Cobra Electronics CPI 850 - Manual (Page 9)

13 Nothing comes close to a Cobra ® 12 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 115 volt AC power is potentially lethal.
Do not work on AC wiring when it is connected to
the inverter (even if it is switched off) unless the
DC power source is physically disconnected from
the inverter. Also, do not work on AC wiring if it is
connected to another AC power source such as
a generator or the utility line.
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.
Power and
Protection Indicators
Operation
Operating Limits
Operation
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.
4. Divide the watt-hours by 10 to determine how many
power supply’s (12 volt) ampere-hours will be consumed.