Samlex America SSW-2000-12A - Manuel (Page 11)

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Section 4 | oPeRAtinG tiPS
DETERMINING BATTERY SIZE
The power inverter will require DEEP CYCLE lead acid batteries of appropriate capacity.
The automotive SLI (Starting/lighting/Ignition) battery is not designed for repeated deep discharge. The
SLI battery may not supply enough energy and its service life may be reduced.
To determine the minimum battery size that you will need to operate appliances, follow these steps:
1. Determine the AC wattage of each appliance and / or tool you will need to simultaneously
operate from the inverter. To do this, read the labels on the equipment to be operated. Usually,
power consumption is shown in Watts. If it is shown in Amps, multiply by 115 to determine the
AC wattage.
2. for each appliance, estimate the number of hours the appliance will be in use between
battery recharges.
3. for each appliance, determine the Watt-Hours of energy required by multiplying the AC wattage
by the number of hours of use.
4. Add the Watt-Hours of energy for each appliance to get the total Watt-Hours of energy for all
appliances to be used.
5. Divide the total Watt-Hours of energy on the AC side by 10 to get the total Ampere-Hour of energy
on the 12 VDC side to support the operation of the appliances.
6. The Ampere-Hour (AH) capacity of the battery should be 2 times the total Ampere-Hour energy
required on the 12 VDC side to support the operation of the devices (as calculated at step 5 above).
Two times factor is necessary because batteries are normally not discharged below 50% capacity.
To get an estimate of the current (in Amps) that the battery is delivering, divide the load's AC
consumption power (in Watts) by (10).
Keep in mind that most appliances are not operating for long periods of time. for example, a typical
home-use coffee maker draws 500 Watts during its brew time of 5 minutes, but it maintains the
temperature of the pot at about 100 Watts. Typical use of a microwave is only for a few minutes,
sometimes at low power. Some exceptions to brief operating times are TVs, computers etc.
In most instances, the inverter can be left connected to the battery when not in use, make sure power
switch is in the OFF position.
battery performance drops in low temperature environment. Higher capacity batteries should be
installed if the environmental temperature is below 20 o C.