My third letter to Chuck Husick and Ocean Navigator
As promised, it remains unansweredWritten in the winter months of 1999. Later corrections added in [blue]. Mr. Husicks response to my second letter is highlighted in red
Editors of Ocean Navigator, Mr. Queeney, Mr. Husick,
I have read with great interest Mr. Husicks latest response to my letter to the editors. I value Mr. Husicks responses, just as long as he does not criticize the work of other authors without providing proof why his arguments are better. For instance, Mr. Calders Boatowners Manual was dismissed as mere "opinions" and none of my references were apparently queried. This was not the professional reply I envisioned. In the following long response to Mr. Husicks letter I will illustrate why Ocean Navigator should take greater care reviewing his work prior to publication.
We can agree on Surrette/Rolls being a manufacturer of premium deep cycle flooded cells - at least the 400 and 500 series. I propose the comparison of the 400 and 500 series vs. Lifeline advanced AGMs manufactured by Concorde. Perhaps you have additional data for deep cycle batteries that you can add to the discussion.
1. I appreciate your agreeing regarding the ultimate life of flooded verses AGM or Gel batteries.
My response was abundantly clear: The published data suggests that some premium deep-cycle flooded cells will survive more discharge cycles than AGMs, but the vast majority of flooded cells will not. Even premium cells may have a shorter life for the reasons raised by Mr. Calder and Ample Power.
2. I have the greatest respect for Nigel Calder, however I do not always agree with his conclusions in technical matters. Although I have and will continue to make mistakes, I have confidence in my judgement in the areas in which I write. There is always room for honest difference of opinion.
Honest difference of opinion does not include internal inconsistencies. It is unprofessional to compare an AGM on the basis of cycle life to a premium flooded cell on the one hand, while comparing its price characteristics to a cheap flooded cell on the other. For example, the link below illustrates the tested life-spans of deep cycle Trojan batteries "under lab conditions" by the manufacturer, the shortest of which is only 115 cycles (although there is no mention of test conditions)
See further remarks re: Mr. Calder below.
Equalization of flooded cell batteries is not hazardous, unless of course it is done without proper equipment or by persons not qualified to manage the process manually.
See section below on hazards of flooded cell batteries.
Nigel's opinion regarding the life of flooded cell batteries is simply that, "opinion".
The "opinions" in Mr. Calders Boatowners Manual are arguments based on facts. Instead of issuing a blank statement in an attempt to discredit Mr. Calders work, a well-thought out and documented response would have been due.
Perhaps Chuck Husick can illustrate how the two-bank vs. one-bank battery life example is scientifically deficient in Mr. Calders Boatowners Manual (p.26)? Could he then continue on to "Wiring for 12 Volts" which comes to the same conclusion (p. 121) with some additional points, such as Peukerts effect?
I am not aware of any authoritative works written by Chuck Husick (nor is amazon.com or barnesandnoble.com). Perhaps Chuck Husick knows something Mr. Calder does not. However, he offers no evidence to the contrary, only opinions.
What makes the works of Mr. Calder so compelling for so many people are the concise, clear, and consistent arguments he puts forth. This is one aspect of Mr. Calders writing that Chuck Husick may want to emulate, even if his opinions differ from Mr. Calder.
Misuse and abuse can destroy any battery.
A point we can all agree on. However, some batteries types are inherently more resistant to misuse/abuse than others. For example, users cannot contaminate the electrolyte chemistry of AGM batteries.
Again, it is up to the user to know enough and properly apply the knowledge needed to extract full value from a product. The use of high cost, lower performance batteries can be a good choice for some applications, especially when the user is unable or unwilling to properly manage the equipment.
