Inverter hookup question

[Rhythmtone]

Hi again,
My build is going fairly well,
I went with the Victron Multiplus 12/800/35 - it's bigger than I need, physically and electrically, should have maybe gone with the 12/500/20, but too late - everything is already sized for it, and I wanted a charger closer to the original amperage of 45A. And in theory, it won't hurt to have more capacity - It's currently installed as a charger, next to the LVD, working great. Wire run to/from battery is currently 15ft of 4AWG, but I will cut it down to about 7ft soon - Victron manual states 4AWG is good for 5m, and that's what the unit is sized for (the connectors).

My question is - when connecting the inverter side (AC output) back to the house panel, can the neutral and ground go to the same bus bars (in the brown box) as everything else? And then hot (black) would ONLY go to the breaker serving the outlets - the other breakers (AC, microwave, and charger input) would remain directly wired to shore / genset as built - the charger breaker is already connected to the new Victron obviously.

This way only the outlets are connected to the inverter, although always connected, and the unit has pass-thru, etc.

I don't see why this would be a problem but I wanted to run it by people with more knowledge.

Thanks,
Dave

[Rhythmtone]

No reply but I figured this out.

I had to run the hot (black) wire that feeds the outlets to a separate AC breaker - single pole type, with input (inverter) and output (outlets) terminals - it can't be part of the main panel because then the inverter was feeding everything, including microwave, heat pump, outlets, and itself (in a loop) - it does share the neutral (white) and ground (green) bus bar connections with everything else, just hot (black) wire had to be isolated on its own breaker, mounted close by, but separate.

I'm glad I got the bigger unit (Multiplus 12/800/35), even though it was more difficult to install, because now I can run the fridge from the inverter on AC (and/or it won't be a problem if someone does this accidentally), along with plenty more things, if necessary. Would be nice if the fridge had a dedicated AC circuit, but oh well - maybe if I see the need in the future.

To add, the Multiplus also has a trickle charger connection for the starter battery, I re-used the old amplifier wiring that was in the AV cabinet, which was a sweet bonus! Very happy with the unit overall with this and with its features!

Maybe someone will read this and it will help them in the future,
Dave

[Blue~Go]

I'm glad I got the bigger unit (Multiplus 12/800/35), even though it was more difficult to install, because now I can run the fridge from the inverter on AC (and/or it won't be a problem if someone does this accidentally), along with plenty more things, if necessary. Would be nice if the fridge had a dedicated AC circuit, but oh well - maybe if I see the need in the future.

The pass-through feature is nice (presuming that's what you are describing). I think that eliminates the need for an inverter sub-panel (tho this is not my area of expertise).

On the fridge: Doesn't it default to AC (within its own self) if it detects AC at the outlet it's plugged into? That's how my compressor fridge works anyway. In other words, the refrigerator control box decides on its own to switch over to AC anytime it's present at the outlet the fridge is plugged into -- and it won't run on DC if that's the case.

To add, the Multiplus also has a trickle charger connection for the starter battery, I re-used the old amplifier wiring that was in the AV cabinet, which was a sweet bonus! Very happy with the unit overall with this and with its features!

I thought that sounded pretty nifty, but then I saw all the "here's how this thing really works" threads on the Victron forum. So I'm curious if it's just straightforwardly working for you? (The trickle charging.)

[BobW9]

A couple things to think about, which I found out only after installing my inverter (Victron 12/3000/120):

1) Note the stupid inverter only passes through power when it is turned on. It can be in regular mode when the charger and inverter are both on. Or it can be in charger-only mode where the inverter is not on. But the inverter itself must be on to pass power.
I found this very annoying when I first had the inverter off and had no AC, even though I was hooked up to shore. This means if the inverter breaks, or you're working on the batteries or DC wiring and need the inverter off for safety, you have no AC outlets anymore, unless you bypass the inverter entirely.

2) AC vs Propane: You may not have this problem if you don't always have the inverter on like I do (I have it supporting most of the distribution panel, AC outlets, microwave), but when hooked up somewhere with it on, if the power goes off, the fridge is on AC and will run down the batteries at a fair clip. If you're inside and awake and notice it, you can turn the inverter to charger-only mode. Or in my case, after an hour or two, if power isn't back on, I would go outside and unplug the fridge from AC, to force it to switch to propane.

3) If you're using the AC outlets for anything more than a few small USB devices or something, I'd suggest turning the inverter to charger-only mode so nothing happens if there is an outage and the inverter tries to kick in with too much current being used.

