Which Batteries? IT ALL DEPENDS

http://gilwellbear.wordpress.com/2013/01/13/which-batteries-are-best/

Which Batteries are Best?

Which batteries are best is a little bit of a “religious” discussion, like which anchor is best or what’s the best micron size of fuel filters; To some extent, the best answer is, “it depends” on how you plan to use them.

First, I’d suggest avoiding all 8D form factor batteries, not because they’re inherently bad, but because they’re very heavy.  At 160# or so per battery, more for some, I can not handle 8Ds by myself.   When they fail – and they do fail – you need to be able to handle them yourself, because it won’t happen when you’re at your home slip with lots of help available!  Two 6-volt GC-2 Electric Car batteries will easily fit in the same foot print as a single 8D, and will have very nearly the same capacity (measured in Amp Hours).  Three GC-2 batteries will just fit in some 8D battery boxes, so that would allow six GC-2s in the same space as two 8Ds.  If so, that will give you significant additional capacity in the same space two 8Ds require.  For example, most 8D batteries range around 225 aHr; a pair of GC-2 batteries in series will give 12V and range around 215 aHr.

The technology choices for deep cycle marine/commercial batteries boils down to the selection of “flooded,” “AGM” or “Gel” batteries.  All three are traditional lead acid technology.  Optima batteries are a special – and expensive – case of lead acid technology.  Each of these technologies has pros and cons associated with them.  Some of the pros and cons will carry personal value for some, but not for others.

Flooded lead acid batteries require regular maintenance.  That means periodically checking and adding distilled water, and periodically equalizing them.  Flooded lead acid Electric Car batteries are available everywhere in the world; even in the third world.  AGM and Gel batteries may not be either available or affordable in many places, even in the US.  AGM and Gel technologies are maintenance free.  You can’t add electrolyte, and they generally can’t be equalized. (Some AGMs can, but that is manufacturer-specific, and the general rule is, no.)  AGM and Gel can be mounted in any position orientation.  AGM and Gel batteries are more affected by ambient heat, and Gel more than AGM, so mounting them in the engine room can be a problem in some installations.  Charging deep cycle lead acid batteries should be done with a modern 3-stage charger using the correct charging program for the technology.  There are lots of technical issues around battery charging which I’m not discussing here.  Suffice it to say that a 2K charger (100A DC output) with a 675 aHr battery bank is a perfectly acceptable solution; not perfect, but plenty acceptable from a lifetime ROI perspective.  Flooded lead acid batteries are the least expensive to buy (lowest capital cost).   The commodity cost of lead has driven battery cost way up in the last few years, and with the Chinese buying the entire world-wide supply, that commodity cost will probably continue to rise.  My summer, 2012, buying experience was that I bought six 6V EGC-2 batteries rated at 230 aHr in June/July, 2012, for $92 apiece, from Sam’s Club.  At that time, a single AGM 8D was $600.  So I bought 690 aHr from Sam’s Club for what I would have paid for one 245 aHr AGM battery at Hamilton Marine.

Now, here following is the “religious” part of the battery topic.  The real issue is, what’s the best ROI on the battery technology selection you buy?  And the answer is, again, “it depends.”  From the reading I’ve done and the experience I’ve had aboard Sanctuary since 2004, running 40K miles and 4500 hours engine hours, and anchoring out 2/3rds of the time,  I am persuaded that if you are a cruiser -  if you actually use your boat, put many hundreds of hours on it each year, and anchor out in preference to using marinas – flooded wet cells provide the best ROI.  They are the least expensive to buy, and return good charge/discharge cycle life.  The Sam’s Club batteries with Duracell branding are manufactured by East Penn, so they are made-in-the-USA and are the same batteries that you’d buy retail, for more money, over the counter at NAPA or West Marine.  Yes; literally the same batteries, made by the same people on the same production line in Pennsylvania.

My own personal experience with AGM batteries (Deka, also made by East Penn) did not meet my desires or expectations.  I have had two sets of AGM batteries fail after only 3 – 4 years in service (less than 300 charge/discharge cycles).  They were not excessively discharged in service.  They were charged with the correct charging programs on both my Magnum inverter/charger and the Balmar engine alternator. And when they failed, they failed overnight, not slowly with some advance warning. They did not return the cycle life they should have been able to return, and at now $600 apiece, I no longer feel they’re the best choice for ROI.  For people who don’t use their boats much, those who use marinas rather than anchor out, etc., the AGM and Gel maintenance free batteries may be a good choice.  These owners will get several years of service from the batteries without realizing that they haven’t returned their rated cycle life.  FINALLY, AVOID THE DISCUSSION OF HOW MANY YEARS PEOPLE GET FROM THEIR BATTERIES.  THAT DOES NOT TELL YOU ANYTHING ABOUT THE NUMBER OF CHARGE/DISCHARGE CYCLES THE BATTERIES ACTUALLY RETURNED.

Optima batteries are an AGM technology called “TPPL;” thin plate pure lead.  They return lots of aHrs per unit of space, and are efficient to charge.  They are expensive to purchase, per aHr.  The technology has great potential, but not for me at current consumer price levels.  LiON batteries are an entirely new technology, requiring different charging equipment.  Converting to an LiON system is out of the question today, from an ROI perspective.

One final “religious” argument comes up with comparing Sam’s Club batteries to Trojans, Surette, Rolls, or other high end flooded wet cell brands.  Again, “it depends.”  In my opinion, for coastal cruising in the US, the Bahamas and Canada, Sam’s Club batteries are fine.  If you’re a blue water cruiser who’s going to circumnavigate and be in places like Figi, or south of 60 degrees south in Channel Islands or Straights or Magellan in Chili, well, maybe not there.  Maybe not the southern and western Caribbean.  But most single engine trawler owners are not going to circumnavigate – or cross the Atlantic – so Sam’s Club batteries are fine.

BOTTOM LINE

1) WHAT IS THE SERVICE? STARTING? DEEP CYCLE? SOLAR STORAGE? SERVICE LIFE? One battery does not fit all uses or requirements. Consider a starting battery bank, a electronics isolated battery bank and a "hotel" or "house" battery bank.  (Hint: Interconnect battery switches could be used for combining in special circumstances. BUT NEVER INTERCONNECT THE STARTING BATTERY OR BANK - RATHER, CARRY A SET OF QUALITY BATTERY JUMPER CABLES.)

2) CONSIDER THE "BANG FOR THE BUCK" ANALYSIS - what technology provides the lowest cost storage of energy "Amp-Hours" for a dollar? (Hint: wet lead-acid cells) BUT you must also calculate the number of discharge cycles for a true analysis.

3) REMEMBER THERE IS ALWAYS A "COST" FOR USING NEW "HIGH TECHNOLOGY" such as requiring a new charger with a specific charging cell voltage, a new battery box size and new battery interconnect cables etc.

4) LOOK HERE FOR MORE OF THE BATTERY STORY... New vs Old
Lithium Iron Phosphate - LiFePO4 - 5x more discharge cycles than lead-acid with up to 70% depth of discharge without memory or damage with half the size/weight of wet lead-acid batteries.
http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

Nickel Iron - NiFe - Edison Cells - near indestructible but large size - up to 50 year lifetime - change Potassium Hydroxide (KOH) or Sodium Hydroxide (NaOH) low cost electrolyte about every 5-7 years to renew battery
http://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery

5) SERVICE IN TIMBUCTO - Will anyone be able to help you when you need a new battery or service?