Electrical System; Introduction; Batteries; The Required Battery Capacity - Vetus DIESEL EP2200K Instructions D'installation

9 Electrical System

9.1 Introduction

The electric motor is suitable for 24 Volts only.
The electrical system has an insulated return..
The electric wiring between the motor and the regulator is
already fitted.

9.2 Batteries

The common starter battery is not suitable for an electric propul-
sion installation.
Instead, semi traction or traction batteries should be used.
The characteristics of these types of battery are:
Starter battery - fitted with a large number of very thin plates -
especially suitable for providing a high current for a very short
period.
This type of battery is not suitable for being discharged regular-
ly by more than 35% before being recharged, otherwise its use-
ful life(*) becomes considerably reduced.
Semi traction (Deep-cycle) battery - this type of battery is fit-
ted with fewer, but thicker plates than a starter battery - and is
suitable for providing a fairly large current (but not as large as a
starter battery) for a longer time.
Also, this type of battery can be discharged by 80% before
needing to be recharged, while maintaining a reasonable useful
life(*).
Traction battery - this type of battery has tubular plates - and,
like the semi-traction battery, will provide a fairly large current
for a longer time.
However, its useful life (*) when discharged regularly by 80% is
considerably longer than for a semi-traction battery, so it is often
used where the battery is discharged by 80% on a daily basis,
in fork-lift trucks, for example (cyclic operation).
Batteries
4 x 12 V - 230 Ah (K20) - in series/parallel
6 x 12 V - 230 Ah (K20) - in series/parallel
8 x 12 V - 230 Ah (K20) - in series/parallel
Electric Propulsion EP2200K, EP2200KH
(*)Useful life here means the number of charge-discharge
cycles that a
permanently reduced to 80%.
With an 80% discharge, the useful life of a semi-traction bat-
tery is 300 to 400 charge-discharge cycles, while for a trac-
tion battery this is 1500 to 2000 charge-discharge cycles.
Although traction batteries perform better than deep-cycle bat-
teries, they can only be recommended for very intensive use
(hire boats, for example) due to the much higher purchase
price.

9.3 The required battery capacity

Two factors play an important role in determining the battery
capacity:
- The required range (= cruising time x speed)
- The expected average current consumption.
The range is not only dependent on current consumption, but
also the speed of the vessel. The maximum current consump-
tion of the electric motor is about 120 Amps. However, if you
travel at a speed that is 20% below the maximum, current con-
sumption will be less than half this (about 50 Amps).
The available capacity of a battery is dependent on the size of
the discharge current.
Vetus can supply semi traction batteries for electrical propulsion
with a capacity of 230 Ah at a 20 hour discharge.
However, the available capacity of this battery is only 180 Ah
over a 5 hour discharge.
Use the Table below to determine the required battery capacity.
In order to give an idea of the possible range, this is based on
a vessel which at maximum motor power (thus maximum cur-
rent) can reach a speed of 4.9 knots (9 kph). Such a vessel
would have a current consumption of just 50 Amps when the
speed is reduced to about 80% of the maximum (3.9 knots,
7.2 kph).
Battery selection table
Battery capacity Sailing time / Range
at 24 V and at a current of 120 Amps
20-hour discharge and a speed of 4. kn (9 kph)
460 Ah (K20) 2 hour 45 min. / 13.5 nM (25 km)
690 Ah (K20) 4 hour 30 min. / 22 nM (40 km) 12 hour 45 min. / 50 nM (92 km)
920 Ah (K20) 6 hour 30 min. / 32 nM (58 km) 17 hour 45 min. / 69 nM (128 km)
battery can undergo before its capacity is
Sailing time / Range
at a current of 50 A and
a speed of 3.9 kn (7,2 kph)
8 hour / 31 nM (58 km)
ENGLISH
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