Power recovery through intelligent energy management is the focus of the new system Prevost calls PRIME. Unveiled during the UMA EXPO 2013 in Orlando, FL, the company says PRIME marks a milestone in the electrification of its coaches.
The system uses braking, deceleration and negative torque situations
to create a low-power regenerative system. Using engine downtime to
charge the batteries and compress air reduces fuel consumption. PRIME
introduces new logic for controlling and energizing the alternators and
air dryer when the engine is under minimal load. Prevost has also added a
new equalizer to monitor the state of charge (SOC) of the batteries.
The company says this intelligent management of energy maximizes battery
life based on its inherent characteristics.
Prevost will offer PRIME as an option on the upcoming 2014 model
H-Series and X-Series seated coaches and make it a standard feature on
2014 model H3-45 VIP and X3-45 VIP conversion coaches.
“We choose an easily obtainable AGM battery with a 800CCA, 100Ah
specification with 190 minutes reserve capacity,” says Prevost Director
of Marketing Michael Power. “We use AGM batteries that can take
repetitive deep discharges and have proven to be very durable over 400
cycles. These batteries require no maintenance. They are sealed and
He says AGM batteries are becoming more affordable and are readily
available, and last up to four times longer than lead-acid batteries.
A coach without PRIME
Typically, the alternators constantly charge the batteries, which
mean a constant parasitic load on the engine up to 14hp. Electrical
loads on the coach are directly linked to the engine, as conventional
lead-acid batteries need to be kept at optimal charge. An alternator has
a mean efficiency around 65 percent affecting fuel consumption up to
2.4 liters per hour. A vehicle on the road usually uses its engine on
compression mode between 10 and 30 percent of the time. These standard
batteries generally cannot endure deep discharges.
A coach with PRIME
The PRIME system detects negative torque on the engine and triggers
the alternators and the air dryer to charge the batteries and fill the
air tanks to provide engine braking. The system monitors battery
temperature to prevent overcharging and overheating and provides
information to the driver on the battery state of charge (SOC).
Voltage display does not change and notes SOC in percentage. Based on
the SOC, the software will determine if batteries need immediate
charging or can wait until the next zero load on the engine to trigger a
charge using free energy.
“This is a significant part of our continued effort to lower
operating costs for our customers,” Power says. “With PRIME, improved
fuel economy can be realized and good driving habits can even increase
that cost savings.”
There is also a new feature in the cluster. With the engine running
and the vehicle not moving, the percentage of trip made with regenerated
electricity shows in the cluster. This value resets when the engine
restarts. Prevost sees this as an incentive to the driver to adopt
fuel-efficient driving habits.
The instantaneous fuel consumption bar graph displays when the vehicle is in movement.
Benefits of PRIME
Increased fuel economy — The amount of fuel savings
depends on the duty cycle. According to Prevost, PRIME has an estimated
fuel savings of 2 percent. Prevost validated the results in real driving
conditions and with various duty cycles. Some test vehicles showed up
to 5 percent fuel savings. The maximum fuel economy will come when the
terrain of the road allows the batteries to charge only when the vehicle
is in free wheel. Batteries charge with free energy without dedicating
further fuel consumption.
Decreased lifecycle costs — While the price of absorbed glass mat
(AGM) batteries is about twice that of conventional lead-acid batteries,
their lifecycle is about four times longer than traditional batteries.
The cost of replacing lead-acid batteries is often viewed as a hidden
benefit of AGM batteries.
In AGM batteries the electrolyte is absorbed in a fiberglass mat
separator. This sealed battery requires no maintenance during its
lifetime. There is no danger of acid spilling and no need to add water.
New X3-45 Aluminum Baggage Bay Doors — New Prevost aluminum luggage
bay doors on the X3-45, which Prevost has tested in a very tough winter
environment over several years, are 38 percent or 265 lbs. lighter than
the previous product. The reduced weight helps to reduce fuel
consumption, especially for stop-and-go applications. The company says
the high quality structure has a solid feel compared to welded tube
structure along with an improved dent resistance — 2.6 mm aluminum
thickness compared to 1.3 mm stainless.
The Class A finish lends a brighter luggage compartment compared to
the dark grey of the previous doors. The redesigned door handle has the
lock integrated into the plastic casing.
“These aluminum components reduce the vehicle’s weight,” Power says.
“They are less expensive to replace, are easier to repair and improve
overall fuel economy and lifecycle costs.”
The aluminum doors also feature a new innovative door seal — a
one-piece with rounded corners and a multi-lip seal. This new water
management redirects water away from the inside of the baggage bay,
greatly improving water tightness. The seal installs easily without
using glue. An added deflector means there is no direct access to the
seal for water spraying from outside the coach. If water gets inside the
door handle, it drains outside the coach.
Bitzer compressor — The 4-cylinder Bitzer air compressor replaces the
Carrier 05G and mounts directly on the engine and is nearly 100 pounds
lighter. The relative positions of each pulley do not vary and the belt
span is shorter. This arrangement transmits vibration through the engine
mounts instead of the structure. With more capacity at lower RPMs and
engine idle speed, fuel economy improves two percent at 100km/hrs with
less load on the engine — 4HP less at 100Km/h (60 miles per hour).