Inverter Voltage Drop

emily_06emily_06 Registered Users Posts: 1
Hi all!

I have a 100amph 12v battery and a 2000W inverter charger for my RV. I am trying to run a 1600W appliance off it. My wire sizes are 0 guage and i have checked the connection points.

Before running the appliance the inverter is seeing 13.2v from the battery. Once I run my appliance it drops the voltage to lower than 10volts which trips my inverter to turn off. 

I am assuming this is because of my battery size, but I was hoping someone could help me size the new battery bank and or confirm this is my problem!  My understanding is that 1600/12=133amps. as I only want to use this appliance for 10 minutes - this is 22 amph. so it should be within the available 50amph available power supply?

Thanks in advance!


  • EstragonEstragon Registered Users Posts: 4,451 ✭✭✭✭✭
    Assuming it's a flooded lead acid "deep cycle" type battery, the 100ah rating will be at something like a C/20 (20hr) rate.  That's about a 5a steady load.

    The current drawn will increase as voltage drops, eg 1600w ÷ 85% inverter efficiency ÷11v = 171a.  Drawing 130-179+ amps is a much faster rate, which will make the apparent capacity lower.  Depending on the load and the inverter, there may be other losses as well.

    My guess is something like a 400ah bank would be needed to run the load reliably, which would be more like a C/3 rate.  Another possibility would be to dedicate a different type of battery (eg lithium or starting-type AGM) made for high-current discharging to this load.

    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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