Challenge IN350 Instruction Manual page 13

What battery should I choice?
For low power inverter or for a short use (10 minutes) of high power
inverter at the maximum load, a standard 12V vehicle (50/75A) battery can
supply the sufficient energy.
If you want to use high power inverter at maximum power for long time, we
recommend you use deep cycle (marine) batteries which are suitable for
hundred complete charge/discharge cycles. If you use the normal vehicle
starting batteries they will be drained out after a dozen charge/discharge
cycles. If you do not have a deep cycle battery, we recommend that you
run the engine of your vehicle when operating the power inverter to
avoid draining the battery.
If the vehicle battery is utilized for an extended period with maximum load,
the battery voltage may be drained to the point where the battery has
insufficient power to start the vehicle. In this case it is recommended to use
a deep cycle batteries cabled to the automotive starting battery via a
battery automatic isolator between the batteries which ensure that the
batteries are automatically charged but that the electric circuit of the
vehicle is switched off when the inverter in use. This type of battery is
commonly found in caravans, motor homes, recreational vehicles and
boats. Consult your automobile professional whenever in doubt.
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