As I will point out below, the costs of AGMs are not that much higher with respect to premium flooded cells while their performance is equivalent or superior. The references here are from windsun.com, Surrette, and Lifeline web sites. I've tried to stay in the 8D size range, when possible. As before, all cycle lives are assumed to be at 50% DOD. As costs go, I believe the life-cycle cost of a battery is the best indicator ($ cost/(Ah*cycle life))
|Lifeline AGM||Surrette 400||Surrette 500|
|Initial Cost ($/Ah)||$1.5||$1.11||$1.76|
|Life Cycles (cycles @ 50% DOD)||1,000||1,250||3,000|
|Volumetric storage (Ah/in^3)||0.111||0.113||0.081|
|Weight factor (lb/Ah)||0.61||0.74||0.81|
|Cycle cost ($/(Ah*cycle))||0.0015||0.00088||0.00059|
Ah/volume shows equivalency or superiority of AGM over Surrette 400 and 500 while AGMs also weigh less per Ah than their Surrette competition. Please also note that the Surrette 500 only comes in one non-standard form factor for marine applications.
If you associate no costs with the maintenance of premium flooded cell batteries, they can be 40-50% of the life cycle cost of a AGM. However, as I will show below, the maintenance costs of flooded cells are substantial. Let's assume that in order to calculate flooded cell maintenance costs you:
- Cycle once a day
- Pay yourself or someone "qualified" $20/hr for maintenance chores
- Each battery requires 1/4 hour maintenance each month
- Each cell (these are 8D+) requires 1/4 qt of $1/qt distilled water That equates to $0.000583/(Ah*cycle) (400) vs. $.00049/(Ah*cycle) (500)
Adding electrolyte maintenance costs to the initial purchase price results in
|Lifeline AGM||Surrette 400||Surrette 500|
|Adjusted Cycle Cost||0.0015||0.00147||0.00108|
Just the electrolyte maintenance makes flooded cells much less attractive on a life-cycle cost basis. 400 series Surrettes are price equivalent while 500 series are only 28% cheaper. Does a 28% premium make an AGM "high cost" with respect to a premium flooded cell which isn't available in any of the standard marine group sizes? (Consider installation)
Now consider all the other performance benefits of AGMs over flooded cells such as: sealed design, faster charge/discharge, lower self-discharge, higher charge efficiency, little/no gassing, vibration resistance, mounting freedom, etc. As far as performance is concerned, AGMs are superior in all respects to the premium cells listed here and they cost the same or 28% more once one accounts for maintenance costs.
The failure of users to properly manage equipment or systems is beyond my ability to correct.
(???) No comment.
3. I am very familiar with the use of AGM batteries in aircraft, having spent a large part of my career building and flying aircraft, including jet powered aircraft where wet Ni-Cad batteries were the standard fit. (I am a pilot / flight / instrument instructor and type rated in a number of high performance aircraft). The primary motive for use of the AGM battery was avoidance of the 100 hour deep cycle process required for wet Ni-Cads. The maintenance avoidance motive was particularly strong in military helicopters. As for safety, the AGM can also have problems when being recharged at a current flow of 450 amperes, which is more or less standard condition in many aircraft applications.
Chuck Husicks qualifications are impressive and but the anecdote is useless. Stating that AGMs cannot handle 450 Amps of charging current was apparently correct for his application. However, if a AGM bank is large enough, 450 Amps wouldn't even be a trickle charge. Thus, Mr. Husick needs to provide more information in order to make his experience relevant.
I derived my information from the manufacturer of Lifeline batteries. They indicate "no current charging limitations with voltage regulated charging". I assume this is correct, as they should know. Quality charging systems that are temperature compensated add another degree of over-charge protection.
With the exception of their immunity from accidental electrolyte spills they are NOT inherently safer than open cell flooded batteries. I urge you to consult the publications of major battery manufacturers of AGM batteries regarding necessary operational precautions. You may wish to consult the Specialty Battery division of Johnson Controls (414-967-6500) and ask for literature which covers this subject.
I have consulted the Lifeline web-site as well as the Dynasty literature. I suggest Chuck Husick does the same, as they disagree with his statements. AGMs are more vibration resistant, can operate in any orientation, and gas less than flooded cells, even under over-charging conditions. These attributes make AGMs inherently safer than flooded cells (beyond the obvious electrolyte spills).
For example, the Dynasty literature I received indicates:
The oxygen recombination feature of the DYNASTY VRLA battery and the resulting low emissions of hydrogen does allow for its use in industrial and commercial areas where the vented (wet) lead acid cells would not be acceptable.
