T-105 6-volt batteries the Trojan Battery User's Guide was downloaded and reviewed.

The picture above clearly reflects noncompliance with the manufacture's instructions below.

The battery orientation in this installation is bow-to-stern.  Advice on the internet for flooded batteries is to orient the battery installation port-to-starboard, to minimize electrolyte leakage and exposure of the positive and negative plates at angles of heel.

Almost all sources reviewed agreed on the principal that heat degrades all the different types of batteries available; and adequate ventilation and airflow was extremely important to minimize the negative effects of heat on battery lifespan. Adequate ventilation was also important in removing the corrosive, toxic, and potentially explosive hydrogen gas that batteries emit particularly for flooded batteries while charging or deeply discharging, but still applicable to GEL or AGM - but to a lessor degree.  What was surprising on the issue of ventilation was the inconsistencies of what adequate airflow meant - some advised passive airflow (vents, holes, etc.) was sufficient; while a very few advised active airflow (fans) was needed - not one source provided factual requirements of the amount of airflow needed to achieve "adequate".  Additionally, since the battery gases emitted during states of charging and higher levels of discharging are corrosive, toxic, and potentially explosive (hydrogen), some advised these gases should be channeled outside the boat via a hose and vent system, while others stated the passive venting into other compartments was sufficient - as most boats strive to achieve a structure that is watertight (and therefore almost airtight) this advice did not seem well thought out from a safety point of view.  A percentage of the sources advised to keep these gases away from electrical devices due to corrosive issues, ensure the gases are not routed to living spaces due to its toxicity, and many strongly advised to keep the gases away from any potential sources that could spark an explosion due to hydrogen gas issues.  Strict regulatory guidelines mandating forced and passive airflow schemes were established for boats with gasoline engines to reduce potential explosions/fires from gas fumes and these rules had the unintended added benefit of providing a path for the dispersion and exit of any battery gas emissions; but these regulatory guidelines were not applicable to diesel engine equipped boats. Something didn't pass the commonsense test here - why such a stringent standard for gas fumes, but no clear definition addressing battery hydrogen gas or even propane - are standards based on potential safety issues or bureaucratically experienced tombstone catastrophes.

A check of boating accident statistics for fire related causes yield zero cases attributed to lack of venting battery hydrogen gases - not one!  Maybe this is truly a nonissue.  Per these statistics, about 35  percent of fires were attributed to the 12-volt DC system and over half of these were related to both the engine and battery compartments of which almost all were attributed to faulty wiring and connections.  A further review of a few of the specific boat fire accident insurance reports revealed most causes were not really factual but "suspected" as the fire destroyed any definitive evidence.  So in most of these cases the opinion of the investigator was taken as plausible and factual, based on their years of experience and training.  What was interesting in many of these suspected faulty wiring or connection related fires was the lack of evidence if proper overcurrent protection was even utilized or not.  After reviewing these reports, really could not counter the conclusions, as they were possible, but equally so, in many of the cases, could not rule out the possibility that battery hydrogen gas emissions were not a contributing factor.

The National Electric Code (NEC) Handbook (Note the NEC is not applicable to watercraft ref 90.2.B.1) says that mechanical ventilation is not required for enclosures of battery systems. Convection ventilation is permitted. Hydrogen disperses rapidly and requires little air movement to prevent accumulations. Unrestricted natural air movement in the vicinity of the battery, together with normal air changes for occupied spaces or heat removal, will normally suffice. If the space is confined, mechanical ventilation may be required in the vicinity of the battery. Hydrogen is lighter than air and will tend to concentrate at ceiling-level, so some form of ventilation should be provided at the upper portion of the structure. Ventilation can be a fan, roof ridge vent, or louvered area.  In most cases, battery storage boxes and battery installation locations on boats can be reasonably classified as confined spaces.

ABYC standards for section E-10 Storage Batteries states:  10.7.9 - A vent system or other means shall be provided to permit the discharge from the boat of hydrogen gas released by the battery.  10.7.10 - Battery boxes, whose cover forms a pocket over the battery, shall be vented at the uppermost portion of the cover.

