Professional BoatBuilder - December-January 2018

DECEMBER/JANUARY 2018 39

THE WORLD’S FIRST

MONOBLOCK

COMMON RAIL

RATED-POWER: 59 - 130 kW

TORQUE:up to 360 Nm @ 2400 rpm

DRY WEIGHT:

STEYR MOTORS North America, Inc

2310 S. Hwy 77 Ste. 110#338 | Lynn Haven, FL 32444 | USA

http://www.steyr-motors.com|1-850-784-7933

up to 360 Nm @ 2400 rpm

DRY WEIGHT: 240 kg

Surprisingly, perhaps the biggest

impact on what will come to predom-

inate in the marine world—LFP, NMC,

or some other chemistry—may be the

fallout from the Volkswagen “diesel-

gate” scandal.  is has caused a major

rethink in Europe regarding diesel

cars in general. Whereas tax structures

have for decades favored diesels, with

protective measures, etc. Given the

correct BMS and packaging, it is argu-

able that NMC can be made as safe as

LFP; certainly some NMC batteries

are safer than some LFP batteries.

Ultimately, regardless of chemistry, for

the consumer the only real protection

is to buy from a recognized marine

vendor with an excellent track record.

through the boat can blow out sensi-

tive electronics—in other words, the

battery protects itself at the expense of

the boat.

A recent Yanmar Technical Bulletin

(June 2017) addresses this issue as fol-

lows: “Always keep a lead-acid battery

in the system directly connected to the

alternator.  is to supply the engine

ECU [engine control unit] and starter

motor and prevent spikes in the sys-

tem when the BMS stops the charging

of the li-ion battery.”

 ere are other issues with di ering

charging regimens and charging volt-

ages for lithium-ion batteries as com-

pared to lead-acid. And it is not just a

matter of regimens and voltages. As

we will see below, the high charge

acceptance rate of lithium-ion batter-

ies will stress charging devices and the

boat’s wiring in ways they have never

been stressed before. A boatyard or

marine technician confronted with a

customer who wants to replace exist-

ing lead-acid batteries with lithium-

ion would be well advised to insist on

a full analysis of the boat’s energy sys-

tems prior to undertaking any work.

(See “Chemical Conversion,” by Mark

Lenci, Professional BoatBuilder No.

155, for an account of switching from

lead-acid to lithium-ion batteries on a

cruising sailboat.)

Chemistry Choices

Two chemistries predominate in the

marine lithium-ion world: lithium-ion

iron phosphate (LFP), and nickel

manganese cobalt (NMC). If LFP is

driven into thermal runaway, it will

not generate high enough tempera-

tures to set itself on  re, whereas NMC

can. For this reason, LFP has o en

been described as intrinsically safe

and has been promoted as the only

suitable chemistry for marine applica-

tions. As noted above, the electrolyte is

still  ammable, and there have been

some notable  res and boat losses (as

well as LFP hoverboards that have

caught  re).

Within the LFP and NMC families

are literally dozens of variations in

construction, chemical doping, See us at • Booth 2

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