Cobra Electronics CPI 2575 warranty Power Consumption, Ground Wiring

10276_CPI2575_PH1 8/20/07 2:33 PM Page 12

Power Consumption

Installation

Power Consumption

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For each piece of equipment you will be operating from the inverter, you must determine the battery’s reserve capacity (how long the battery can deliver a specific amount of current – in automotive batteries, usually 25 ampere) or ampere-hour capacity (a measure of how many amperes a battery can deliver for a specified length of time).

Example – Reserve capacity: a battery with a reserve capacity of 180 minutes can deliver 25 ampere for 180 minutes before it is completely discharged.

Example – Ampere-hour capacity: a battery with an ampere-hour capacity of 100 ampere-hours can deliver 5 ampere for 20 hours before it is completely discharged.

To determine the battery ampere-hour capacity you require:

1.Determine how many watts each piece of equipment consumes. This can normally be found on the product label. If only the current draw is given, multiply the current draw by 115 to get the watt consumption.

2.Estimate the time (in hours) that each piece of equipment will be running between battery charging cycles.

3.Calculate the total watt-hours of energy consumption (power x operating time) using the average power consumption and the total estimated running time (in hours). Power x Operating Time = Watt-Hours.

Laptop TV/VCR (up to 25") Blender

100 watts x 2 hours	115 watts x 3 hours	300 watts x 15 minutes
= 200 watt-hours	= 345 watt-hours	= 75 watt-hours

4.Divide the watt-hours by 10 to determine how many battery (12 volt) ampere-hours will be consumed.

Ground Wiring

Installation

Ground Wiring

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There is a screw on the rear panel for Chassis Ground. This is to connect the chassis of the inverter to ground.

The Chassis Ground Screw must be connected to a grounding point, which will vary depending on where the unit is installed. Use a #8 AWG copper wire (preferably with green/yellow insulation) to connect the chassis ground screw to the grounding point.

Chassis Ground

In a vehicle: Connect the Chassis Ground to the chassis of the vehicle.

In a boat: Connect to the Boat Grounding System.

In a fixed location: Connect the Chassis Ground Screw to earth ground by connecting to a ground rod (a metal rod pounded into the earth) or other proper service entrance ground.

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