Inverter Install Questions

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mylo

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Oct 1, 2012
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Phoenix, AZ
So, I have been considering a small inverter to power a small TV while boondocking. My small Class C has a 110v circuit that is dedicated for the outlets under the overhead compartments. In an effort to keep the DC wires short, I think I'll put the inverter near the converter/charger/fuse panel. I assume that the 110v circuits currently are fed directly from the output of the transfer switch. I suppose I could permanently rewire the circuit for the overhead outlets directly to the output of the inverter. Is there any drawbacks to this plan (besides the obvious overloading the inverter)? I was thinking that it might be advantageous to put in a contactor or relay that would automatically bypass the inverter when it sensed current from the transfer switch. When 110v power is not available, the relay would switch to power that circuit off the inverter. To me, this sounds like the best of both worlds.

Am I crazy?  ;D Ok, I know I am... but does this sound like it's worth the trouble?


Mylo
 
Those outlets will have a circuit breaker in your load center.  They will NOT be fed directly from the transfer switch.  If the inverter has a circuit breaker for the output, then you just need to move the wires from the circuit breaker to the inverter output.  I wouldn't get too complicated with any relays, as when you're on shore power, the charger will supply the 12VDC for the inverter input while charging the batteries.
 
A lot of inverters today have built in transfer switches.
Wire the  TV AC from the breaker to the AC input of the inverter and now the TV outlet will be always powered.

See this inverter..
http://www.xantrex.com/power-products/inverter-chargers/freedom-hf-newgen.aspx

Quote
Built-in 30-amp relay to automatically transfer between inverter power and incoming AC utility power
 
There are 2x2 types of invertes, 

First, True sine wave or MSW,, For your use (Television) True Sine is the better choice. MSW may or may not work well, but TSW will work.

The other type is "Stand alone" or Inline"  In line are often larger, and have built in chargers which you may not need.. 

Here is how you'd install an inline.

First; you install the inverter near the batteries, NOT in the same air space, but in a compartment nearby, keep the 12 volt leads to the Battery as short as possible.

now run a line from the existing breaker that feeds the TV to the inverter..  Likewise run a line back to a junction box you put behind or next to the breaker box for the power to the TV's (Or re-route that TV's power line, whichever is easier).

To do a stand alone:  Again, mounting is the same.

This time you replace the junction box with a automatic transfer switch.
Breaker to ATS, (Generator leades)  Inverter to ATS (Shore leads) load leads to Television.

Or you can use a manual switch,, (About 50 to 100 bucks)

or if the TV is small enough (many of the new LCD/LED jobs are) My new 19 inch pulls a great big whomping 25 watts) just run the thing off a TSW inverter full time and forget the transfer switch.  That's about 2 amps DC, perhaps 2.5 with overhead.  In fact that is low enough that if I had the traditional winegard outlet with the 12 volt accessory outlet and antenna connection.. i could powr it that way with a plug in inverter (They are good for only about 100 watts tops, this is 25 tops so ...)  Of course a larger one would draw more power.  Of course if  you have a Magnetek 6300, that might be a poor idea till you upgrade the converter.
 
A small inverter won't have a built-in transfer switch. For that matter, larger standalone inverters don't either. The transfer switch comes as part of an inverter/charger system and usually 1000 watts capacity or more.

I'm guessing you are thinking of a standalone inverter with a capacity of around 300-400 watts to power a tv. However, you need to move the entire branch circuit to the inverter if you want to use the existing outlets, and that circuit may have things in addition to the tv, so factor in their power needs as well. Alternatively, run a separate power cord to the tv from the inverter and leave the existing circuit alone.

For a relatively low power circuit such as you describe, there is little need to add in a relay to switch from inverter to shore power. Just let the circuit run off the inverter all the time.  Your house charging system will supply 12v top the inverter when shore power is available. That's the way the motorhome manufacturers handle similar situations.  There is a bit of efficiency loss that way, but for the amount of power consumed on that sort of circuit, a 10% loss is trivial in terms of total watts. However, if the circuit ends up being 1000+ watts and in use much of the time, then it becomes worthwhile to add in the transfer relay.
 
The link I made to the Xantrex Inverter are 1000w inverters. It has a built in transfer switch

The Inverter in our MoHo is a Magnum 600W
It has a built in transfer switch feeding front and rear entertainment centers and one dedicated plug.
Works just great for TV, DVD and Satelite, Charging lap tops

Here is the one from Magnum, a modified sine wave inverter
http://www.magnumenergy.com/Literature/Data%20Sheets/Inverters/64-0400%20Rev%20D%20(MM%20Series%20Data%20Sheet).pdf

Here is another one from Magnum, slighlty larger but a pure sine wave inverter
http://www.magnumenergy.com/Literature/Data%20Sheets/Inverters/64-0475%20Rev%20D%20(MMS%20Series%20Data%20Sheet).pdf


Today there is no need to mess around with external transfers switches.
These have been available for at least 5 years now.

