Battery Cables - Beta Marine Beta 14 Installation Manual

BATTERY CABLES

1. Starter batteries should be as close to the engine as
practically possible. The reason for this is to ensure
that the maximum voltage from the battery is available
to the starter motor. The longer the cable run - the
more will be the voltage drop. This is due to the
resistance of the cables.
2. Generally speaking for smaller engines (say under
60hp) we recommend battery cables of 25mm2
conductor cross sectional area with length up to 1.5m
per cable. That equals a cable run of 3m total which
would have a voltage drop in the region of 0.8v if the
starter motor was using 160 amps when motoring.
Battery cables that are too small will overheat and
their insulation could catch fire.
3. When the supply is switched on to the starter motor
there will be a massive inrush of power in the region
of 5 times the motoring current. The battery will
be expected to supply this inrush and then recover
sufficiently to give the motoring or 'rolling' current.
2
25mm Cable
Engine Cranking Amps
Up to Beta 38
Up to Beta 50
Up to Beta 60
Up to Beta 105
Beta 150
2
35mm Cable
Engine Cranking Amps
Up to Beta 38
Up to Beta 50
Up to Beta 60
Up to Beta 105
Beta 150
Cable Volt drop*
100
120
170
210 / 250
333
Cable Volt drop*
100
120
170
210 / 250
333
If the correct battery is selected but the engine will
not crank at sufficient speed after the inrush then
(assuming battery cables are the correct size) the
battery is either discharged or faulty.
4. If the voltage at the starter motor terminals after the
inrush is not at least 10.5 volts it is likely that the
motor will either crawl at insufficient speed or not turn
at all. Battery cables could overheat.
5. Battery cables are sized on the motoring or rolling
current of the starter motor and the length of battery
cable run. This length is the total distance of both the
positive and negative cables added together. Under
normal circumstances the voltage drop in the starter
battery cable circuit should not exceed 0.8 volt and in
any circuit should not exceed 1.2 volts.
6. Please note that cranking time should be no longer
than 10 seconds, with at least a 10 second rest
between attempts.
Max length, both cables added together
0.0017V
0.0017V
0.0017V
0.0017V
0.0017V
Max length, both cables added together
0.0013V
0.0013V
0.0013V
0.0013V
0.0013V
20
4.7m
3.9m
2.8m
Not suitable
Not suitable
6.2m
5.2m
3.6m
2.5m
1.8m (70mm cable preferred)
2