Cobra Electronics CPI 475 owner manual Power Consumption, Operation Power On and Off

On/Off Switch to On

10272-CPI475_PH2.qxd 7/9/07 11:30 AM Page 10

Installation	Power Consumption	•
Power Consumption

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 amperes) 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 amperes 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 amperes 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

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

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

Operation Power On and Off

Turning Your Inverter On or Off •

Be sure to have your power inverter properly installed before attempting to turn the unit on (see installation page 5).

To turn the power inverter on:

1. If a DC power supply is being

used as the power source, switch

it on.

2. On the left side panel, switch the On/Off Switch to on.

The inverter is now ready to deliver AC power to your loads. If several loads are to be operated by the inverter, turn them on separately, after the inverter has been turned on. This will ensure that the inverter does not have to deliver the starting currents required for all the loads at once.

On/Off Switch to Off To turn the power inverter off:

1. On the left side panel, switch the On/Off Switch to off.

NOTE The On/Off Switch turns the control circuit in the inverter on and off. It does not disconnect power from the inverter.

When the switch is in the off position, the inverter draws no current from the battery. When it’s in the on position, but no power is being supplied to the load, the inverter draws less than 500 milliamperes from the battery. This is low current draw. It would take more than a week to discharge a 100 ampere- hour battery at this rate depending on the age of the battery.

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