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form CI386-141
Telma Equipped Braking System for
Medium and Heavy Duty Trucks
It has been noted depending on the vehicle’s electrical needs, the Telma model used, and the vehicle vocation
that an electrical system upgrade is necessary. As an example, a high-amp alternator and 4 group-31 high
cycle batteries (900CCA) would require a system upgrade.
The Electric Drive-Line Brake retarder requires high amperage thus placing high demand on all charging system
components. Proper battery capacity, and proper ratings for the alternator, circuit protection, and cabling are
required for proper operation and to ensure the reliability of the Electric Drive-Line Brake retarder, the
alternator, and the vehicle’s accessories.
Wilson recommends an alternator rated at no less than 200 amps in applications equipped with Electric DriveLine Brake Retarders. Alternators rated from 240 to 320 amps may be required depending upon the vehicle
type, application, duration of electric brake retarder used, as well as the amperage needs based on other
vehicle accessories (see Sizing Chart for Alternators on reverse). Cabling and protective devices, within the
charging circuit, must be properly sized for the alternator’s maximum output rating. A misdiagnosis or
alternator failure may occur if cables and protective devices are not properly sized. Improperly sized circuit
components may also lead to short battery life, low voltage, and poor Electric Drive-Line Brake Retarder
performance.
Installation of a Wilson alternator in applications with a Telma Electric Drive-Line Brake Retarder requires the
selection of an alternator with an amperage rating and the circuit components properly sized for the Telma
equipment as well as all other vehicle accessories. Currently there are over 40 Telma models available in the
market place, each model with various amp draws ranging from 10 amps per phase to 80 amps per phase
with 4 phases per system.
Alternators rated at less than 200 amps and/or circuits not properly sized for a Telma Electric Drive-Line Brake
Retarder may be found in service. Upgrades to the properly rated alternator and circuit components must be
made in these instances to assure proper functioning and reliability of the Electric Drive-Line Brake Retarder
and other electrical system components.
See Sizing Chart for Alternators on reverse -
www.wilsonautoelectric.com
Sizing Chart for Alternators
Typical
Current/Amp
Rating
CAB
Heater/AC Blower Motor - 4 (high)
24.00
Key On All Loads Off (Default 1 Qty) 10.00
A/C Compressor Clutch
4.40
Interior Lights
2.00
Mirror Heater
9.00
Windshield Wiper (high)
10.00
Qty
x
x
x
x
x
x
=
=
=
=
=
=
Total
SLEEPER
Bunk Fan (Select only ONE)
High
Bunk Heater
Lights
15.00
12.00
2.00
x
x
x
=
=
=
Total
AUDIO EQUIPMENT
AM/FM Radio
CB
1.00
1.00
x
x
=
=
Total
ACCESSORIES
Electric Blanket
Refrigerator (Cooler Style)
Television & Video
3.00
4.50
3.00
x
x
x
=
=
=
Total
BATTERIES
Battery @ 8 amps each
8.00
x
Typical
Current/Amp
Rating
Total
Current/Amp
=
Total
LIGHTS ON TRACTOR
4 - Hi Beam
Daytime Running Lights
Clearance Marker Lights
LED Light (# of LIGHTS)
Incandescent Light (# of BULBS)
Brake Lights
LED Light (# of LIGHTS)
Incandescent Light (# of LIGHTS)
Turn Lights
LED Light (# of LIGHTS)
Incandescent Light (# of LIGHTS)
Fog/Driving Lamps
Tail Lamps
Total
Current/Amp
Qty
14.00
x
=
0.08
0.30
x
x
=
=
0.50
2.20
x
x
=
=
0.75
2.20
x
x
=
=
5.00
15.60
1.00
x
=
x
x
=
=
Total
LIGHTS ON TRAILER
Clearance Marker Lights
LED Light (# of LIGHTS)
Incandescent Light (# of BULBS)
Brake Lights
LED Light (# of LIGHTS)
Incandescent Light (# of LIGHTS)
Turn Lights
LED Light (# of LIGHTS)
Incandescent Light (# of LIGHTS)
Tail Lamps
0.08
0.30
x
x
=
=
0.50
2.20
x
x
=
=
0.75
2.20
x
x
=
=
1.00
x
=
Total
TOTALS
CAB
SLEEPER
RADIOS
ACCESSORIES
BATTERIES
LIGHTS ON TRACTOR
LIGHTS ON TRAILER
=
=
=
=
=
=
=
Grand Total
Total Electrical Load
Total Amperage @ Idle (80% of total elec. load)
*Note - amps are all estimated values and should be used as a guideline only
Values may vary, depending on vehicle.
www.wilsonautoelectric.com
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