The only caveat for the 99% recombination efficiency is proper charging. Dynasty apparently manufactures AGMs for use in UPS systems that cannot contaminate the computer centers they operate in.
Given that Johnson/Dynasty and Lifeline have the same "opinion" on the subject of AGM vs. flooded cell safety, I am not sure why Chuck Husick referred me to the Dynasty literature in the first place.
4. My comment regarding the 3:1 ratio between flooded and AGM batteries did not include premium quality flooded cell batteries. The price premium with those batteries is significantly less, as might be expected (ref your comments regarding ultimate life).
See my comments re: internal inconsistencies of price premium vs. life above. Chuck Husicks comparison is simply not valid. The only valid comparison is dollar cost per life cycle, accounting for maintenance costs.
5. I simply do not agree with your comments about the hazard of working with flooded cell batteries. I suggest you consult the Battery Council International regarding precautions in handling such batteries. Simple intelligent care is usually sufficient.
In his previous reply Chuck Husick stated:
"Perhaps I missed something in working with flooded cell batteries for more than 50 years, or perhaps my tolerance for toxicity is unusually high. I do not consider my various flooded cell batteries a toxic hazard."
Please review the following articles on the safety of lead acid batteries:
The industry and our government simply do not agree with Chuck Husick and your magazine should have caught that error prior to publication. All batteries are classified as toxic hazards. For example, all lead-acid batteries have to be reported under right-to-know clauses with the local authorities (ref: Dynasty MSDS).
In his current reply, Chuck Husick states that flooded cells require simple, intelligent care. In the handling of lead acid batteries, Dynasty advocates the use of proper gloves, eye protection, aprons, and boots to protect users from the electrolyte. This may fall under the "simple, intelligent care" category but NOT the non-"toxic hazards".
A visit to a location which services large numbers of such batteries will illustrate the real degree of risk. Perhaps a conversation with an insurance company which underwrites risk in such operations will enlighten you. Flooded cell batteries deserve respect, just as any other energy storage device.
I have been to such locations many times in my consulting work. H2 detectors, ventilation, emergency showers, etc. attest to the diligence that companies and OSHA attach to the charging process of batteries. A review of the above OSHA minimum requirements will help Chuck Husick further.
6. We are apparently doomed to disagree regarding the management of multiple battery banks. You will do it your way, connecting all in parallel. Your approach, and that suggested by Nigel will require less work on the users part. When things go well, all batteries age equally and no failures occur in any one battery the system is fine. In my experience it is not prudent to assume that things will always go well. Using my approach, I will become aware of a fault in a battery rather immediately. You will not. I will do it my way, using each in turn.
As the Dynasty literature, Ample Power, and Mr. Calder indicate, Chuck Husicks battery switching practice will lead to premature failure. Two scenarios that illustrate:
1) You switch all batteries in a bank individually and recharge the bank as a whole
There is no way to ensure that every battery in the bank has the same discharge level when one begins recharging them unless the user has a Ah meter that compensates for Peukerts effect then manually compensates for the self-discharge of disconnected batteries standing idle and their recovery. I would argue that no user can accurately ensure that all batteries reach the same discharge state prior to recharging.
As a result, some batteries will be overcharged, some will be undercharged as the uneven bank is worked towards float. See dynasty publication "Charging dynasty VRLA Batteries" which states "For optimum life, the rules are simple: Do not overcharge and do not undercharge". Flooded cell manufacturers advocate the same position because the fundamental chemistry is the same.
2) You individually charge and discharge batteries
While every battery will benefit from a proper recharge, the time it takes to recharge multiple batteries will allow sulphation to set in. While equalization can remove hardened sulfate compounds from the plates, the active areas invariably get attacked during this process.
Please see the following two references re: Peukerts effect and the merits of banks versus individual cells.
Chuck Husicks suggestion to use a $10 (precision?) hydrometer on a vented bank has much more merit. According to Surrette tech bulletin 509, a specific gravity reading deviance of more than .025 from the low to a high cell will point to a problem. There is no need to switch individual batteries from the bank - just test battery acid specific gravities. Testing while re-filling evaporated electrolyte should be sufficient, as long as the battery electrolyte is allowed to become homogeneous.
