Alternator and wattage of inverter (1 Viewer)

[skiberg]

My calculations, based upon AI assistance, suggest we can handle about an 1800 watt power inverter without changing alternator. For those of you that have added an inverter without changing alternator, how successful have you been?

 

[WTITW]

Are you (or the ai model you relied on) simply multiplying 150amps by 12 watts and arriving at 1800watts? That doesn’t account for the trucks loads or the unfortunate fact that the denso alternators used by oem only put out like 60 amps at idle. @r2m has a 3k inverter, but also has HO alt and dual battery.

 

[jeremy j]

I was doing something similar since I have the 800 watt ecoflow fast charger. I used this as the max load on the alternator. It seems pretty extreme and really never have all this going at once.

• Rear defogger: 15–20 A
• Seat heaters (2 front + rear): 15–25 A
• Cooling fans (high): 20–30 A
• Headlights & HVAC & electronics: ~60–80 A
• Total peak: ≈ 110–130 A

I generally run my DC charger at 400 watts. That's a little over 30 amps. I didn't feel comfortable running it at 60+ amps without upgrading the alternator. I am only charging a 1kwh battery so 400 watts charges plenty fast for me.

 

[MallCrl]

Realistically, for any significant duration, I wouldn't surpass a 600-650 watt draw at idle, maybe 800 watt at driving speed; and those figures are assuming you have the 3 zone AC with the 150A alternator. An inverter outputting 800 watts on the AC side will generally be drawing ~910 watts on the DC side (assuming 88% efficiency).

Theoretically you could increase that number slightly with an AGM battery and a VoltageBoosterPro, since the voltage will be slightly higher (thus reducing amps at a specific watt output); but really if you want to be powering an 1800 watt inverter at full output you'll need something that can happily output 160A or more. You may get away with that with a high output 270A alternator at idle, but it's going to be generating some serious heat after a while. Ideally, to draw that much you would want to be pulling it from a 200Ah or larger LiFePO4 aux. battery.

The better question here, is what are you actually trying to power

 

[skiberg]

Helpful. Thanks. Sounds like it makes sense for a 2nd battery and upgraded alt. I hope to power blender, fridge, toaster , small micro. basically to make breakfast/lunch on the road. I’m somewhat of a neophyte on the electrical side of things.

 

[MallCrl]

For the fridge you'd be much better off running a 12v fridge, as almost all the 120v fridges require the fridge/vehicle to be level (or near it) to work, and draw way more power.

Toaster will probably draw the most, but even a ~700w microwave will still draw upwards of 1000w when operating.

To correct and efficiently power those kinds of loads, you're looking at a secondary battery and, depending on the amount of driving you're doing daily and solar you have, a beefed up alternator to support higher amperage DC-DC charging as well

 

[r2m]

As Jake said above, I upgraded to a 240 watt alternator for my 3k pure sine inverter. But I also have a winch, lights, compressor, etc.
If you have the budget, just get a high output alternator, especially if you're adding accessories above and beyond your inverter.
I purchased mine from here: Tucson Alternator Exchange & Copperstate Auto Electric - https://www.tucsonalternator.com/Default.aspx