Inverters are sized to the expected loads. Batteries are sized to how long you want to run those loads.
Example: My wife’s hair dryer on 500 watts is drawing about 50 amps. If she ran it for an hour that would be 50 amp/hours, which would be all you can use out of a 100AH battery. Thanks to Peukert’s equation, with lead acid batteries it is a little worse than that. (heavy loads draw them down faster than the formula, light loads a little less than the formula) As for the switches, I don’t know how your boat is wired. My inverter runs off the house bank with its own switch. BTW – your math is a bit off. A 100 amp hour battery can probably supply around 500 amps or more, which is 6,000 watts. It can’t do it for very long though, but long enough to start an engine. Amps, amp-hours, watt-hours, and so on can get confusing. I’ll post how to figure this out when I get a chance. Joe From: CHARLES SCHEAFFER via CnC-List <cnc-list@cnc-list.com> Sent: Tuesday, October 17, 2023 4:03 PM To: CNC boat owners, cnc-list <cnc-list@cnc-list.com> Cc: CHARLES SCHEAFFER <cscheaf...@comcast.net> Subject: Stus-List Sizing an inverter OK, an DC/AC Pure Sine Wave inverter looks attractive I've heard some boats have 1000 watt, some 2000watt and some 3000 or more. What size inverter is right for a boat equipped with two 100Ah AGM batteries? One battery provides 12v x 100ah: 1200watts. My system can provide 2400 watts but I usually reserve one battery to restart the engine and run on the other battery. Does the inverter get fed from a bus common to both batteries, or to the selector switch marked, "Off, 1, both, 2"? Thanks, Chuck S
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