 
Thanks for all the info, guys. Gary is the closest to describing my intentions. This is just my first, "starter" rig. I anticipate that we'll probably use it maybe 10-15 weekends this up coming year, and maybe one or two extended trips. If wires were easier to run, I would probably run a dedicated line to the tv, and run it off the inverter all the time. I haven't replaced the Magnetek 6300, yet. So, putting in anything that takes away from charging efficiency doesn't sound good.

If this works out, and we find ourselves bio docking as much as I think we will, then I will probably replace that charger, and get a second battery.


Mylo
 
The typical Magnetek 63xx of that vintage will be a 6330 (30 amp) or maybe 6340 (40 amp).  The 6330 can supply enough DC @ 13+ volts for about 400 watts. Subtract a few amps for lighting and circuit board consumption and you have about 350 watts available to operate the inverter. Plenty for a tv, if that's the only thing on that circuit. You won't have any extra for battery charging, but you probably don't run the tv all day & all night either, so the battery recovers during the off-peak periods.  I would probably add another battery (or a larger amp-hour capacity model) to help out during the peak load periods, though. And plan on replacing the converter portion of the 63xx in the near future. It's a really poor battery charger anyway.
 
Gary RV Roamer said:
The typical Magnetek 63xx of that vintage will be a 6330 (30 amp) or maybe 6340 (40 amp).  The 6330 can supply enough DC @ 13+ volts for about 400 watts. Subtract a few amps for lighting and circuit board consumption and you have about 350 watts available to operate the inverter. Plenty for a tv, if that's the only thing on that circuit. You won't have any extra for battery charging, but you probably don't run the tv all day & all night either, so the battery recovers during the off-peak periods.  I would probably add another battery (or a larger amp-hour capacity model) to help out during the peak load periods, though. And plan on replacing the converter portion of the 63xx in the near future. It's a really poor battery charger anyway.

Great advice. Thanks, Gary. I do have a 6345, and plan on replacing it with a PD4655 (and upgrading the wires between it and the battery to 4 ga. As I have mentioned before, I think there is a problem with my 6345 anyway.


Mylo
 
All the 63xx were a problem. Some are just bigger problems than others.  ;)  I've heard it said that they improve when they stop working - cause at least they aren't causing battery damage any more!
 
The typical Magnetek 63xx of that vintage will be a 6330 (30 amp) or maybe 6340 (40 amp).  The 6330 can supply enough DC @ 13+ volts for about 400 watts.

Just a minute, Gary.  The 63xx Series Magneteks are the ones that send unregulated, unfiltered power to the majority of the circuits and charge the batteries from a low current output.

The battery, which is where the inverter has to be connected so it's not running on unfiltered power, only has a 5-10 amp regulated charger.  That's 60-120 watts maximum for charging the battery and running the inverter.

Draw more than 50-100 watts from the inverter and the converter won't keep up - you can watch the battery drain whether you're plugged into electricity or not.

It's the 7300 series that can send it's entire output to the batteries.  Same for the Progressive Dynamics converters.  Either of these will let you run the inverter full time.  But don't try it with a 6300 converter.
 
Right you are, Lou, and I should have remembered that.  However, I don't see a major problem coupling the inverter to the main converter output either. Other 12v circuits seem to tolerate it ok, e.g. fridge & water heater circuit boards.
 
Ok. You guys lost me on the last two posts. It looks like some form of English you are using, but I still can't decipher it.  :p I doubt I will get an inverter before I upgrade the 6345. But when I do, I will be hooking it up to the PD4655. I'll be running some new 4 gauge wire to the house battery. I assume that I will be directly tapping off those leads to feed the inverter. I will not be powering the inverter from a spare circuit on the circuit board. The inverter should have it's own fuse, anyway, right?


Mylo
 
I was wondering how (other than my mention) of the 6300 it got so much space, I see you actually have one, this makes a difference.

Go with an inverter/converter large enough to have it's own transfer switch and charger stage (3-stage converter/charger stage) cut the 120 volt wire to the 6300 and be very very happy.

This way you get the built in transfer switch, you get a way better converter, (Which will pay for itself in extended battery life, that's life before replacement) and you can put the 6300 out of your misery.

The smallest "in-line' type you can find will run your Tv and electric razor. 1,000 MIGHT run a small microwave. 1500 will most likely do that, Mine is a 2,000 watt.
 
