While the converter will attempt to provide power to your 12VDC components without a battery installed; high demand items like the water pump; slide motors; landing gear and stabilizer motors; and furnace can demand more amps than the converter can manufacture and maintain 12VDC. The converter depends on the battery to make up the difference to maintain that voltage. Without the battery, that converter can "fry" itself trying. Again, this process can be easily seen with a battery monitor system that displays amp flow.
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