I might have bought the wrong inverter...

I'm super new. I watched a lot of videos and read a lot, as I was planning my new camper van system, which I want to be power fairly large AC loads. Most people said to buy the biggest inverter you can afford. Okay, so I bought a 4000-watt 12v Giandel. I thought that 24v wasn't for beginners, and I already have some 12v appliances. Also, I will be using a DC to DC charger to charge my batteries with the alternator while I drive (quite a bit); if I had gone with a 24v system, I heard that this can become problematic with alternator charging. Then I started reading more on this forum and saw that most people say 2000-watt, 3000-watt, higher should be on 24V systems. SO....my question is: should I keep the 4000w 12v Giandel inverter and make it work, knowing that my cables and other equipment are going to be large and expensive? Besides that, why/how is it that much of a problem? Or should I sell the inverter and start over with something smaller? Or maybe learn about 24v systems and move in that direction? Thank you very much! I know I have a lot to learn and I really appreciate your input.

When you say camper van, I am thinking Sprinter. What van is it exactly? I ask as 4000w is a lot of power. Even more so if you have no AC to run off it as most vans of such have none.
There are pros and cons to every voltage. While with 12v you will have larger cable sizes true, you will not have to add additional equipment and/or additional equipment will be more readily available. So there are pros and cons to each voltage whether it be 12v, 24v, or 48v. They all equal out, sort of.

The biggest inverter you can afford is not correct. You need to take into consideration of inefficiencies as well as parasitic draw. If you come back and say you will only draw at most 1200 watts than the unit you choose is not applicable.

Plenty will help here but need more details as in the van size, loads you plan to run, how you plan to charge etc.

Jennifer-3456 said:

I'm super new.

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Welcome!

Jennifer-3456 said:

Okay, so I bought a 4000-watt 12v Giandel.

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That's a lot of juice at 12v

Jennifer-3456 said:

I thought that 24v wasn't for beginners,

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Not true

Jennifer-3456 said:

and I already have some 12v appliances. Also, I will be using a DC to DC charger to charge my batteries with the alternator while I drive (quite a bit); if I had gone with a 24v system, I heard that this can become problematic with alternator charging.

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You would need a 12 to 24 boost converter.

Jennifer-3456 said:

Then I started reading more on this forum and saw that most people say 2000-watt, 3000-watt, higher should be on 24V systems. SO....my question is: should I keep the 4000w 12v Giandel inverter and make it work, knowing that my cables and other equipment are going to be large and expensive? Besides that, why/how is it that much of a problem?

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That's mostly it. 4000 watts at 12 volts is 383 amps when you include a nice round 85% efficiency number.
That means a 400 amp fuse and cabling to support it. That's something like two 0000 cables or getting into the MCM stuff.
It's heavy and expense just for the cables, fuses, breakers, etc.

Plus your battery bank would need to support a 400 amp load.
Many off the shelf 12 volt lifepo4 batteries are rated for 100a max draw and recommend something like 30-60 amp. So multiple batteries in parallel.

Jennifer-3456 said:

Or should I sell the inverter and start over with something smaller? Or maybe learn about 24v systems and move in that direction? Thank you very much! I know I have a lot to learn and I really appreciate your input.

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I'd start with a thorough energy audit. What do you need to run? How much does it run? Also, how much driving will it take to recharge?

One more thing to consider is that larger inverters tend to have larger idle power draws.

It will be OK as long as you never expect to actually get 4000W out of it. Really, calling it 4000W is a scam, but if you don't put more than a 1000W load on it, it should perform normally.

The real problem here is advertizing and hype. Somebody makes a perfectly good 1000W inverter and tries to sell it. Some competitor wants you to buy their inverter instead, so they claim it can output 1500W. You think, gee, a 1500W inverter must be better than a 1000W inverter? So, the numbers get ratcheted up higher and higher.

How do you know what's for real and what's a scam? Check if it is UL listed. UL doesn't determine quality, it determines safety. UL will determine if a unit is "SAFE" to operate. Most likely, UL will decide that pulling almost 400A out of a battery is NOT going to be safe. Most likely, you can't even convienently buy the size of wire that can safely carry that many amps.

Personally, I would get rid the the Giandel and start over. Don't buy anything else until you've fleshed out a complete plan.

What are you running for 120V devices?

