Understanding Electrical - Is my diagram correct?

[trekerboy]

I'm about ready to order parts to refit our old 1979 Airstream Excella's electrical system, but wanted to make sure I've comprehended the way things should be setup. I've never done this before, and have done a lot of learning, so I'm hoping y'all can confirm or help me fix the below diagram I put together:



Here are the items I'm considering for each component:

1. Power Converter: Boondocker 4 Stage Power Center 60 Amp (BPC4-60)
2. Power Inverter: SSW-2000-12A 2000 Watt Pure Sine Inverter with 4000 Watt Surge
3. Generator - Option 1: Powerhouse PH3100Ri Inverter Generator
4. Generator - Option 2: Amazon.com : Champion Power Equipment No.75531i Inverter Generator, 3100-watt : Patio, Lawn & Garden

Any feedback on those would be great. Also, I am in need of a recommendation for the following components:

1. Auto-transfer Power Relay. Used to auto-switch the camper's 120v power plugs to the Inverter when Shore Power isn't available.
2. Battery Isolator Relay. Used to effectively disconnect the camper's 12v battery bank from the tow vehicle's 12v (via the trailer wiring) when the tow-vehicle isn't on.

Thank you for your help!

[dbj216]

Hello trekerboy from Michigan. Welcome to Air Forums. I think this is the website that folks will chime in and answer your questions. I must say your plans are a bit beyond me.

I did install a Boondocker converter and have been happy with it so far. The 45 amp model I have does have a cooling fan that is a bit noisy, but I'm used to it now.

As you know, our trailers are 12v machines. The furnace, water pump, vent fans, fridge, water heater and lights are all 12v. Your converter or batteries power the trailer. Only the AC and the outlets are 115v AC. Do you plan on not using the 12v appliances in your Airstream?

Taking 12v to 115v AC through the inverter is something I've not done. Folks like to charge their phones and computers while boondocking, which is low power. Folks like to have a couple thousand watts or so of generator to power bigger 115v appliances like TVs and the AC. I wonder if you need the inverter at all if you plan on a generator for your 115v wants. You gotta be cognisant of your neighbors if you plan on running a generator close to them. Champions are rugged units, but not the quietest generator on the block. The inverter solves the problem for a little while but I think your batteries will drain pretty quickly.

Soon, other Airstream electrical folks will chime in.

David

[68 Overlander]

Your auto transfer switch is normally before the AC distribution panel so by the time AC power reaches the panel, it has sorted out the source, whether its grid, generator or inverter.
From your converter, it normally goes first through a DC distribution fuse board to power your DC accessories and from there on to the batteries for charging. It can route the other way but that would require a battery to always be installed to complete the circuit.

[trekerboy]

Originally Posted by 68 Overlander

Your auto transfer switch is normally before the AC distribution panel so by the time AC power reaches the panel, it has sorted out the source, whether its grid, generator or inverter.
From your converter, it normally goes first through a DC distribution fuse board to power your DC accessories and from there on to the batteries for charging. It can route the other way but that would require a battery to always be installed to complete the circuit.

Thanks for the advice Randy, one question... If I situate the auto transfer relay between the shore power receptacle and the AC Breaker Panel, wouldn't that mean that both my Power Converter and Air Conditioner would try to run when the power inverter is supplying power (via the auto-transfer switch)? I was trying to design the system to avoid that situation... Is there something I'm missing?

[DaveFL]

Originally Posted by trekerboy

Thanks for the advice Randy, one question... If I situate the auto transfer relay between the shore power receptacle and the AC Breaker Panel, wouldn't that mean that both my Power Converter and Air Conditioner would try to run when the power inverter is supplying power (via the auto-transfer switch)? I was trying to design the system to avoid that situation... Is there something I'm missing?

Usually inverter only powers a couple of receptacles by not running it into the breaker box, it would get it's power supply from a receptacle connected to the breaker. Auto transfer wouldn't have input from inverter just the gen and shore..

[trekerboy]

Thank you for the advice everyone.

Along with Randy we decided it would be best for me to connect the Power Inverter in such a way that it would power the everything coming off the 120v electrical panel and I should just remember not to run the Air Conditioner when the Power Inverter is on to avoid overloading it.

My question is now: how should I wire the system so that the Power Converter (Battery Charger) is NOT running when the Inverter is powering the camper?

My worry is that if I have the Inverter getting power from the 12v batteries and powering the whole 120v electrical panel, and the Converter is getting power from the 120v electrical panel and charging the 12v batteries, I'd have a circular setup with the inverter trying to charge the batteries from it's drawing power!

Do I need to have two separate 120v panels from shore power, one JUST for the Converter (which the Inverter would NOT be connected to) and another for the rest of the camper (with auto-transfer switch wired to Inverter)?

