Professional BoatBuilder - December-January 2018

DECEMBER/JANUARY 2018 43

PROVEN MARINE TECHNOLOGY

http://www.yanmarmarine.com

CLEAN INTERCONNECTIVE QUIET POWERFUL FUEL EFFICIENT

OUR NEWEST, MOST VERSATILE,

COMMON RAIL DIESEL ENGINE > 4LV Series

150-170-195-230-250 MHP

CLEANER,

QUIETER,

and produces more and produces more

TORQUETORQUETORQUE & &

ACCELERATIONACCELERATION

than any other

engine in its class.

For one of our experiments we had

a massive lead-acid battery bank capa-

ble of absorbing for hours on end any

charging energy I could throw at it. We

were operating in Europe, where the

standard shore-power outlet is rated

for 230V and 16 amps, which equates

to 3.6 kW (pretty much the same as a

U.S. 120V, 30-amp shore-side supply).

coil has an e ect similar to bundling,

and if the coil is also in sunshine, we

have an additional heat source.  e

combination e ectively derates the

cable. We can’t do much about this

other than to avoid coiling the cord in

direct sunlight and to not push the

cord too hard.  e end  ttings then

become the weak link.

high levels of current  ow, you have a

signi cant  re risk.

Given the scarcity of cables with a

temperature rating above 221°F, there

is no good antidote to this situation

other than to choose alternator cables

as large as is practicable, to mount

them in free air to maximize cooling,

and to ensure that the positive cable is

not run in contact with, or adjacent to,

any grounded surface.  is is less of a

concern once a cable runs well clear of

the alternator, which provides the

opportunity for some of the heat in it

to dissipate.

Output cables from charging

devices will be running at high loads

for extended periods of time. Installers

and repairers should keep in mind that

ABYC and ISO (International Organi-

zation for Standardization) ampacity

tables, typically used for determining

the maximum current-carrying capa-

bility, or ampacity, of cables, are not

particularly conservative and as such

are more suited for intermittent loads.

Once again, it is advisable to err on the

conservative side and use larger-than-

mandated cable sizes.

In conventional installations, charg-

ing cables frequently end up in a bun-

dle with other cables, in which case, as

the cables heat up, the heat is trans-

ferred to the other cables in the bun-

dle, reducing their ampacity. In the

past, the ABYC has included derating

factors for AC cables in bundles, but

has not done this for DC. As of the last

revision of the electrical standard

E-11, these derating factors have also

been partially applied to DC cabling.

 is may require another upsizing of

the charging cables. Note also that the

same derating factors, and upsizing,

need to be applied to all the other

cables in the bundle, especially those

likely to see continuous loads at, or

close to, their rated ampacity.

Shore-Power Meltdown

 e shore-power cord and its end

 ttings are another weak link in our

high-charge-rate systems. Excess

lengths of shore-power cord are fre-

quently coiled up on the dockside. A

Batteries170-ADFinal.indd 43 10/31/17 12:19 PM