Know How: Batteries - Sail Magazine

Know How: Batteries

Author:
Publish date:

Given the ongoing proliferation of electronic equipment and gadgets like watermakers, autopilots and electric winches on modern sailboats, it’s little surprise that batteries have become increasingly important. Typically speaking, marine batteries are 6- or 12-volts and are used as cranking batteries to start an engine, as deep-cycle batteries for house loads or as dual-purpose cells.

optima-bluetop31_top

Cranking batteries are typically lead-acid and have many thin lead plates to expose maximum surface area and produce maximum power in short bursts in order to start a boat’s auxiliary engine. These batteries are recharged via an alternator once the engine is running.

Unlike cranking batteries, deep-cycle batteries are designed to service smaller loads over a much longer period. These “house batteries” are built using a variety of technologies. The most common lead-acid batteries are wet cell (or flooded), gel cell and absorbed glass mat (AGM).

State-of-the-art lithium-ion batteries can also be used to handle large capacities and are capable of withstanding many deep-discharge cycles. House batteries typically have fewer (but much thicker) lead plates than starting batteries and are available in capacities of 25AH (amp hours) and 225AH. They are also often wired together to create a bank of batteries with much greater capacities. Look for batteries that meet your anticipated power needs and offer the most charge cycles at 50 percent discharge. Also, be sure that your entire house bank is comprised of a single battery type—never mix battery types (or old and new batteries), as they will have different charge and discharge rates.

Dual-purpose batteries used to start an engine and service house loads are targeted toward small boats that only have space/weight accommodation for a single battery. These provide a reasonable amount of starting power and cycling capacity relative to their size, however, they are typically not suitable for extended cruises. 

Photos courtesy of (from left) Optima, Mastervolt, West Marine

Related

01b_WALKING-KEDGE-OUT-cmykpromo

Getting More Use From Kedge Anchors

If you are cruising, you need at least two anchors on board for the simple reason that you must have a backup. Imagine having to slip your anchor on a stormy night with other boats dragging down on yours, or having your rope rode severed by some unseen underwater obstacle, ...read more

SailAwayCharter

How-to: Navigating on a Bareboat Charter

So you graduated from navigation class where you practiced dead reckoning, doubling the angle on the bow and maybe even celestial nav, and you now feel well prepared for your first charter trip. Well, you won’t be doing any of that on vacation—not past the first day, anyway.Most ...read more

04-Turtle-rescue

Turtle Rescue in the Vic-Maui

Strange and often wonderful things can happen in the course of an offshore sailboat race, and one of the strangest and most wonderful things we’ve heard of recently took place during the 2,300-mile 2018 Vic-Maui race, from Victoria, British Columbia, to Lahaina, Hawaii.It ...read more

dorcap-open-blue

ATN Inc: Dorcap

COOL SLEEPYou’re fast asleep in a snug anchorage, forehatch open to catch the breeze, when you’re rudely awakened by a sneaky rain squall. Now you’re not only awake and wet, you’re sweltering with the hatch closed. Sucks, right? That’s why ATN came up with the Dorcap, an ...read more

HIGH-RES-29312-Tahiti-GSP

Ask Sail: Who has the right-of-way

WHO HAS RIGHT-OF-WAY?Q: I sail in Narragansett Bay, which is a relatively narrow body of water that has upwind boats generally going south and downwind boats generally going north. When sailboats are racing, the starboard tack boat has the right-of-way over the port tack boat, so ...read more

albinheaters

Albin Pump Marine: Marine Water Heaters

IN HOT WATERSweden’s Albin Pump Marine has introduced its line of marine water heaters to the United States. Complete with 130V or 230V AC electric elements, the heaters can be plumbed into the engine cooling system. They feature ceramic-lined cylindrical tanks in 5, 8, 12 and ...read more

03-squalls4

Squall Strategies

Our first encounter with a big squall was sailing from San Diego to Ensenada, Mexico. We left at 0200 to ensure we’d get into Ensenada before our 1300 haulout time. The National Weather Service had forecast consistent 15-20 knot winds from the northwest, which was perfect for the ...read more