AGMs can be load tested from time to time, although similar batteries are unlikely to differ much in their performance. The chemistry of AGMs can be better controlled by the factory and cannot be contaminated by users refilling their cells.
If automation of the discharge / recharge process were a priority I could easily build a control system which would do all the required switching without supervision. You will do as you see fit.
Perhaps our differing ways will create a couple which will make the world spin faster.
I requested a professional reply. What is this statement is supposed to add to the discussion?
7. Obviously, I do not agree at all with your comments regarding the fact that "any boat" will appreciate the inherent "idiot-proofness" of parallel connection of all batteries. The aircraft I fly and in which I occasionally teach are designed to be flown by persons who are properly trained, not idiots. I believe that boats are not designed to be operated by idiots.
I could have phrased that better. However, everyone, including trained personnel makes mistakes and can temporarily behave like an idiot. Witness the QE2 hitting a rock ledge in MA because the skipper didn't account for the ship drawing more at speed. Limiting the extent to which "mistakes" can propagate through the system is a accepted design objective. For example, fuses should blow before wiring insulation melts/burns. The extent to which such failures are allowed to propagate are a function of the industry/market one operates in.
A large ship or aircraft is likely to feature multiple battery banks due to fuse / wiring / redundancy / distributed weight and other such considerations. However, the vast majority of boats would benefit from a large house bank and a starter bank for the engine(s). You may even want to install multiple starter banks if you have multiple engines that are supposed to be completely redundant.
Properly fused, even dead shorts will not cause the house bank batteries to fail (and yes, I assume that the short is not between terminals). Even a rare shorted cell within a bank will see less than equalization voltages as the Ample Power link above illustrates.
We do need simplicity and clarity in our systems designs, but not at the expense of ultimate reliability. I urge you to take a look at the electrical system in a modern business jet aircraft, an environment where unannounced or uncontained failure is not permitted. Perhaps application of those design principals to marine design will reduce the number of power failure situations which occur with some of today's designs.
Once again, I urge Chuck Husick to research the links I provided in this and my previous reply. Every link I provided points to higher availability and longer life of large banks versus several smaller banks within the context of a properly designed system. I am unsure what relevance his flight experience has, nor how much value the very complex, expensive requirements from the aviation industry would add to non-mission critical marine applications.
8. Your comment regarding the inability of a single deep cycle battery to support a massive load is correct. You will find that I have specifically stated that all available batteries should be paralleled when such loads are to be powered. I assume there may be emergency situations where the crew may be so overwhelmed by the workload that battery switching becomes an impossibly complex task. I have been fortunate in not encountering any to date. I doubt the wisdom of designing a system whose routine performance is compromised by a solution for a problem with may occur once in some number of years of sailing.
Extending Chuck Husicks argument to other aspects of sailing would point towards the uselessness of having EPIRBS, life-rafts and other such survival gear on board since it gets used so little, is expensive, heavy, and takes up many cubic feet of space.
Furthermore, as Mr. Calder, Ample Power, etc. point out, the routine performance of a large bank will always be greater than that of its constituent batteries alone, or that several smaller banks with the same combined Ah capacity as the large bank. Unless he can refute Peukerts equation, I kindly suggest that Chuck Husicks contrary opinion is wrong.
9. Your comments regarding the energy storage capacity of a battery bank are not unreasonable, except the suggestion that the capacity should be 4X the highest current load. That load is usually momentary. The total installed capacity is a matter for each user to determine, based on individual operating technique.
My suggestions were based on an industry consensus. Naturally, Chuck Husicks opinions may differ. However, I would appreciate fact-based responses that pointed to the contrary of industry consensus. Industry literature indicates that it is only the Gel and AGM battery types with their higher discharge capacity that allow banks to be sized smaller than the 4x current load rating recommended for deep-cycle flooded cells.
10. The battery recharge schedule in the article was illustrative. It was not intended to be a universal solution. It is up to the individual boat owner to determine a reasonable balance between energy demand and storage capacity.
Given that the battery and charging equipment industry offers simple, easy to use guidelines as to storage capacity, I don't think it would have been unreasonable for Chuck Husick to follow their lead and give the readers a reasonable example.
