Second Transfer Switch Needed To Add Inverter?

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Second Transfer Switch Needed To Add Inverter?

February 27, 2018, 10:45:16 am

Hello All you wonderful foretravel peeps!

I just found a gently used GoPower 2000 watt pure sine inverter for a steal of a price and am considering buying it and adding it to my electrical system so my outlets have power from battery bank when not plugged in to shore.

My current setup includes a converter charger unit that charges batteries definitely from shore power, haven't checked if it's hooked up to genset (but I imagine it is). A 50amp transfer switch that switches from shore to genset. It's set to be normally closed on shore power side and trips to genset side when that side is energized for 30 seconds or more.

Shore and gen are wired directly to transfer switch. Switch output goes to electrical panel. Pretty sure charger goes from panel to batteries (I'll double check and confirm).

My question is: do I need a second transfer switch?

Ideally, the system would order as follows:
1 - shore power when available, if not
2 - generator when available, if not
3 - inverter power, if not
4 - no ac power so we shed a tear and wallow in sadness.

Currently our system skips step 3 and goes right to 4. lol.

I had been planning on buying GoPower's 2000watt inverter, charger, switch combo and installing that (which would replace existing charger... I think... but not the existing transfer switch which is still needed... I think)

But this one came up and for the price... I could buy it and 10 more transfer switches before I hit the price of the combo unit. If I can figure out what I need (and, the clincher, have the space for it), then I'm all up for saving money and using this unit... even if the install is slightly more complex.

Thanks in advance!

Re: Second Transfer Switch Needed To Add Inverter?

Reply #1 – February 27, 2018, 11:14:13 am

Transfer switches won't solve the problems you will have if the inverter just has the 2 ac outlets for your ac power. There is no ac power input on the inverter just dc. Maybe one of the experts can better explain it. It can be done with some manual ac a/b type switches, but complicated.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #2 – February 27, 2018, 11:29:31 am

Quote from: AKATheAlchemist – February 27, 2018, 10:45:16 am

Hello All you wonderful foretravel peeps!

I just found a gently used GoPower 2000 watt pure sine inverter for a steal of a price and am considering buying it and adding it to my electrical system so my outlets have power from battery bank when not plugged in to shore.

My current setup includes a converter charger unit that charges batteries definitely from shore power, haven't checked if it's hooked up to genset (but I imagine it is). A 50amp transfer switch that switches from shore to genset. It's set to be normally closed on shore power side and trips to genset side when that side is energized for 30 seconds or more.

Shore and gen are wired directly to transfer switch. Switch output goes to electrical panel. Pretty sure charger goes from panel to batteries (I'll double check and confirm).

My question is: do I need a second transfer switch?

Ideally, the system would order as follows:
1 - shore power when available, if not
2 - generator when available, if not
3 - inverter power, if not
4 - no ac power so we shed a tear and wallow in sadness.

Currently our system skips step 3 and goes right to 4. lol.

I had been planning on buying GoPower's 2000watt inverter, charger, switch combo and installing that (which would replace existing charger... I think... but not the existing transfer switch which is still needed... I think)

But this one came up and for the price... I could buy it and 10 more transfer switches before I hit the price of the combo unit. If I can figure out what I need (and, the clincher, have the space for it), then I'm all up for saving money and using this unit... even if the install is slightly more complex.

Thanks in advance!

If you coach did not come with inverter, you are looking at a big project. Your existing panel probably has breakers for heaters and air conditioners so can't be run from inverter. Best bet is to make dedicated circuits wired only to inverter and not try to combine with your other systems.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #3 – February 27, 2018, 11:38:48 am

I am still installing this setup, but I thought I should share what I am doing as a perspective. This has turned into a pretty big project. It is still being put together and of course subject to change.

