Cobra Electronics CPI M400 - Manual (Page 8)

11 Nothing comes close to a Cobra ®
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 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.
4. Divide the watt-hours by ten (10) to determine how many power supply’s
(12 volt) ampere-hours will be consumed.
10 English
CAUTION Reverse polarity connections (positive to negative) will blow internal
fuses in the inverter and may permanently damage the unit. Such damage is
not covered by the warranty.
CAUTION Remove any jewelry (watch, ring, etc.). Be careful not to short circuit
the battery with any metallic object (wrench, etc.).
WARNING You may observe a spark when making the connection because
current can flow to charge the capacitors in the inverter. Do not make this
connection in the presence of flammable fumes. Explosion or fire may result.
Thoroughly ventilate the battery compartment before making this connection.
Installation
Connecting Cables
Installation
Power Consumption
300 Watts x 15 minutes
= 75 Watt-Hours 115 Watts x 3 hours
= 345 Watt-Hours
Blender TV/VCR (up to 25")
100 Watts x 2 hours
= 200 Watt-Hours
Laptop