Duracell Digital inverter 400 Owner's Manual page 26

Here are some guidelines that will help to preserve your battery:
• Vehicle batteries are not designed for repeated deep-discharge
cycles, and constantly recharging a vehicle's battery will shorten its
life. Therefore, when you are using a vehicle battery as a power
source, start the vehicle every hour or two to recharge the battery.
• The Inverter will operate while the engine is running, but the
voltage drop that occurs when the engine starts may trigger a low-
voltage shutdown.
• Vehicle batteries are designed to provide brief periods of very high
current needed for engine starting. They are not intended for
constant deep discharge. Regularly operating the Inverter from a
vehicle battery until the low-voltage alarm sounds will shorten the
life of the battery. Consider connecting the Inverter to a separate
deep discharge-type battery if you will be frequently running
electrical products for extended periods of time.
• If you are not going to use the Inverter for a few days, turn off the
unit. The inverter draws 0.3 A or less when the unit is on and no
load is connected, but it will eventually discharge the battery.
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