My '91 U280 was stock, with the original battery boiler power converter/charger and the 1500 Watt modified sine wave inverter. I have purchased but not installed a Xantrex Freedom Xc 2000 Watt inverter/charger with built in 30 Amp transfer switch. So far I have pulled out the old converter and inverter and started the wiring. The plan is to replace the existing 120 VAC electrical panel with a pair of smaller 6 breaker panels, one configured as a main. The existing power feed into the panel from the existing shore power/generator transfer switch will be fed to the new main panel. The new panel will feed the 2 roof A/C units, the air compressor, block heater, and a 30 Amp feed to the new inverter/charger. The AC output from the inverter/charger will feed the new sub panel with all the existing circuits to the microwave, refrigerator, outlets, trash compactor, and so forth moved to it. The plan it to replace the refrigerator with a small residential unit. The existing down stream microwave/outlet switch from the inverter and its wiring will be removed. This will allow all AC loads on the sub panel to be powered from the inverter. I was able to find 2 small panels that are almost the same size as the existing panel. If I can get this all together, then all the outlets and most of the smaller built in AC loads can be operated independent of the shore and generator power. I have all the parts except the refer, I am just dealing with installing the wiring.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #4 – February 27, 2018, 12:33:24 pm

Our U280 originally had a inverter, and a separate convertor/charger. These have both been replaced with a single combo inverter/charger. The link below is to a diagram of our original factory wiring setup, which used 2 ATS boxes. It may be of some help in showing one example of how the factory accomplished what you are trying to do.

http://www.foreforums.com/index.php?action=media;sa=item;in=3267#viewitem

Re: Second Transfer Switch Needed To Add Inverter?

Reply #5 – February 27, 2018, 01:03:23 pm

@Chuck - Thank you that's really useful.

@jcus - I'm a tad confused on this... why can't the the AC output from the inverter go directly to the main breaker panel? The shore power and the generator put out ac power and go directly into that box.

Is it because the AC/Microwave draw more wattage than the inverter can safely supply? because if that's the case... we have no microwave and the AC units have a fan mode that I'd like to be able to use with the inverter... would it work if we just didn't turn on the compressor when on inverter power?

@rvtinker - Thanks for the ideas. I'd like to not rebuild the breaker panels if possible. Though I can see the benefit of having the outlet be able to run from the inverter separately. Does this make it so they are always drawing from the inverter or will the inverter panel to pulling from shore power when available?

Thanks everyone!

Re: Second Transfer Switch Needed To Add Inverter?

Reply #6 – February 27, 2018, 01:20:08 pm

@rvtinker - Thanks for the ideas. I'd like to not rebuild the breaker panels if possible. Though I can see the benefit of having the outlet be able to run from the inverter separately. Does this make it so they are always drawing from the inverter or will the inverter panel to pulling from shore power when available?
[/quote]

Power always go through the inverter, but since it has a built in transfer switch when it is on shore power or generator the power just passes right through and the inverter is actually off. Instead it runs as a charger, pushing back to the batteries.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #7 – February 27, 2018, 02:01:21 pm

@rvtinker - Yeah, I was considering getting the inverter/charger/transfer switch combo. But the one I want from Go Power is $1500. Hence my question... because I can pick up this 2000kw inverter and pickup a three leg transfer switch like this one: Amazon.com : Esco ES350 Automatic Transfer Switch for 350A Power Sources... for $550... and still be half of the cost of the inverter/charger/transfer combo.

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #8 – February 27, 2018, 02:02:08 pm

Quote from: AKATheAlchemist – February 27, 2018, 10:45:16 am

I had been planning on buying GoPower's 2000watt inverter, charger, switch combo and installing that (which would replace existing charger... I think... but not the existing transfer switch which is still needed... I think)

Alchemist,

What you are describing above (GoPower 2000) and what rvtinker is talking about is exactly the setup we now have in our coach. In our case it is a Magnum MS2812, but the brand is not really important. The selling point of a well designed combination unit is that it can simplify your life. The inverter/charger will send whatever 110V AC power it receives straight through to the coach, and at the same time automatically switch between charging the batteries (when AC power is available) and pulling 12V power out of them to convert to 110V (when AC power is not available). Once that function is covered, then the only choice that remains is: what is the source of the AC power - shore line or generator. If you want that choice to be automatic, then you still need one ATS. Or you can do like we did, and replace the remaining ATS with a manual switch.

Running the fan in a roof air unit on inverter power is no problem, as long as the inverter (and your battery bank) can handle the load. Our coach is (now) wired with the front roof A/C on a circuit that is supplied by the inverter. We occasionally use the fan mode to circulate air (when running on inverter), but because of the increased noise level, we really prefer to use (one or two) small table model fans instead.