Or maybe you're planning on only having the inverter on while you're driving, to power the fridge, and in charger-only mode the rest of the time?

But is it okay to have significantly more power going through the inverter than it's rated for, even when it's in charger-only? Like if you have a toaster running (and fridge), you'd be up to 10-14 amps probably.

You have Power-Assist when the inverter is on, so it can boost the shore power, but I don't know what happens when it has a max assumed to be coming in from shore of 700 Watts? Does it say, cool, no problem, shore is giving me 1400 Watts, I'll just pass that along? My 12/3000 has limits set in the software and I don't think I can go higher than 30 amps expected coming in - at which point it will boost if I have the inverter on and the Power Assist turned on. I can set the incoming amps lower than 30, to tell it I've got a shore that only supplies say 20 amps. But the reverse, I'm thinking isn't allowed. Let us know.

4) I have my inverter on all the time, not least because some places I've been in New Mexico the power stations have a bit of a voltage drop once in a while when switching substations or something. Usually its only down to 110V or even 105V, but if it drops a bit further, even for a second, my computers can have problems (I'm a programmer but don't like laptops much).

I've also noticed my whole-house surge suppressor, an EMS-HW30C, sometimes triggers (cuts off power to protect things) on a short Voltage drop that might not have been enough to cause AC outlet/computer issues if I weren't using it, but since I am, it is enough to force the inverter on for a few seconds to keep everything running.

5) I am full time in my Concourse, and in the winter months I tend to be in state parks or places that have shore power (cheaper than running propane), and use a ceramic heater, or even 2 when temps drop to 10F or even 5F at night. I was using the AC outlets (or one in the AC outlet and a second using the Microwave outlet in the cabinet), but then my inverter has to power them if there are issues, especially at night with those low voltage drops. So I finally added a 20 amp AC outlet in my outside compartment next to the 30 amp AC outlet, and have a new outlet inside for the heaters to run off that separate 20 amp shore connection (most places I've been, if they have a 30 amp, they also have a 20 amp next to it). Turned out kind of nice, as it also means I don't have to worry about the heater(s) running when using the microwave, and my computers on, etc, which can occasionally go over 30 amps total for a few minutes.

I would have noted these concerns earlier on this thread, but I haven't been paying much attention to the forum for a while.

Bob

[Rhythmtone]

Thank you for the replies! I have also been busy and not checking in here, so please excuse my slow reply - I also wanted to spend some time with the system, etc.

My fridge (new RecPro) can be manually forced to use any power source, but there is an auto mode as well. You made a good point about shore power failing, as it won't know to switch to propane, because the inverter will take over - this is where a dedicated AC circuit for the fridge would be nice, I'll have to think more about that.

I have the BMV-712 that can alert me at 50% SOC, and there are also low-voltage and low-SOC settings that will cut off the inverter, and then the fridge will auto-switch to propane, so that's another option.

However my usage case is the opposite of Bob’s - unless forgotten, which does happen, I will always have the unit in charge-only mode when I have shore power - off when driving (alternator charge for fridge in DC mode), and the inverter will only be on to watch TV and charge laptops when dry camping, these things mitigate the problem even more.

I'll have to get back to you on the engine battery trickle charger, it certainly seems to be working fine - although another option for me is that I switched the battery boost to a toggle switch, and there will be some form of current sharing charging that way, charging all three batteries (sort of) with the main charger, so I will have to see - yes the motor battery is also AGM. The toggle switch just seemed easier and gave me more options to charge and move current back and forth between house and motor batteries.

For the pass-thru, I agree, it is annoying that it has to be “ON” in some form - a standby mode, where AC is still passed thru, would be really nice, maybe I'll ask Victron, haha. Related, yes it can pass through significantly more power than the inverter is rated for, mine is only 700W and I've run 1500 watts (space heater) just fine from AC power, just to exercise the genset. However there is a limit - the full name for my unit is 12/800/35-16 and the last number refers to the maximum AC amperage that it will accept, you cannot set it higher. Running with that much juice in pass-thru and the AC shuts off, I'm not sure what will happen, but I'm guessing the inverter will just use safety shut off.

Regarding heating, our roof unit has a heat strip, (I thought that they all did, but I guess not?) and we haven't been in less than 35 yet. But won't I be good below 0 with this? If so, no need to ever use a space heater from an AC outlet for our situation.

Hopefully I've touched on everything, I will post more as I learn more.