If anyone has advice on how to setup a Power Converter (battery charger) in combination with a Power Inverter that powers you're whole camper when not connected to shore power, I'd love to hear from you!

Attached is an image of my current blueprint, RED shows where I see the problem.

[DaveFL]

Simplest is move one red arrow from power inverter to auto transfer power relay add another blue box put a red arrow to it and label the box inverter controlled outlets, then add those outlets that will only work with inverter.

[toastie]

Found this diagram to be very helpful

toastie

[trekerboy]

Originally Posted by trekerboy

Thank you for the advice everyone.

Along with Randy we decided it would be best for me to connect the Power Inverter in such a way that it would power the everything coming off the 120v electrical panel and I should just remember not to run the Air Conditioner when the Power Inverter is on to avoid overloading it.

My question is now: how should I wire the system so that the Power Converter (Battery Charger) is NOT running when the Inverter is powering the camper?

My worry is that if I have the Inverter getting power from the 12v batteries and powering the whole 120v electrical panel, and the Converter is getting power from the 120v electrical panel and charging the 12v batteries, I'd have a circular setup with the inverter trying to charge the batteries from it's drawing power!

Do I need to have two separate 120v panels from shore power, one JUST for the Converter (which the Inverter would NOT be connected to) and another for the rest of the camper (with auto-transfer switch wired to Inverter)?

If anyone has advice on how to setup a Power Converter (battery charger) in combination with a Power Inverter that powers you're whole camper when not connected to shore power, I'd love to hear from you!

Attached is an image of my current blueprint, RED shows where I see the problem.

Attachment 228895

Ok, I think I figured out that if I don't want to have to manually turn off the Converter/Charger every time the Inverter is in use, I need to have a second 120v breaker panel that's use for the stuff I don't want the Inverter to power. I made a diagram (see attached). Would appreciate it if anyone with knowledge on this topic would tell me if there are any red flags with this system design.

[Wayward]

Originally Posted by trekerboy

Ok, I think I figured out that if I don't want to have to manually turn off the Converter/Charger every time the Inverter is in use, I need to have a second 120v breaker panel that's use for the stuff I don't want the Inverter to power. Attachment 228963

This is a good thread. Thanks for sharing your design.

The position of your transfer switch seems to solve the problem of isolating the inverter when connected to shore power. However, I am not sure why you want/need the second AC distribution panel. In your design, you will never been feeding it more than 15 amps AC, and I do not think it is providing any more overload protection than your design already has.

The inverter you have chosen puts out 12 amps AC and the spec sheet says it has built in overload protection. It is also is fuse-protected at the 12v distribution panel. That provides overload protection for your sub-circuit (your inverter-only outlet circuit) when running on batteries.

I assume your shore power feed for the transfer switch will come from a 15 amp breaker on the main panel. That gives you overload protection for your sub-circuit when running on shore power or generator.

I also assume the input and output wires to/from your transfer switch will be 14 gauge, feeding your sub-circuit. 14 gauge can carry up to 15 amps AC. Each outlet or appliance you wire to that sub-circuit will then have to wired to handle 15 amps. So, running each outlet in your sub-circuit off a 15 amp circuit breaker in a second AC distribution panel looks to be redundant and unnecessary.

I may have missed something, but hope that helps.

[Wayward]

You might want to consider an inverter with a built-in transfer switch something like this one. It can be hardwired to your AC distribution panel and also will charge lead-acid or gel batteries so the separate converter may not be needed.

Having one box instead of three might also reduce conversion loss.

That could simplify your design along with deletion of the second distribution panel per my previous comment. Just wire the AC output of this to the AC sub-circuit you want active when on battery power.

Owner Manual.

[DaveFL]

Originally Posted by trekerboy

Ok, I think I figured out that if I don't want to have to manually turn off the Converter/Charger every time the Inverter is in use, I need to have a second 120v breaker panel that's use for the stuff I don't want the Inverter to power. I made a diagram (see attached). Would appreciate it if anyone with knowledge on this topic would tell me if there are any red flags with this system design.
Attachment 228963

By this diagram you will have to choose power sources manually, the original auto switch relay between them and the panel, shouldn't be removed. I would trust two auto switches more than my memory to do the switching.

[lewster]

Your wiring is more complex than it should be. It can be simplified greatly by utilizing better components like a Magnum inverter/charger, which would eliminate the need for a converter and internal transfer switch.

ANY inverter should also be wired directly to your batteries and not thru your DC fuse block with the appropriate over current device and NEC specified cable gauge. You will need to size the inverter/charger for your anticipated AC loads if you plan to power your main breaker box with it. I typically don't use anything under 2000 watts for this purpose, with a minimum of 2/0 cabling and a 300 amp class 'T' fuse ONLY, depending on the length of the cable run from the batteries to the inverter.