Our coach does have two 110V panels (main and inverter), which sounds similar to what rvtinker is describing. That 3-way transfer switch looks pretty cool. I'm not a electrician, so most of this stuff is above my pay grade. I don't know what setup would work best for upgrading your coach. Smarter members than me will, I am sure, present you with different options.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #9 – February 27, 2018, 02:17:42 pm

If you are careful not turn on any high amperage appliances, you can use the transfer switch you mentioned, but plenty cheaper than that. PowerMax PMTS-50 AMP 120 240 VAC RV GENERATOR AUTOMATIC TRANSFER SWITCH | eBay
I had a old coach that came without an inverter. I installed an inverter and just plugged the shore power cable into it when I was dry camping and did not want to run generator.
RV Trailer Parallax PWR 50amp to 20amp Plug - Cesmad5020 Power Cord Adapter...

Re: Second Transfer Switch Needed To Add Inverter?

Reply #10 – February 27, 2018, 02:44:07 pm

Alchemist,

FWIW I paid less the $600 for the new Xantrex Freedom Xc, an inverter, charger, and transfer switch all in one. It switches over in 20 milliseconds so it can actually function as a UPS for computers. I did pay $50 more for a remote panel so I could mount it down in the bay.

Really, just installing an inverter then connecting it to an outlet to plug the shore power cord into it the easiest solution. I was planning on doing this on my old Class B+ SOB, but never got a round to it. Of course, you would have to remember to shut off the charger though.

Another solution is just install a couple of surface outlets and wire them to the inverter. Some folks just use multiple small inverters.
You can make it as simple or complicated as you want.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #11 – February 27, 2018, 07:52:40 pm

As your 280 has two house batteries the 80 amp charge should be fine.

30 amp pass through.

Manual battery temp setting.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #12 – February 27, 2018, 09:58:47 pm

Hank you guys for all the incredibly useful feedback!

I went ahead and got the used inverter. And some 0 gauge automotive power wire to run. I think I'm gonna go with the "plug the shore power in" method to keep the install simple.

Just gotta figure out how to turn off the charger. I'll have to look and see if it's got an on/off switch or a breaker somewhere in the line.

Also means I'm gonna have to add a switch to my electric water heater rod. So I'm not running that off of the inverter. I assume that'd be a battery killer.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #13 – February 27, 2018, 10:09:00 pm

Any recommendations on a battery monitor that will tell me the amperage draw on the system from the 12v and inverter systems?

The built in foretravel battery monitor just has 10 steps of battery level. Not very detailed.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #14 – February 27, 2018, 10:18:43 pm

Quote from: AKATheAlchemist – February 27, 2018, 10:09:00 pm

Any recommendations on a battery monitor that will tell me the amperage draw on the system from the 12v and inverter systems?

The built in foretravel battery monitor just has 10 steps of battery level. Not very detailed.

TriMetric Model Descriptions - Bogart Engineering

Re: Second Transfer Switch Needed To Add Inverter?

Reply #15 – February 27, 2018, 10:20:22 pm

Many of us use the Victron BMV-702. House and start batteries. Or House and house battery temps. Bluetooth capable.

Victron BMV-702 Battery Monitor

https://baymarinesupply.com/media/catalog/product/documents/victron/BMV-700-700h-702-Manual.pdf

Lots of other choices out there too.

Roger

Re: Second Transfer Switch Needed To Add Inverter?

Reply #16 – February 28, 2018, 08:19:12 am

For battery monitoring I used a TriMetric 2030RV in the old RV and it worked great. I have a Xantrex LinkPro waiting to go into the GV. I used the older Cruising Equipment/Xantrex Link10s in my EVs for years and kind of like the flexibility, alarms, and so forth. We will have to see how LinkPro works out. It would have been nice to the Bluetooth though.

BTW Alchemist, what kind of coach battery pack do you have? A big inverter can burn through a lot of charge in a hurry, and large loads can cause enough voltage sag to shut the inverter off. I am feeling reasonably comfortable my pair of 8D AGMs will be stiff enough, but I still intend to be conservative with the loads. I suspect flooded batteries would sag much more even at the same state of charge.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #17 – February 28, 2018, 08:42:53 am

Quote from: rvtinker – February 28, 2018, 08:19:12 am

A big inverter can burn through a lot of charge in a hurry, and large loads can cause enough voltage sag to shut the inverter off. I am feeling reasonably comfortable my pair of 8D AGMs will be stiff enough, but I still intend to be conservative with the loads.

