All About Lead-Acid Marine Batteries

Killing Your Batteries Quickly. The "Don't do This" List.  Generally people are interested in how to prolong the life of their batteries.  Much of the answer is to avoid several practices that kill batteries quickly.  If you are new to boating, this is where you should start.  1) Ignore the battery.  Do not monitor the electrolyte level if you have a "wet" battery.  If you do not know what you have, you should assume it is the "wet" variety until proven otherwise.  The battery will completely dry out in anything from 6 months to 3 years ands you will be shocked, shocked to learn you have no power at the start of your annual vacation.  Also shocked to learn that batteries require a small amount of preventative maintenance.  (full article)

Maintaining Lead-Acid Batteries.  This is the "Do list" which describes how to avoid all the problems listed in the first section.  All boat batteries are lead-acid, which describes the chemistry involved in the battery.  Some are described as wet cells, some as "Maintenance free" others AGM or Gel cells.  Some are starting batteries, others deep cycle and some dual purpose, which means not optimal for anything, but they have their place.  They are all lead-acid batteries and differ in slightly, the newer ones differ in ways to make them non-spillable or easier to maintain.  1) Use an appropriate battery charger.  Having the wrong charger is probably the best all-around, least obvious way to damage batteries.  (see full article)

How do Lead Acid Batteries Work?  There are so many sites devoted to lead acid batteries, if I wrote one more explanation I'd just be rehashing what others have said well enough.  Basically, lead acid batteries all use a chemical reaction to produce electricity.  This reaction moves sulfate from the sulfuric acid containing electrolyte to the plates.  Fully discharged, the electrolyte is plain old water.  The reaction is mostly reversible, so pumping electricity back into the battery moves the sulfate back into the electrolyte, increasing the concentration of sulfuric acid. The most common battery failure mode, sulfation, is getting the sulfate locked up in the plates so the battery will not fully recharge.  Sulfation is easy, just leave your batteries discharged for a few days.  (full article with links)

How many batteries do I need?   How do you use your boat?  The ABYC electrical standards have tables and formulae for determining how large a battery bank to install on a boat given the likely loads and the amount of time they are on each day.  I have put these principles into spreadsheets incorporating Peukert's Equation and have not found the standards to be particularly helpful.  What jumps out every time I run the numbers is that most of the battery capacity is consumed by the relatively small loads that run hour after hour, like refrigeration.  Less commonly considered, and pretty much ignored by the standards, you need a large battery bank to drive a large inverter. If your batteries are too small you will not be able to supply the current your large inverter needs to run the toaster, particularly after the batteries become partially discharged.  (full article)

How Long Should I Expect My Batteries to Last?  Not as long as you would like.  All lead acid batteries age and fail no matter how well you take care of them.  By following best practices you can maximize the life of your batteries.  This means avoiding all the things that kill batteries quickly.  If you get five years out of a set of batteries you are doing very well.  Seven to ten years - exceptional, you are doing everything right.  As a cruiser, cycling your batteries every day, you may be pressed to get a year or two out of batteries.  (full article)

Battery Charging.  Poor charging practices will kill batteries fairly quickly.  Leaving them discharged for much time at all "sulfates" them, temporarily or permanently reducing battery capacity.  Overcharging them drives off water and dries them out, permanently damaging the batteries.  There are also slow killers  Leaving them on charge continuously oxidizes the positive plates, which eventually fall apart.  Deeply discharging your batteries physically causes the plates to crumble sooner rather than later.  Then there is the matter of getting batteries charged as quickly as possible without damaging them.  If you get back to the dock every few days this is not a big problem -- use a modern marine two or three stage electronic charger.  If you live on your batteries every day like a cruiser, then everything becomes more challenging.  (full article)

The Less Electricity You Use, the Easier Your Battery Issues Become.  Unfortunately, this is bucking most of the trends.  

LED running lights are a joke, energy-wise in the big picture, just my opinion.  Eating by LED or candlelight may be romantic, but in the galley I think it's dangerous.  I boat year-round; I like lots of light and I have it.

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