Thor Motor Coach CLASS B, Owner'S Manual

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E L E C T R I C A L S Y S T E M
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Battery Isolation Relay
When the motorhome's engine is running and the master
battery disconnect switch is ON, the vehicle's charging system
is connected to the auxiliary (coach) battery(ies) through the
Battery Isolation Relay. This connection provides charging
energy to the auxiliary battery(ies) when traveling.
When the motorhome’s engine is not running, the chassis
and auxiliary battery(ies) are electrically isolated by the use
of a battery isolation relay. This device prevents coach power
consumption from discharging the chassis battery while the
motorhome is parked.
ADDITIONAL CHARACTERISTICS OF THE
BATTERY ISOLATION RELAY:
1. The battery isolation relay electrically delays connecting
the auxiliary batteries to the vehicle charging system for
approximately 15 seconds; this allows the alternator time
to reach full charging ability.
2. After this initial time delay, the battery isolation relay
senses the voltage of the vehicle charging system. The
isolator connects the auxiliary battery to the vehicle’s
charging system only when the chassis charging system
reaches the correct voltage.
3. If the vehicle’s charging voltage drops below 13.2 volts
for a period of 4 seconds, due to low idle speed and/or
excessive load, the battery isolation relay will disconnect
the auxiliary batteries from the vehicle’s charging system
until the vehicle’s charging voltage returns to a level of
13.2 volts or above. For this feature, there is a built-in
delay period of approximately 10 seconds.
4. The battery isolation relay allows vehicle starting from
the auxiliary battery(ies) via the Emergency (Auxiliary)
Start Switch.
Emergency (Auxiliary) Start Switch
Your motorhome may be equipped with an Emergency (aux-
iliary or AUX) start switch. Located in the vehicle’s cockpit,
near the drivers seating area, this switch connects the coach
battery(ies) to the vehicle’s starting circuit to provide addi-
tional starting power.
This feature is used for situations when the chassis battery is
too depleted to start the vehicle on its own. Connecting the
coach battery(ies) to the engine starting circuit may provide
the needed energy to start the motorhome’s engine. When the
Emergency Start Switch is released, the coach battery(ies) are
disconnected from the engine starting circuit.
This feature is available on ProMaster-based Class B motor homes
with either standard AGM batteries or the optional Li-ion battery
power system.
TO OPERATE:
1. Ensure the master battery switch is ON.
2. Depress and HOLD the ‘EMER START’ switch, located
on the front driver’s dash.
3. Use the ignition switch (key or start button) to start
chassis engine.
4. Release the ‘EMER START’ switch after the engine has
started.
NOTE: When using the Emergency Start feature, do
not hold the ignition key in the start position for more
than 30 seconds.
OTHER EMERGENCY STARTING TIPS: If your
vehicle battery is too depleted to start the engine,
and the coach battery(ies) is also too depleted, try
operating the generator for a short period. This might
provide enough charging energy to allow the vehicle
to be started via the Emergency Start feature.
NOTE: The Emergency Start feature is not available
on Sprinter-based Class B motorhomes.
Turn off all 12 volt DC devices before using the
emergency start feature. This will help ensure that all
available energy stored in the coach battery(ies) can be
used for vehicle starting.
NOTICE NOTICE
Unless you intend to run the vehicle engine, keep the
ignition switch in the OFF position. Doing so will:
• Reduce the risk of unnecessary chassis battery
drain.
• Allows the battery isolation relay to connect the
auxiliary battery to the coach charging system.
CAUTION CAUTION