Cruising World – August 2019

august/september 2019

cruisingworld.com

78

HANDS-ON SAILOR

not necessarily conform to

traditional Battery Council

International group sizes.

Understand that the internal

components for these batteries

are compressed to maximize

the amount of plate contact

area with the glass-mat medi-

um before being dropped into

the outer case. The advantage

here is that these batteries will

typically have higher current

densities, meaning more power

for a given physical dimension;

the disadvantage, however,

might be the way that space

for batteries was engineered

into your boat. You might fi nd

that the battery storage area is

going to need extensive mod-

ifi cation to fi t your new-age

powerhouses. That’s another

factor that could skew the cost-

per-amp-hour calculation.

The advantages to both

AGM and gel-cell batteries

include their mechanical prow-

ess. The pressing together and

inherent rigidity of the gel in

the gel-cell case creates batter-

ies that can withstand vibration

and rough-sea pounding much

better than their fl ooded-cell

counterparts. Mechanical

failure of batteries is not that

uncommon.

READY FOR LITHIUM?

Over the past decade, the

buzz in the world of batteries

has centered on lithium

technology. Here we have all

the advantages of AGM tech-

nology, plus an opportunity to

have even more current density

coupled with an exponential

reduction in weight.

What’s not to love?

Well, unless you’ve been

living under a rock, you’ve

also heard about boats using

lithium batteries that have

burned to the waterline.

There are a lot of factors to

understand here, which is

why you need to think about a

battery installation in a system

context, and also consider the

technology itself.

At least some of the fi res

caused by lithium batteries

were due to the actual chem-

istry used. But there have also

been issues with how they were

manufactured (cleanliness

when making the individual

cells is imperative) and with the

design—or lack of it—when it

comes to battery management

systems, or BMS as they’re

called in the trade.

Today, virtually all the ven-

dors I’m familiar with are using

lithium-iron-phosphate or

lithium-nickel-manganese-co-

balt-oxide chemistries, both of

which have good track records.

It’s important to understand

that if a lithium battery does

catch fi re, conventional

fi re-extinguishing systems will

not put out the blaze. Once the

electrolyte catches fi re (regard-

less of actual chemistry, all of

the electrolytes are fl ammable),

the only way to extinguish it

is to cool it with water—lots

of water! That said, the

reputable manufacturers seem

to have fi gured out all of this

and do absolutely everything

possible to ensure that a fi re is

extremely unlikely.

To keep things in context,

consider this: Liquefi ed

petroleum gas is extremely

fl ammable and explosive, yet

we use it aboard cruising boats

quite regularly. If recognized

standards for installation and

maintenance are followed, any

inherent danger is minimized

to the point where we hardly

give it a thought. The same

thing needs to happen with

lithium-battery technology.

The American Boat and

Yacht Council is working

on developing a technical

information report covering

lithium-battery installations,

and it is in draft form and

being reviewed as I write

this. Hopefully we can get a

published document in place

in 2020.

But I digress—back to the

systems approach, which I

can’t emphasize enough. If

you are the technical type and

determined to have the latest

and greatest technology on

your cruising boat, be prepared

to spend some real money on

all the elements required for

the system to operate safely.

First, you will have trouble

with your engine alternator

running too hot as it works

hard to keep up with the

charging needs of these batter-

ies. It makes sense to install a

thermal sensor that shuts down

the alternator if it gets too hot.

Balmar offers this option with

its alternator/ programmable-

voltage-regulator combination.

Next, make sure your

shore-powered battery charger

has appropriate settings for

lithium batteries. Then provide

as much cooling as possible to

the alternator; I’ve seen electric

blower fans employed for this

purpose.

Then, be sure you under-

stand how the BMS on your

boat functions. You might

discover that the BMS is

engineered to electrically shut

down the battery/batteries if it

senses a problem. Well, if the

engine is running, this sudden

shutdown could cause a voltage

spike in your DC-electrical

system, possibly damaging

expensive and mission-critical

electronics. Yanmar recom-

mends installing a conventional

battery as a system backup in

case this happens. That’s yet

another expense and one more

thing to worry about.

On the plus side with either

lithium or AGM technology,

with careful planning and load

analysis, the recharge absorp-

tion rate is so high that you

might just be able to eliminate

that AC generator to recharge

batteries when offshore. Add

some solar- and wind- generated

power, and engine run time

with the alternator can be

reduced dramatically.

BOTTOM LINE

ON BATTERIES

I’m of the opinion that we are

at an interim phase in tech-

nological development when

it comes to batteries and the

systems that surround them.

We are seeing cities around

the world that are mandating

no fossil-fueled vehicles within

city limits. Initiatives like this

will force the play toward more

and more electric vehicles.

With that comes engineering

investment that will pay off in

the form of better batteries,

enhanced safety protocols and

trickle-down technology useful

to the marine sector.

For now, though, I’m

going to follow the suggested

directive from the West

Marine buyers’ group and

go with AGM technology.

An AGM TPPL battery is

mechanically rugged, requires

minimal maintenance, will

probably work with my existing

battery charger and alternator

combination. Better yet, they

can be heavily discharged and

and recharged quite rapidly.

That’s good enough for me.

Ed Sherman is vice president

of education at the American

Boat and Yacht Council, and

is a frequent CW contributor

on technical issues, as well as a

longtime Boat of the Year judge.

Because AGM batteries do not always conform to standard

battery sizes, replacing a traditional battery bank (above)

may require extensive remodeling.

ED SHERMAN