I can live full time on a 1200W Giandel
My 1000W inverter won’t start the vacuum. 1200W does.
My 2000W Reliable/QZRELB inverter will run everything, too.

You need to know your continuous watts and high wattage needs. Then a good recommendation on inverters can be made. I originally calculated my needs and determined I could use a 1200W inverter. And I did for several years.

400bird said:

Welcome!

That's a lot of juice at 12v

Not true

You would need a 12 to 24 boost converter.

That's mostly it. 4000 watts at 12 volts is 383 amps when you include a nice round 85% efficiency number.
That means a 400 amp fuse and cabling to support it. That's something like two 0000 cables or getting into the MCM stuff.
It's heavy and expense just for the cables, fuses, breakers, etc.

Plus your battery bank would need to support a 400 amp load.
Many off the shelf 12 volt lifepo4 batteries are rated for 100a max draw and recommend something like 30-60 amp. So multiple batteries in parallel.

I'd start with a thorough energy audit. What do you need to run? How much does it run? Also, how much driving will it take to recharge?

One more thing to consider is that larger inverters tend to have larger idle power draws.

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Hello 400bird,

Thank you very much for your notes! I'm not seeing what the huge problem is if I am willing to spend more money on larger cables, etc., I have the space for them, and I get the right parts to support the 4000-watt inverter, like the 400-amp fuse. -- I planned on starting with two 206-amp hour lithium iron phosphate batteries wired in parallel, and then probably getting another down the road. The part I don't understand about what you wrote is that my battery bank would need to support a 400-amp load. How does one determine if this is true? Is it by the maximum charge that the battery can take (as stated on the manufacturer spec sheet)? The batteries I plan on buying can take a maximum charge of 50 amps.

All that being said, I'm probably going to try to sell my inverter and get are smaller inverter/charger. Thanks again---and in advance if you have the time to offer more of your thoughts.

MrThisIsME said:

When you say camper van, I am thinking Sprinter. What van is it exactly? I ask as 4000w is a lot of power. Even more so if you have no AC to run off it as most vans of such have none.
There are pros and cons to every voltage. While with 12v you will have larger cable sizes true, you will not have to add additional equipment and/or additional equipment will be more readily available. So there are pros and cons to each voltage whether it be 12v, 24v, or 48v. They all equal out, sort of.

The biggest inverter you can afford is not correct. You need to take into consideration of inefficiencies as well as parasitic draw. If you come back and say you will only draw at most 1200 watts than the unit you choose is not applicable.

Plenty will help here but need more details as in the van size, loads you plan to run, how you plan to charge etc.

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Thanks for taking the time to reply. I'm thinking all of this through.

Jennifer-3456 said:

The part I don't understand about what you wrote is that my battery bank would need to support a 400-amp load. How does one determine if this is true?

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4000 watts / 12 volts x 85% efficiency = something like 400 amps. When running a 4000 watt load, your inverter will pull roughly 400 amps from the battery

Jennifer-3456 said:

Is it by the maximum charge that the battery can take (as stated on the manufacturer spec sheet)? The batteries I plan on buying can take a maximum charge of 50 amps.

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The same spec sheet should have maximum (and possibly recommend or continuous) discharge in amperage. If the battery charges at 50 amp, it is probably rated to discharge at something like 50-100 amps.
With that discharge in mind, you would need 4-8 of those batteries to run a 4,000 watt load.

Jennifer-3456 said:

All that being said, I'm probably going to try to sell my inverter and get are smaller inverter/charger.

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I would! I agree with what others have posted 4,000 watts is likely overkill for your needs and is probably a flat out lie by the vendor.

Jennifer-3456 said:

Thanks again---and in advance if you have the time to offer more of your thoughts.

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Glad to help! Good luck!

Jennifer-3456 said:

Thanks for taking the time to reply. I'm thinking all of this through.

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Before you get carried away worrying lets just take a look at the maximum wattage appliances you are going to use.

Yes you may have bought the wrong size inverter for a 12v system but if you are unable to return it then lets look at the next best option.

So do you have a 4000/8000 watt inverter or a 2000/4000 watt inverter. There is a huge difference, I suspect it is the latter and if this is the case then then you need to wire for 2000 watts not 4000 as the 4000 is the surge current it can handle. Once you have confirmed this then we can move forward to help you.

Tim