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Old 05-13-2019, 09:40 PM   #1
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Any Advantage To 2 Inverters?

Since I plan on welding capabilities on the bus and I have 2 inverters whether setting one up in the garage and one for the house electric would be any advantage. I suspect an advantage is only gained if I also have separate battery supply to the extra one.
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Old 05-14-2019, 01:11 AM   #2
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They both could share the same battery bank. Having your garage on its own inverter does sound like a decent idea. It also gives you some redundancy.
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Old 05-14-2019, 05:08 AM   #3
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Good question Marc but... difficult to answer.

I'm not sure what size inverter would be required for welding (or if it's even possible) so just brainstorming here. I'll assume that a big inverter is required (3000-5000 watt).

Several factors are at play. Inverter efficiency is a big one. I believe in the ideal world, an inverter would be sized to operate at its peak efficiency and would be located as close to the battery bank as possible. Of course, for our style use, the power draw is not usually consistent which makes sizing for peak efficiency difficult/impossible (think of a refrigerator with a 50% duty cycle or worse, a microwave that is only used 2 minutes per day).

Inverters also have a current draw, even when doing nothing. Depending on the inverters, two might waste a lot more power than one - or two might be much better. The larger/modern/name brand inverters have some interesting 'standby' modes now that may reduce this consumption to a very low level. None of those work for me as I have a constant 120VAC power draw but it might be useful for some. I can't remember the old rule of thumb (pre-smart standby mode) but seems like it was 1% of rated output?? Someone please correct me if wrong.

Cable size and voltage drop is very significant with any inverter and when talking about large ones (2000 watts) and a 12VDC battery bank, you quickly become very limited by cable length. That said, there may still be an efficiency advantage to multiple inverters even with them located side by side next to the battery bank.

To decide, I think I'd lay out my 120VAC electrical system with a careful eye towards which accessories will need power all the time vs occasional use. If you could power the former with a small inverter and the latter with a larger inverter that is only turned on when needed, it might be worth doing.
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Old 05-14-2019, 06:31 AM   #4
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A lot of people use a small inverter for their fridge. It runs all the time and is more efficient. The big one comes on for intermittent larger loads.
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Old 05-14-2019, 10:41 AM   #5
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Good post JD--I'm not sure about the welder either.
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Old 05-14-2019, 11:43 AM   #6
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These are the 2 inverters I have. Just realized the 3500/7000 is a modified sine wave as opposed to my 3000/6000 that is pure sine wave. The welder I have is 110v, 35-88amp output.
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Old 05-14-2019, 02:31 PM   #7
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I have two inverters in my bus. A small one by the driver's leg on the wall for charging phones and running a laptop, etc..


a bigger one I will mount by the kitchen for running a blender or maybe a toaster oven.


I know converters [[from 120VAC to (x)VDC]] use power just by plugging them in. My inverters [[from 12VDC to 120VAC]] have fans that use power, so running two at a time may be wasteful. Not sure if a bigger one "wastes" more power than a smaller one, but I will go with that assumption until I know different. So I use my small one, until it won't kick-over the motor or shows an overload.


I'm always for modular. Especially when things interchange (think Apollo 13)



They used to make 12V welders that you could find for sale in the back of 44 magazines. Nice to be able to fix your rig on the trail. They required larger alternators, from what I remember. That was 25 years ago, though!
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Old 05-14-2019, 03:41 PM   #8
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Quote:
Originally Posted by Mountain Gnome View Post
I have two inverters in my bus. A small one by the driver's leg on the wall for charging phones and running a laptop, etc..


a bigger one I will mount by the kitchen for running a blender or maybe a toaster oven.


I know converters [[from 120VAC to (x)VDC]] use power just by plugging them in. My inverters [[from 12VDC to 120VAC]] have fans that use power, so running two at a time may be wasteful. Not sure if a bigger one "wastes" more power than a smaller one, but I will go with that assumption until I know different. So I use my small one, until it won't kick-over the motor or shows an overload.


I'm always for modular. Especially when things interchange (think Apollo 13)



They used to make 12V welders that you could find for sale in the back of 44 magazines. Nice to be able to fix your rig on the trail. They required larger alternators, from what I remember. That was 25 years ago, though!
l found that interesting so I did a bit of a search - you can buy 12V welders in North America for $700 - $1000 - I also checked Alibaba - ususally when you buy from them you have to order 100's or 1000's of an item, but with the 12V welders you can order as few as one - from the looks of it, at least some of the 12V welders they are selling for as little as $40 are the same as the much higher priced ones sold here

https://www.alibaba.com/showroom/wel...chine-12v.html
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Old 05-14-2019, 04:21 PM   #9
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Originally Posted by Sleddgracer View Post
l found that interesting so I did a bit of a search - you can buy 12V welders in North America for $700 - $1000 - I also checked Alibaba - ususally when you buy from them you have to order 100's or 1000's of an item, but with the 12V welders you can order as few as one - from the looks of it, at least some of the 12V welders they are selling for as little as $40 are the same as the much higher priced ones sold here

https://www.alibaba.com/showroom/wel...chine-12v.html
*drool*
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Old 05-14-2019, 06:54 PM   #10
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Quote:
Originally Posted by Sleddgracer View Post
l found that interesting so I did a bit of a search - you can buy 12V welders in North America for $700 - $1000 - I also checked Alibaba - ususally when you buy from them you have to order 100's or 1000's of an item, but with the 12V welders you can order as few as one - from the looks of it, at least some of the 12V welders they are selling for as little as $40 are the same as the much higher priced ones sold here

https://www.alibaba.com/showroom/wel...chine-12v.html
It isn't till the order is being placed that you find out that one item coming from China is $400 in shipping and you might get it in 3 months.
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