Inverter trouble and question

[michael.i@me.com]

Hey Guys, I have a question that I am hoping that someone here can shed some light on.

I have one of these http://www.xantrex.com/power-products/inverter-chargers/freedom-hf-newgen.aspx and it is installed in my RV. It works wonderfully and I have no complaints.

The problem arises when I have been out camping for a few days and I notice that my voltage is getting a little low. I figured that I would plug my inverters shore power connection into another inverter that I have mounted in my truck that is plenty big enough to handle the load on the Xantrex unit. Problem is, my Xantrex will Not switch to charging mode when I am using an inverter for shore power.

Now I did some looking online it it seems that modified sine wave inverters like the ones I am using dont provide 120v on the hot side like regualr shore power outlets do. From what I can gather, they have 60v on the hot side, and another 60v on the neutral line but out of phase from the hot side. So there is STILL 120v potential, but not 120 ont he hot side which I think the charger is looking for.

Does this sound right so far?

Ok, here is my question, If this is in fact the case, would it stand to reason that a 120v unit being 60 + -60=120v then a 220v Inverter would be 120v + -120v = 220v?

Could I use a 200 volt inverter and just take a line from the hot to ground to get 120v on a single line?

Does anyone have a 220v inverter that they could try this on?

In case anyone is wondering WHY I would want to use one inverter to charge another inverter, it is quite simple. Inverters are silent and this one has a great 3 step charger in it. It also will allow the loads in the camper to run from the shore power while charging, so I can just run this from my truck.


Next question, do Generators also behave like this 60v + -60v =120v?

I assume that inverter generators do, but what about normal generators? (non inverter type)

Thanks in advance, I appreciate any light anyone can share on this.


PS, I have tried several inverters and all are modified sine wave and all behave this way. Do PURE Sine wave inverters also function like this? would getting a Pure Sine Wave inverter do the trick?


Cheers, Michael

 

[ZOMGVTEK]

You need a sine wave inverter if you want to get the inverter to trip over to charge mode. Modified sine wave is just a nice way of saying horrible psuedo AC power. The inverter probably won't consider the 'shore' inverter power stable enough to toggle over to it.

A quality sine wave inverter should be about as close to grid power as you can get, and everything should work properly. The 220V inverter trick won't work.

 

[Alastor]

Or you can use a solid state relay for your loads in your RV and use your inverter anyhow you like
If you don't need to run motors or hard loads in your RV a sine wave inverter is quite to expensive in my opinion since there are other alternatives.