You might also want to consider a 'hybrid' inverter like the Magnum MSH-3012M, which will allow you to include the A/C into your main breaker box, as it will supplement any low grade 120VAC input load up to the hybrid's 3000 watts, which will allow you to operate your roof A/C with a smaller single unit like a Honda or Yamaha 2000.

Your primary input breaker box is a good idea, as I also wire my whole-house inverter projects in this way, with the A/C included in this block (your panel 1). It should also have the inverter's 120VAC input power coming from there. The inverter's output is then routed into your main beaker panel.You also did not include a main input breaker in panel 1, or an inverter input breaker to panel 2.

You didn't state whether you were using 30 or 50 amp service, but the appropriate breakers must be used in either situation. A quality inverter/ charger Like a Magnum MS-2012 will handle either a 30 amp or 50 amp service, has a fully integrated internal transfer switch, a fully programmable 100 amp 4-stage charging section which is temperature compensated AND is fully field serviceable with a 3 year warranty. Made in USA also.

Choosing the right components will not only simplify your installation, but will also provide you with far longer service and better performance.

[trekerboy]

Originally Posted by lewster

Your wiring is more complex than it should be. It can be simplified greatly by utilizing better components like a Magnum inverter/charger, which would eliminate the need for a converter and internal transfer switch.

[...]

Choosing the right components will not only simplify your installation, but will also provide you with far longer service and better performance.

Thanks for you advice... after thinking about this, I think you're completely correct. I was trying to separate out components (converter, inverter, transfer switch) so that in the event of a failure I could just replace the thing that was broken (can't exactly JUST replace part of a combo unit).

I'll probably end up going with one of the two below options. Combining the Converter, Charger and Transfer Switch into a single unit will make this all a lot simpler, take up less space, and actually end up costing me less money.

These are the combo units I'm considering:

1. Tripp Lite 120V, 2000W PowerVerter APS Inverter/Charger with Pure Sine Wave Output
2. AIMS 2000 Watt Low Frequency Inverter Charger

I haven't heard many good things about the AIMS units, aside from the price, so I'll probably go with the Tripp Lite. Any Red Flags?

[lewster]

Definitely! Why do you insist on duplicating the charging system. Converters have no temperature compensation, and Airstream moved away from TrippLite to Magnum for the Interstates a couple of years ago.

If you intend to keep your batteries properly charged and simplify your installation considerably, them a Magnum is the only way to go.

Interstate owners have numerous complaints about the battery charging of the TrippLite, but it's your dime!


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357

[Del Gurney]

Been following this thread and must say the $$ diff. Magnum/Tripp-lite is substantial.

Just rebuilding an old AS and I'm really thinking about all-DC but for a couple laptop charging stations and maybe one AC plug inverted for re-charging devices like
razor, flash lights etc.

Just seems that a honda gen set answers a lot of power issues but I can only envision Air Conditioning and Micro wave as the problem here and I can see that to run either off the battery bank is going to cost some serious bucks. A good lap top can run any entertainment system through a moble-pre modem linked to the coaches stereo for any application.

Still this is a great thread, thanks

[lewster]

"Been following this thread and must say the $$ diff. Magnum/Tripp-lite is substantial."

There's also a substantial reason for the price difference.......it's called performance, quality and overall better operating characteristics. It's like using a Progressive Dynamics converter over a Parallax. Price difference.....yes. HUGE difference in performance............YES!

Like the old guy says........."Ya pays yer money and ya takes yer choice!).

[toastie]

Forgot to add diagram........toastie

[martin300662]

Originally Posted by lewster

Your wiring is more complex than it should be. It can be simplified greatly by utilizing better components like a Magnum inverter/charger, which would eliminate the need for a converter and internal transfer switch.

.......................

Choosing the right components will not only simplify your installation, but will also provide you with far longer service and better performance.

I am trying to do this with my rebuild. Admittedly it only has a 30amp service, our AC/heater is only 840w and we have no microwave (would rather use the space for a 600w toaster oven) so we have no individual item over 1000w.

But that means we have a single switch (between shore and generator), 110v runs through the Magnum, a single distribution panel with 110v and 12v sides, the ability to charge the batteries from solar (we have gone with a Zamp portable panel, but will consider a flex-panel install later), but also the batteries (using the Zamp connector) can be plugged into a Deltran battery tender when the entire system is shut down, rather than needing a 30amp shoreline.

[martin300662]

......actually I think this can be simplified even further. I am going to use a Eu2000i so if the 110v transfer switch is replaced with a single 30amp connector I can only ever plug in shore OR generator, so don't even need a transfer switch.