None of the sources reviewed provided a clear, definitive answer to the question of how much airflow is needed to remove heat or explosive gas (particularly during a equalize charge condition) to an adequate level.  By sheer chance, found a internet page with a Hydrogen Gas Ventilation Calculator for Battery Rooms.  Also a website with the computation formulas was found. Using the picture above with Trojan T-105 6-volt liquid lead acid batteries, input the following into the calculator:

• Step 1 - Number of Cells in Battery = 3 and 6-Hour Rated Capacity of battery in Ampere-Hours = ~190 revealed Volume of Hydrogen produced per hour during recharge = 0.42 cubic feet.
• Step 2 - Room Volume (for a room with a flat roof - used estimated measurement of battery box above) - Width = 2 feet, Length = 2 feet, and Height = 1 feet revealed Total Volume of Room = 4 cubic feet.
• Step 3 - Hydrogen Gas Produced per Hour = Volume of Hydrogen = 0.42 ft. (Result from Step 1) and Number of Batteries Stored in Room = 6 Trojan T-105s revealed Hydrogen Gas Produced per Hour = 2.52 cubic feet.
• Step 4 - Ventilation Requirement = Volume of Room = 4 cubic feet (Result from Step 2) and Hydrogen Gas Produced per Hour = 2.52 cubic feet (Result from Step 3) and Max. percentage of hydrogen gas allowed = 1% (Industry Standard) revealed Complete Air Exchange Required Every 0.95 minutes.
• Step 5 - Fan Requirement = Volume of Room = 4 cubic feet (Result from Step 2) and Complete Air Exchange Every = 0.95 minutes (Result from Step 4) revealed Fan Requirement = 4.2 cubic feet per minute.
• Step 6 - Percentage of Hydrogen Gas = Hydrogen Gas Produced Per Hour = 2.52 cubic feet (Result from Step 3) and Total Volume of Room = 4 cubic feet (Result from Step 2) revealed Percentage of Hydrogen Gas = 63.01 %

In step 2 above, the room (battery box) volume empty is 4 cubic feet, but with 6 Trojan T-105s actual air volume is closer to about 1.2 cubic feet.  The above calculator was rerun with the reduced air volume and the Complete Air Exchange Required was every 0.29 minutes and Percentage of Hydrogen Gas was 210.05 % with the other values remaining the same. While this computation is not 100% accurate since it is based on many assumptions and estimated values, it is probably not far off from realistic requirements, and is a bit more informative than just stating adequate airflow.  It also leads to the conclusion that batteries mounted in a battery box and/or installed in a confined space with just passive ventilation might not be sufficient to circulate airflow to sufficiently minimize hydrogen gas emissions levels during charging and equalizing operations.  This computation does not address adequate airflow for heat dissipation issues, but more airflow is definitely better than none or less (passive) in this case.

Back to the website dissertation showing installation of Trojan T-105 6-volt batteries.  The battery box they use has four holes on the front side for airflow entry - however the battery installation does not appear to have the recommended 0.5 inch clearance and most likely the batteries forward side location being almost directly against the wood structure is restricting airflow entry from these holes.  The battery box cover is not fully closed as the aft edge is exposed to allow room for the inverter and cable routing - not ideal as this could allow entry of water and objects that could potentially short the unprotected exposed battery terminals.  The entryway ladder rests on top of the battery box cover, so this installation is potential exposed to water intrusion from the companionway entrance located directly above - not an ideal location.  The battery box airflow is dependent upon passive airflow and its exit point is directly below the inverter - not ideal as corrosive fumes can degraded electronic components.  Additionally this exit point for potentially toxic fumes is into living spaces - not an ideal healthy situation.

The Code of Federal Regulations (CFR), 33 CFR 183.420.(a) - Batteries states: "Each installed battery must not move more than one inch in any direction when a pulling force of 90 pounds or twice the battery weight, whichever is less, is applied through the center of gravity of the battery...".   While the CFR requirement is an enforceable law, the applicability as stated in 33 CFR 183.401, states this requirement applies to all boats that have gasoline engines, except outboard engines, for electrical generation, mechanical power, or propulsion - this boat only has diesel engines; so the CFR requirement is really not applicable.  The ABYC standards which are supposedly voluntary, E-10 Storage Batteries, section 10.7.4, recommends this same requirements.  Check of the manufacture's manual states battery must be kept in an upright position but does not include guidelines for secure battery mounting practices.  The picture above showing the Trojan T-105 6-Volt Battery House Bank reveals the batteries are only positioned in the battery box without any means to secure them in place.  In the event of extreme boat heel angles, a knockdown, or a capsize this installation and lack of method to secure the batteries in place, most likely will lead to making an already bad situation an extremely hazardous situation.

