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Old 11-21-2019, 09:34 AM   #1
Join Date: Jul 2019
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Year: 2003
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Am I doing this right?

I'm diving into the electrical this week and thought I had it figured out but now not so sure.

I have 3-100ah AGM batteries. I have ordered the Renogy 2000w inverter/charger.

Shore power, battery isolator, 350watts solar (eventually)

Our only AC draws for now, will be laptop+monitor, and charging tool batteries. Everything else (4 led lights, natures head, maxxair, water pump, 12v outlet) will be on my DC system

My initial thought was to buy a larger watt inverter to have room to grow our system, but now I'm concerned we don't have the battery AH to support it. I don't think we'll be drawing enough AC with just the computer/laptop/but I'm having a hard time understanding the extra draw the larger the inverter?

So, I'm looking for reassurance that this inverter will be OK, or someone to tell me I have it all wrong and go smaller.

Any help much appreciated!
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Old 11-21-2019, 10:07 AM   #2
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Join Date: May 2016
Location: Minnehaha Co., SD
Posts: 802
Year: 1996
Coachwork: Amtran
Chassis: International
Engine: DT466
Rated Cap: 65
We've got a 2000w inverter, with a 690ah battery bank (golf cart batteries, so maybe 345ah effective capacity) and we run our laptops, refrigerator, some lighting, occasional power tools, and sometimes even our water heater. I've only ever overloaded the inverter when I was trying to use a tool that has a high draw at startup (chopsaw, air compressor, etc).
It doesn't sound like there's any reason for you to go any larger on the inverter. I've heard that 2000w is the largest you'd want to go on a 12v system because of internal battery resistance or some such thing.
I'm not that well versed in electrical systems, so I can't speak to the battery capacity as it relates to inverter. I do know there's a trick to balancing battery capacity and solar panels though. It sounds like you'll be fine regarding your inverter, though, unless you're planning on welding or something.
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Drew Bru is offline   Reply With Quote
Old 11-21-2019, 11:11 AM   #3
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Join Date: Nov 2016
Posts: 1,146
The actual load drawn in Ah per minute is largely determined by the end load device, not the intermediate inverter/converter.

Huge current draw not only drains a small bank quickly, but voltage sag may be critical, depends on battery chemistry & quality, but primarily on Ah capacity.

For cost vs quality, and especially efficiency, I prefer a collection of small PSW inverters sized just big enough for those few load devices I really can't find in DC-native models.

Wire them so they turn on and off with the device powered, don't just leave them running.

A 200W load powered by a 2000W inverter will waste **a lot** of energy. But efficiency only matters off grid mostly-solar. . .

If shore power is available or a genset is running, then who cares?
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Old 11-21-2019, 05:23 PM   #4
Bus Crazy
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Originally Posted by leoodood View Post
Our only AC draws for now, will be laptop+monitor, and charging tool batteries.
I would go direct DC for all of those, no inverter at all needed.

If optimizing efficiency is a goal.
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