I'm thinking of two stacked inverters for 240 ac for all input configurations. Has anybody done this?
Yes, many people have done this, some with more success than others. But your comment about "input configurations" gives me pause -- even a single 120-volt inverter can be used with "all input configurations." The purpose of stacking 120-volt inverters to make 240/120 split phase has to do with output, not input. As noted below, unless you need 240-volt output for some reason, there are all kinds of reasons why you are better off sticking with 120. Most stackable 120-volt inverters can be stacked to produce double the current at 120 volts, as well as the other way (same current but at 240 volts).
That model does not produce North American voltage, which is 240/120-volt split phase at 60Hz. You do not want this Tripp-Lite model unless you are building for overseas.
Those inverters are not legal in the US, and certainly not safe if "stacked" as shown in the eBay listing. The are not listed for RV use (or for any other use, near as I can tell), they can not be hard-wired so would have to be located at point of use (say, next to the coffee maker to run the coffee maker). More importantly, you can never, ever connect two separate plug-end cordsets to the same thing -- it's incredibly dangerous.
Besides that, even if they could be made safe and legal (they can't), these units are straight 240, not 240/120 split phase. Again, this is not the North American power standard, and unless everything on your coach is 240, there is no way to really make use of these. The "stacking" that these units provide (if illegally wired as shown in the drawing) is not to make 240/120 split phase out of multiple 120 units, but rather to simply increase current output at the single rated voltage.
There are stacking inverters and then there are legal and safe stacking inverters. Sean has the reasons, but I don't believe the stacking inverters in the link are safe or legal for our use. I think the main reason is the use of plugs for the AC output, I think they have to be hard-wired for permanent installations.
That's one reason, and it is one that makes most inexpensive low-output inverters unsuitable for bus conversions. You are not permitted to use a plug and cord to connect a hard-wired electrical system to an inverter, generator, or any other source with the sole exception of shore power at a properly listed inlet.
However, as I wrote above, these units are also not listed, and, worse, the connection diagram anticipates that you will use multiple plug-and-cord sets and gang the outputs together to connect to something downstream. It is never legal, and incredibly unsafe, to do this.
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If you care about codes I believe an inverter has to be certified for RV use. I'm pretty sure those Ebay models are not certified for RV use.
I am quite certain they are not, and as I wrote earlier, they do not appear to carry any listing at all, making them unlawful for almost anything. But that is the nature of eBay, where you can no longer buy a legal firearm, but you can buy all manner of other crap that can't legally be used in this country.
I'm wondering why you would need 240 volt in a bus unless you are doing 240 volt air conditioning? I converted my generator from 240 volt to 120 volt because the generator doesn't like the load unbalanced when doing 240 volt.
This would be my question as well. As I wrote way up top, unless you have 240-volt loads, you're better off stacking inverters (if you even need that much capacity) to produce straight 120. From an input standpoint, the only reason you would need to stack inverters to 240 is if you needed more than 6kW of inverters, and even then, only if you actually need them to pass-through that amount.
As Glenn wrote, without knowing a little more about your plans, it's hard to know what to write.
-Sean
http://OurOdyssey.BlogSpot.com