Next, a very detailed look at the battery cables and terminal connections revealed another set of issues.

In the following picture (lower right red arrow pointing upwards) highlights where the cable enters the lug terminal; the color of the wire reveals it is plain stranded copper wire.  While plain stranded copper meets the requirements of 33 CFR 183.425.(a), accepted marine best practices/recommendations advise use of tinned (silver color) stranded copper wire due to its corrosion resistance properties.  The middle red arrow pointing down highlights a poorly executed hammer type crimp and lack of adhesive lined heat shrink to seal the terminal to cable connection from corrosion.  The left red arrow pointing down highlights a greenish material caused by battery acid caustic effects - the terminal lug needs cleaning.  This terminal connection is also lacking the application of corrosion prevention spray as recommended in the manufacture's manual.

ABYC standard, E-10 Storage Batteries, section 10.8.3 states, Battery cables and other conductors size 6 AWG (13.3 mm²) and larger shall not be connected to the battery with wing nuts.  In the picture below, the top red arrow pointing downward highlights the ill-advised use of a wing nut.  The middle red arrow pointing left highlights a greenish colored battery lug in need of cleaning and corrosion prevention spray.  Also the position of the aft portion of the terminal lug with the metal circular entrance for the cable appears to be positioned over the battery circular terminal "dam" which potentially would make it difficult to obtain proper flat contact of the terminal lug under the wing nut.  The bottom red arrow pointing right highlights the lack of  adhesive lined heat shrink to seal the terminal to cable connection from corrosion.  Lastly, this cable terminal lug does not appear to be crimped, but possibly a solder only connection.

The manufacture's manual under the Safety section states: Always use largest cable size of shortest length to minimize voltage drop.  In the Cable Size section it further states: In series/parallel battery banks, it is preferable for all series cables to be the same length, and all parallel cables to be the same length.  In the picture below the two red arrows highlights that the battery series interconnect cables are not the same length as recommended.  A close inventory of the battery cable lugs reveals they are of different size, material, and crimp/solder connections - almost all are in need of cleaning and corrosion prevention treatment.  As the black battery cables have none of the required manufacture identification markings and they are also non-tinned copper strand type wire, it is reasonable to suspect the cables are not rated for the marine environment or in compliance with USCG or ABYC recommendations.  CFR, Title 33, Chapter I, Subchapter S, Part 183.420.(b) states: Each battery must be installed so that metallic objects cannot come in contact with the ungrounded battery terminals. No provisions to comply with this requirement is evident in the pictures shown.

Another experienced long time cruiser posted a picture of their battery installation to their social account.  They had purchased four Lifeline GPL-8DL 12-volt, 255AH batteries.  These weigh 156 pounds (70.2 kilos) each with combined weight about 624 pounds (283 kilos).  Check of pricing showed they cost about $586.00 each, or total cost of about $2,344.00.  The four 255 AH batteries were connected in parallel for a total bank size of 1,020 amps.  Their issue was after being installed for about 5 months and in constant daily use, their charge capacity appeared diminished, and they were asking if equalizing might help.  They stated their last Lifeline battery bank of 660 Ah lasted more than five years and they never had to equalized them.  When queried if they were fully charging the batteries back up, they stated they were on top of it. Yet on another query, they stated they had charging issues with their solar/wind charge controller potential affecting the batteries, and they had to use their portable 2000 watt generator to compensate. Lastly a reader commented that another very experienced and knowledgeable cruiser had two different sets of Lifeline AGM batteries that died after 2 short years. This cruiser obtained a third set of Lifeline batteries and with direct Lifeline support guidance learned the value of following the manufacture's instructions on equalization - the battery bank was reported to have lasted 5-plus years.

