inverters

[bevans6]

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.

Brian

[Kenny]

Some of the Magnum inverters can be stacked for 240 volt - Kenny

[Tenor]

Tony, Welcome to the madness!!

If you would tell us more about what you would like to do with your coach, we could really help more.  Things like how much you want to spend, where you plan to go, how often do you expect to use it, do you only go places that has electricity, what appliances you plan to install and what do they run from (example: fridge - gas, AC or 12vDC).  We love to help, but we often spin our wheels when we have nothing to grip!   

Glenn

[belfert]

Brassman
 They make inverters that produce/use 240 volts
http://www.tripplite.com/en/products/product-series.cfm?txtSeriesID=818

All of those models are 230 volt 50 hz for European use.  I found one that said it did 50 or 60 Hz, but it said it is only sold OUTSIDE the USA.

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.  Like Brian said, Magnum makes a stackable inverter that will do 240 volt.  Outback does too and probably Xantrex.  (Not sure on Xantrex as they don't make that many RV inverters anymore.)

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.

[Sean]

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).

Brassman
  They make inverters that produce/use 240 volts
http://www.tripplite.com/en/products/product-series.cfm?txtSeriesID=818

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.

or ones that sync and stack like you are thinking about.
http://cgi.ebay.com/STACKABLE-POWER-INVERTER-2500-5000-W-24V-DC-240V-AC-/290534680285?pt=LH_DefaultDomain_0&hash=item43a53766dd

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.

...
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

[belfert]

If one is looking at a 220 volt inverter so everything in the bus runs through the inverter you can get 110 volt inverters with a 50 amp double throw transfer switch.  The RS3000 is one such model, but 12 volt only so it won't work for me.

[happycamperbrat]

WARNING: Hijack in progress!

I just want to make sure I got this straight, I have a 24 volt alternator and the 50-60 Vanner which gives me 12 volt for head lights and such. Now my understanding is

1) NOT to touch the batteries or Vanner in order to do a house/battery/inverter system,
2) I need a 24 volt inverter attached to my alternator and another set of batteries like this http://cgi.ebay.com/Magnum-4000-W-Inverter-24-V-105-Charger-more-/250774908231?pt=LH_DefaultDomain_0&hash=item3a63596d47
3) the inverter brands to use are Outback, Xantrex or Magnum (stay away from Chinese made ones)

Will most inverters work with 24 volt solar panels as well as wind power (small windmill when parked sometimes) as well as a big a$$ 24 volt alternator as well as a bunch of batteries wired together to make 24 volt power? 

I just want to make sure I am getting all this right...... Thanks!

[Sean]

WARNING: Hijack in progress!
...

I need to get on the road, so can't really take the time to answer right now.  But let me suggest that you should really re-post this as a new thread.  For one, this sort of hijack (your own admission) makes the current thread hard to read, and for another, I think you will get more interested responses by starting a fresh thread.

JMO, FWIW.

-Sean
http://OurOdyssey.BlogSpot.com

[Brassman]

Anyway, back to inverters, & in my thread hijack: those of the 240 volt kind.

My 240 loads would be a multi-zone mini-split heat pump, and induction hobs. I would want to run these off inverters, so if I only have a 30 amp RV power connection, I can still run them and a charger.

[belfert]

If my math is correct, you're going to have a hard time keeping a 220 volt air conditioner running during really hot periods if you're charging batteries through a 30 amp connection.  My assumption is that a 220 volt A/C unit takes 15 amps at 220 volts.  This essentially means it would take all of your 30 amp shore circuit to supply power to your inverter via a charger/transformer.  We have not even considered losses converting AC to DC and back again.

If the air conditioner isn't running continuously or it takes less than 15 amps this might work out.  Personally, I would do everything in my power to stay with 115 volt mini splits.

[Brassman]

12k 2 zone mini at about 8 amps on heat. I haven't sized up on the ac 'cause I'm too scared to look.

Belfert, I'll make a wager: that I can engineer my 240 V inverter bus electrical system to be, not only be more expensive, but also more complex and convoluted, than your 120 V mini-spilts system.

So far, it hasn't cost me a dime.

I'll wager a dime! 

[belfert]

I don't have any mini splits.  I meant to say if I was designing a system with mini splits for my use I would do everything I could do to use 120 volt mini splits.  I use roof tops primarily because I can't spare the bay space for mini splits or basement units.

8 amps isn't quite so bad, but remember you need to have a charger that would do a minimum of 80 amps at 24 volts to handle that load.  You would probably need 100 amps or more in reality due to conversion losses.

[Brassman]

I haven't figured out the duty-cycle on the ac's, so I don't know the amp-hours that I need to charge to.

At the moment, it's only a thought experiment; but I like the idea of a 240 V battery buffered circuit powering the non-resitive AC loads.

[Busted Knuckle]

OK not to "HIJACK" this thread..........But it was brought up so I'll ask.
I need a couple good quality 24 inverters say about 1000-1500 watts without all the fancy bells and whistles.
These will only be used while going down the road and there will be no "house battery system!"
They will be run off the existing 24 V coach batteries. No needs for charging the batts the alternator will keep things powered.

Any ideas ?
  BK 

[happycamperbrat]

My toys are packed and Im moving to my own thread lol....... my life of crime is over