Inverter size on truck

[Heavy_Chevy]

Need a sanity check here. 2005 Silverado 2500HD 8.1/Allison with dual battery and isolator setup, I’m upgrading to a 250 amp alternator and 0 gauge pure copper wire setup. If my memory serves correct, that means the truck can put out a max of 2500 watts of continuous power, so I wouldn’t need an inverter any bigger than 2500 watt continuous since the truck can’t produce more than that.... correct??

[Heavy_Chevy]

Nevermind! Found it! About 3000w continuous for anybody wondering.

[ChuckS]

Ohms law and you can easily calculate amps to watts...

[Devin_Noel]

Your battery can output more than your alternator. So you can put in an inverter that draws more than your alternator. But if you were tapping the inverter for more than your alternator could output it would drain the battery. Not a big deal for brief usage, but a bad idea for continuous usage.

[JRTJH]

Also keep in mind that your alternator/voltage regulator output is not 12 VDC. It's anywhere from 12.8 to 14.6 VDC

At 12.8 VDC, 250 amps is 3200 watts, while at 14.6 VDC, that same 250 amps is 3650 watts.... Also, most alternator/voltage regulators are not rated at "maximum amps continuous" but are rated at "maximum amps for a period of time. You'll have to dig "deep into the specs" to get to the "continuous alternator/voltage regulator output... This statement is from one "reliable source": It is not uncommon for a 160 amp alternator to have a continuous duty cycle of less than 90 amps.

So, your 250 amp HD alternator may or more likely, may not have a "continuous output of 250 amps, and it "could be" that even though the alternator is rated at 250 amps, the voltage regulator may have a lower "maximum rating" or may have a different "continuous duty cycle rating".... It boils down to "what is the weakest link"....