We wanted to know more about the story of this very experienced and knowledgeable cruiser that had two different sets of Lifeline AGM batteries that died after 2 short years. We read the following excerpt from the Lifeline website.

We followed the website link "www.morganscloud.com" and it open up a site called "Attainable Adventure Cruising" - a pay to access content website.  As we wanted to "know more" we signed up for a year and had access to the content - in reality the content is a series of blog posts organized by subject matter, some into what they term online books. We read the online book section on Battery Installation & Maintenance, all 19 chapters, but the "root" cause of two sets of AGM battery bank failures was not clear. We posed a very direct and blunt question: "Was part of the battery issues experienced here simply a failure to follow manufacturer’s printed instructions?" We did not get a direct yes or no answer, just a statement, "...I have certainty never claimed I did not make mistakes." The Lifeline battery manual instructions were not followed - just as mentioned above for the other cruiser; there is a stubborn resistance by many to just simply read and follow instructions - why?  It was dumbfounding as to why Lifeline provided a customer another set of new AGMs knowing full well there was negligent in the required maintenance of the batteries as stipulated in the manual. We were equally unimpressed on the dirty secrets of alternators blog post – evil factory default settings.  Each alternator we have used comes with a manual that in detail explains how to customize it for your unique conditions on your boat – but only if you’re willing to READ and FOLLOW the instructions – again this was not the case.  A separate post showed a newly installed Maus fire extinguisher (not USCG approved) next to their existing Badger model 5MB-6H standard ABC multipurpose dry chemical extinguisher. The Bager (2005) and all his other extinguisher (2004) were overdue mandatory replacement due to being over 12 years old [NFPA 10 7.3.6.3]. When we commented on this, again it was not directly addressed.  We did not renew our subscription on this site - not our cup of tea.

Downloaded the Lifeline Technical Manual from the internet and reviewed it. The Lifeline manual installation instructions paragraph 5.2 stated: "Be sure there is adequate ventilation in the area where the batteries are to be installed.  Refer to section 6.1 for specific safety hazards associated with the emission of hydrogen gas. The space surrounding adjacent batteries should be at least 0.25 inch to permit airflow around each battery."  The manual stated its battery capacity ratings were based on use at an optimum temperature of 77 F degrees (25 C) and battery lifespan decreases by 50% for every 10 C degree rise in temperature - i.e. 95 F degrees (35 C).  Just like the Trojan manual, the Lifeline manual does not elaborate on what adequate ventilation means, but emphasizes increased heat degrades battery life.

The picture below depicts the installation of their four Lifeline GDL-8DL AGM 12-volt batteries.  While the quality of the picture doesn't allow for expanded zoom to clearly view the installation in detail, certain observations can still be made.

• The arrangement of the batteries does not appear to provide the recommended spacing for proper airflow.  No airflow entry points are visible on the sides and the slatted wooden berth rack with mattress on top is not conducive for airflow.  Loose pieces of wood and a cutlery board stowed on top of batteries will not aid airflow and stowage of other items with batteries is not recommended.
• The batteries are not secured down in place as required by USCG and ABYC recommendations.  The slatted wooden berth rack has no visible method to secure it down to the structure below.  Imagine what 624 pounds (283 kilos) would do if a knockdown or capsize happen - would you want to be on that berth in that situation?
• The ungrounded battery terminals are not protected or isolated to prevent potential shorts. The slatted wooden berth rack with mattress on top still provides a possible entry point for objects.
• The battery cables are connected in parallel but are not all the recommended same length to reduce imbalance conditions.
• Two red cables are connected to positive terminals and appear to lack the overcurrent fuse protection per the 7"/40"/72" ABYC E-11 rules.
• The two red and one yellow cables that provide external connection are not properly secured to prevent movement/chaffing and no cable strain relief is provided at the battery L-blade terminal which could result in terminal or case breakage.