We have found our two 8DAGMs are just barely sufficient when dry camping. We have a residential fridge, and so our MS2812 inverter is running 24/7. One situation we constantly encounter is wanting to use the microwave first thing in the morning. The battery bank is already depleted from the over night draw, and the sun isn't up yet so our solar panels aren't working. Trying to use the microwave in that situation will sometimes knock the inverter off line. The only solution we've found is to run the generator...or do without the microwave. I think adding one more 8D battery would definitely improve our setup. Just need to find a place to mount it...

Re: Second Transfer Switch Needed To Add Inverter?

Reply #18 – February 28, 2018, 09:55:23 am

Quote from: Chuck & Jeannie – February 28, 2018, 08:42:53 am

We have found our two 8DAGMs are just barely sufficient when dry camping. <SNIP> I think one more battery would definitely help our setup. Just need to find a place to mount it...

I have been wondering about switching the engine starting duties to 2 or 3 group 31s in parallel and adding the existing 8D engine battery to the coach set. With the move of the battery isolator from behind the left rear wheels, that space would become available. I seem to recall someone else doing something similar.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #19 – February 28, 2018, 10:22:46 am

The batteries need to be the same size, age and condition. Having 3 8D's is great if they are all purchased together.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #20 – February 28, 2018, 10:33:31 am

Quote from: AKATheAlchemist – February 27, 2018, 09:58:47 pm

I went ahead and got the used inverter. And some 0 gauge automotive power wire to run.

Don't mix battery types, sizes and ages.

I assume you are using 1/0 wire. If the run from the batteries to the inverter is less than 10 ft than this is the minimum sized wire for the size inverter to minimize voltage drop. It likely has some short term capacity higher than 2000 watts and about 10% efficiency losses so at max possibe loads it is probably small. Many of the older coaches were wired with 2/0 wire. I replace one last summer with a 2800 watt inverter/charger and we used the 2 2/0 cables for the negative side and a new 4/0 cable for the plus side.

You should be putting in a 250 amp fuse near the battery and probably a switch too. BlueSea makes quality switches and fuse holders.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #21 – February 28, 2018, 10:42:44 am

Quote from: craneman – February 28, 2018, 10:22:46 am

The batteries need to be the same size, age and condition. Having 3 8D's is great if they are all purchased together.

No, you definitely would not want to mix and match. That is kind of why I am looking at that now. Mine are all identical and purchased together in December.

On the wire size, my existing inverter was wired with 3/0 by Foretravel. I am just reusing the existing cables.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #22 – February 28, 2018, 10:52:40 am

Thanks for the monitor recommendations. I'll check them out.

Our batteries are 6 volt lifeline's. I have two of them making a 12v System. 200 amp hours. They seem to last forever running our 12 volt system. All we ever use is lights, propane furnace, and occasionally my portable inverter for the entertainment system.

The new built in inverter I purchased will be used for the same thing basically. Just making the outlets work so we can charge computers/phone. Required for work and school... so hopefully we can continue doing that while boondocking.... which we have yet to try cause we didn't have power figured out. But with our generator working now and the new inverter... we should be god to try.

We don't use the microwave. And the fridge can run on gas. So only addinal load on batteries from the inverter should phone/computer charging and occasional fan use.

Also... I didn't know about the age mixing of batteries? Are ya'll saying I can buy two more of my 6volt Lifelines? I spaced the purchase cause those babies are super pricey. They are only a couple months old. Barely used cause we have been plugged in 100% of the time, except for the occasional drive from one site to another.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #23 – February 28, 2018, 01:25:26 pm

My battery distributor has suggested that ages within months are OK. Once you get to a year or more then age starts to make a difference especially when wiring from battery to battery because internal resistance changes over time. All batteries with equal length cables to a common bus bar may be more tolerant of an age difference. It is the best way to wire them in any case.

Re: Second Transfer Switch Needed To Add Inverter?

Reply #24 – February 28, 2018, 04:18:43 pm

I think adding one more 8D battery would definitely improve our setup. Just need to find a place to mount it...

Chuck are your batteries mounted in the same tray as the engine start? I had good results in OREDS with making the step well batteries all house and installing a different 8d for engine start in the engine compartment itself?

Not sure how yours is wired.....

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