Hi Ho:  The question you have to ask is:  What do I want to do with the inverter?  That determines the size (in watts) which in turn determines the wire size etc.  Gary usually nails things right on, but this one time he missed on inverters with transfer switches.  WI put 300 watt inverters in a whole bunch of coaches that do have a transfer switch.  They also have undervoltage protection so that when the battery is too low it just shuts off.  They are, however, not cheap.  On our 2000 Iatasca Suncruiser we wanted to be able to watch TV (with the whole entertainment system--sat rcvr, autio amp. etc.).  So I simply put in a second 300 watt inverter just like the one from WI.  This was pretty simple because it takes just #10 AWG (American Wire Gauge)  wires which were there anyway.

If you have a friend that has electrical background that would be a good idea.  For example, the size of the inverter determines which wire size you need.  All wires should have a fuse to protect them.  Fuses protect wires, not devices.  So, it isn't a good idea to just hook a wire to the battery without a fuse/breaker of some type.  Without a fuse you have an arc welder in the making.

The simplest thing is just to plug a small inverter (without transfer switch) into an existing 12 volt outlet.  These little inverters are normally a couple of hundred watts and will power stuff like cell phones, computer, ipad etc.  They are so cheap you could consider them to be disposable.  And you could do this without running wires.  For us the real issue is running the TV system.  If you want to do this you will probably need a permanent (well, a wired) system of some type.

I hope this is of some help.  By the way, I have a MSEE and BSEE degree and lots of practical experience.  Well, most of it is pretty theoretical.    So I could use lots of words that you wouldn't know, but I don't think they are needed here.

Dirk
 
WI put 300 watt inverters in a whole bunch of coaches that do have a transfer switch.  They also have undervoltage protection so that when the battery is too low it just shuts off.  They are, however, not cheap.  On our 2000 Iatasca Suncruiser we wanted to be able to watch TV (with the whole entertainment system--sat rcvr, autio amp. etc.).  So I simply put in a second 300 watt inverter just like the one from WI.  This was pretty simple because it takes just #10 AWG (American Wire Gauge)  wires which were there anyway.

Dirko,
If the inverter only has a 12v feed, then it does NOT have an internal transfer switch. The only reason to have a transfer switch in an inverter is to shift between external 120v power and inverted 120v, and that requires a 120v feeder to the inverter.

Your Winnie may be different, but the typical small inverter installation for the entertainment system simply runs the inverter 24/7, whether on shore power or battery. No power switching - they rely on the converter/charger to keep up with the 12v demand when plugged to shore power. Works fine.
 
ok I read these posts, and I still have a question.

background...I have a 2000 Rexhall 36BSL with 30 amp A/C power supply, and a 5.5k generator, good house batteries and a 1500 watt solar charger.

I also have a Xpower 3000 plus (remote on switch) watt inverter that I have used before when the shore power went out and it works great. what I did was plug an adapter into one of the 15 amp A/C plugs into my 30 amp power cord. 

so I got the bright idea to hard wire it into the A/C input wire so when the power goes out I can just hit the remote switch and continue watching the History Channel with out having to go outside and change the power cord around.

But when I reset the 30 amp shore power breaker it tripped instantly, even with the inverter turned off,

On this M/H there is a factory switching relay that senses generator power and overrides the shore power, so I put the A/C output wires on the same leads that the generator power comes in on hoping that when the power goes out I can hit the remote inverter switch and continue on with silent A/C.

I haven't tested it because I don't want to, as they say...Let the smoke out of the inverter...or blow it up.

But...I got to thinking..what will happen when I fire up the generator ? will it trip the output breakers on it ?

Will I need to put another input isolator  switching relay  in the system?
 
I hope you disconnected the generator wires and replaced them with wires going from the inverter to the transfer switch.  If you left the generator connected, it's a dead short across the inverter.  Same thing holds true when you start the generator - the inverter will look like a dead short to it.

That's why the shore power breaker tripped when you connected the inverter across it.  You can only have one AC source connected at a time.  That's what the transfer switch does - it disconnects shore power when the generator is running, and the generator when shore power is on.

To do what you want, you'll need a second transfer switch to select between the generator and inverter.

And test your inverter by plugging something into it.  I'm sorry to Saturday there's a good chance the shore power fried it when you applied shore power to it's output and tripped the 30 amp breaker.
 
that's what I thought,
but why does it trip when the inverter is in the off position, there is no incoming A/C power then?
 
The on/off switch just controls whether the inverter is making power or not.  The inverter is still a dead short to outside power no matter if it's on or off.    Same for the generator - it's still connected even if it's off.

That's why you need transfer switches.  They connect the load to one and only one source of power at a time.
 

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