While the issues with the physical installation of the batteries are not optimum, they do not really account for the reported problem of capacitance loss.  Review of Lifeline's Technical Manual section 5.4 Charging, did state a reason that mimicked the problem reported:  If the recharge is insufficient, the battery's state of charge will gradually "walk down" as it is cycled, resulting in sulfation and premature failure.  The manual contained very detailed instructions on how to recharge the batteries and also steps to ensure the full charge state was obtained.  In the event full charge was not being obtained, the manual provided a method to compensate for this, a conditioning or equalization charge. The manual Rev E, page 21 recommended routine conditioning charge is applied approximately every two to four weeks if batteries are not fully recharged each cycle. The battery charge rate had very detailed and specific instructions for temperature compensation, this coupled with temperature sensors on most modern chargers of all types, seems to emphasize that "adequate airflow" for heat dissipation might be just a little more important than assumed.

In Lifeline's Owner Manual, Document No. 6-0104 Rev B, a brief 4-page booklet that is included with each battery sold; in section Conditioning/Equalizing Charge it states:  "Charge at 15.5 volts for 8 hours.  Conditioning/equalizing should only be done when the battery is showing symptoms of capacity loss. If conditioning/equalizing is necessary, first go through the normal charge cycle. Once the battery is fully charged, start the conditioning/equalizing charge.  NOTE: For maximum life, the batteries must be periodically recharged to 100% capacity. Continually recharging to less than 100% may result in premature capacity loss. It is recommended that batteries be recharged to 100% at least every 5-10 cycles."

The Lifeline Technical Manual also alluded at "other factors" that degrade lifespan:  "The charging current during the Bulk stage should be set as high as practical; higher current levels mean faster recharge time and less time for the plates to become sulfated."  "...Lifeline batteries can tolerate in-rush current levels as high as 5C (500A for a 100Ah battery)."    So for a battery bank size of 1,020Ah made of 255Ah batteries and in-rush current of 5C, theoretically 1,275 amps input would be ideal.  Did not find one source on the internet that had installed a charging system with this level of charge capacity.

The Lifeline Technical Manual alludes even further:  "For repetitive deep cycling applications (deeper than 50% DOD), chargers should have an output current of at least 0.2C (20 Amps for a 100Ah battery). If the output current is less than this value, the cycle life of the battery may be negatively affected."  So for a battery bank size of 1,020Ah made of 255Ah batteries and minimum charge rate of 0.2C, theoretically a charger with 51 amps minimum charge rate is needed.  Did not find on the internet a solar array or wind generator system installed on boats that would consistently meet this minimum charge requirement.

It is reasonable to conclude that the charging system requirements for use with AGM batteries needs to be considered and with an increase in the amp hour size of a AGM bank of batteries, the charging system capacity needs to increase to meet the increased charging current requirements to achieve maximum AGM battery lifespan.  As this cruiser had a previous 660 Ah AGM Lifeline battery bank that lasted "just shy of 6 years" and admitted they never equalized them as required by Lifeline's maintenance instructions that would have added more to their lifespan;  it is reasonable to assume that it is very likely their charging system or method is not up to par to handle their new 1,020 Lifeline AGM battery bank.

As the Lifeline batteries had been installed and used for 5 months, and were exhibiting adverse symptoms with an equalization charge just now being considered, one can reasonably conclude the Lifeline's Technical Manual instructions were not being followed. As advised by many, proper maintenance is very important, and detailed record keeping is more than just written dates and facts, if properly done, it allows you to detect adverse trends early and correct them.  Detailed record keeping on battery performance indicators might be a valuable practice.  If the battery full charge status was determined by diligently performing/recording the recommended open circuit voltage measurement, a minor change in diminished capacitance could be detected and corrective conditioning/equalizing charge applied to maximize the reduction of plate sulfation.

These revelations of the benefit of high amp charge rates and charging systems have other implications.  The size of the battery interconnect cables was recommended to be designed for the max load of the system, it seems this is not clearly defined, as load can be interpreted as discharge provided amps.  The size of the battery cables should be as large as practical to support an adequately designed charging system, seems a more clearly defined requirement.  As the 4/0 AWG cable is the most common large cable size available and has an average ampacity of 360 amps, this might become the limiting size for charging capacity design, at least for the most common 12 volt systems.

There are many considerations one must negotiate to determine the ideal battery system to install aboard.  One must review the regulatory requirements and manufacture recommendations closely.  Also there is ample lessons to learned by critically reviewing what others have done - right or wrong.