On long voyages I have often found it desirable to operate either the engine or a genset for some hours each day. The number of hours during which the battery bank is recharged must be a matter if individual judgement and will vary substantially with sailing conditions.
Indeed, a power-boat would find the use its of engines to be beneficial. However, sailing boats with auxiliary engines don't usually carry the fuel capacity to run the engine several hours per day on long passages w/o the use of auxiliary tanks. Sailing vessels have an inherent incentive to maximize fuel efficiency, electrical efficiency, and storage efficiency.
The lower self-discharge and higher charge acceptance make AGMs more attractive for sailors who want to maximize the efficiency of their charging systems. Particularly those who use renewable means for charging will see a benefit: Given the high cost of renewable energy charge systems, the lower charge requirements of AGMs can translate into significant savings or performance boosts.
Your desire to power a 20 ampere load for 24 hours before recharging the battery would indeed require a 1920 AH capacity bank. A total 20 hour rating stored energy capacity of 1850 AH can be achieved with the use of five Surrette model 12-CH-15PM 12 volt batteries. The total weight of the bank will be 1370 pounds. This bank will occupy more than 13 cubic feet. Unless you intend to use the batteries in place of normal ballast such a system may be impractical at the extreme.
I am aware of at least one monohull manufacturer that uses properly secured batteries in the bilges of their boats. I see several benefits: The weight is near the bottom, center of the boat, the batteries are protected by the keel, ambient temperatures will be low to ensure maximum battery life, more usable space elsewhere in the boat where it might be of more value to customers, and in the event of water entering the bilges, VRLA's can continue to operate. Ventilation requirements are minimal and can be easily incorporated. Lastly, batteries will not foul pumps the way cans and other foodstuffs will that some store in the bilges (see last issue of ON).
A boat with a constant 20A draw should be fairly large and easily carry the battery weight. If the boat is not large, the equipment that draws that much power is the source of worry, not the battery bank.
Further, unless the boat is in almost constant use the investment required will be difficult to recover.
This is a matter of target audience. I think a magazine titled "Ocean Navigator" denotes an audience that wants to spend some heavy duty time at sea or on board. Long periods of time on board translate into ample opportunity to recover the investments made. The articles in the magazine similarly point in that direction. Speaking of investments, how many people "recover" their boat investment? And how largely does a battery bank figure into the cost of a boat?
11. Using a series diode, even a Shottky diode in series with an engine starting battery is a poor idea. It would be far better to install a voltage sensing switch which will parallel the engine start battery with the others when charging voltage is sensed.
I never once advocated the use of a diode and this allegation proves that Chuck Husick did not research the links I provided and is blindly spouting opinion instead.
The isolator eliminator is a adjustable DC-DC power converter controlled by a charge regulator. Depending on the DC-DC power converter, conversion efficiencies can be 90%+ (I don't know what brand Ample-Power uses or if it is home-grown).
Adjustable DC-DC converters can step up as well as down. The isolator/eliminator allows the supply of a constant charging regimen to the starter battery regardless of the voltage swings typically encountered by the house bank on a boat. Even an equalization charge/voltage on the house side while charging a Gel/AGM starter battery can be easily tolerated.
Your suggestion that Nigel proof read my work is interesting. I read Nigel's writing at every opportunity and enjoy what I read. I do not always agree with him in every detail. I rather doubt that he will agree with all of my conclusions. If you are more content with Nigel's opinions, please, abide by them.
It is unprofessional by Chuck Husick to label other authors works "opinions" without delivering any proof that his views are more valid. Until he can do so, I suggest that Ocean Navigator hold off on publishing additional electrical opinions by Husick without peer review.
I have enjoyed communicating with you on this subject, however I believe that there is no purpose in further prolonging this exchange. I hope we have each benefited from this exchange of views. I wish you well in your sailing activities, including in your use of electrical systems on board your boat.
Chuck Husicks lack of willingness to prolong this exchange is troubling. Instead of providing fact-based information, every reply to date has no references that support his positions, little data, only opinions. These replies are supposed to be superior to the references I provided? Ocean Navigator should be able to do better than that.
Constantin von Wentzel