Thanks,
Dave

[BobW9]

I don't know about the RecPro, but most of the 3-way fridges are built the same - the DC mode has significantly less cooling than the propane and AC modes. With luck on a cool day, it might keep your food cool enough while you drive a few hours. But generally, if you start with the fridge section at say 35, it will go up a few degrees every hour or two, so after a long drive it is likely to be closer to 50F than 40F. If it is a hot day or in direct sun as you drive, it'll likely get warmer quicker. That is why I now drive with my inverter supplying AC for the fridge. I used to keep it on propane while driving, but that isn't the safest thing to do, so after installing the inverter, I stopped that. I keep a remote temp sensor in the fridge and the freezer all the time, so I can monitor things during the day or while driving. Even sitting at a campsite, I might have it at 3 at night and the morning if not in direct sun, then by noon up it to 4. On hot summer days if in direct sun in the afternoon, it needs 5 to keep the fridge under 40F. The freezer tends to do better, usually between 0-8F all the time.

According to the manual, the heat strip on the rooftop A/C is used down to 40F, then the controller would switch over to the furnace. I don't see where you've identified your vehicle, and you don't have a signature line with it, but I thought most Chinooks originally came with both A/C and furnace. If you have a Dometic, they state the heat pump (if you have a separate floor pump) shuts down at 24F no matter what, and I've heard the heat strip in the top unit shuts down sooner. And doesn't come back up until somewhere above freezing.

Having lived in my Concourse for the past few years, down to 5F at night, I see no way the heat strip would keep you warm enough even if it didn't shut down. Unless you don't mind the interior temps down into maybe the 30's at night (just a guess)? The colder it gets, the more the little open spaces in the walls and floor under the bathroom, or coming from the cab even after blocking it with heavy blackout curtains, let freezing streams in. Even after plugging everything I can reach, I can still feel some areas being colder than they should be if they were sealed from outside completely. I have multiple remote temp sensors in all sorts of places near water lines to monitor when it gets real cold (behind shower stall, in rear compartment with all the water lines there, in the front at the cab dividing line where the freshwater hot/cold lines have gravity drains).

Oh, and thick curtains for all windows are definitely needed if the temps are way down. My Concourse has the double-paned windows, and those are excellent (never any frost or anything). But the rims holding them in place get very cold, and cold air streams in through the little gaps in the railing bottom that must be open for rain water. Before my curtains, I used to lay down kleenex or napkins in that railing to block the air when super cold, but if you forget and get rain during a day above freezing, the water soaks the napkins and then overflows onto the walls (was not pretty, will never do that again!).

At the least, make certain to winterize your water lines, because the lines behind the bathroom and in the back will freeze for sure without some kind of space heater directing air under the sink and behind the stall (after removing the walls they have under the sink to hide the water and power lines). Unless your Chinook has much better foam insulation than mine - my Concourse has the winter package, but having opened virtually all spaces over the years, I found quite a few places where the foam insulation was less than an inch (they didn't do a very good or consistent job of spraying it on), and no heat normally reaches behind the stall (including if the propane heater is on). And then if not winterizing you need some heating pads under the RV on the tanks and those pipes (in particular, the drain trap under the shower - mine froze and cracked my first winter back in 2013).

Living in the Concourse full time in winters is a learning curve, and everyone's experiences will be different. Many go further south than me. I happen to like the central eastern area of NM, where you have lots of sun but still have winter. And the snow, when it comes, goes away in a few days after the sun is back out.

[Rhythmtone]

All great points, thanks,

1999 Premier,
I don't know if I have a floor pump, I don't think so, I think it's just the electrical strip in the roof unit, but certainly have a working propane furnace.

Being in California and not full-time I didn't worry too much about getting down to 5 degrees, but I do want to be prepared for next year's winter trips, as we intend to own the rig for a while, and explore.

Mine didn't come with a manual for the duotherm penguin I but I guess it's no good below 40? Sounds that way. That's when the propane heat would be fine I'm thinking, although an electric heater from the separate 20A plug is something that I'd like to explore. We also have very heavy and high quality wool blankets and sleeping bags - 30 in the cab isn't ideal, but 40-45 would be okay.

I'll think about the fridge, inverter while driving makes a lot of sense, but I've had good luck with even older fridges on DC with ice packs and a little fridge fans - won't be getting any colder probably, but can really keep it cool for a12 hour day of driving.

Space heater is no problem, and I do carry one, with a fan, just to save switching to propane when it's 20 degrees w/ shore power, but I've rarely needed it, and never experienced a shore power failure (yet) - but if we're boonocking, it's gonna be the propane furnace ATW.

I will advise further, although we're heading into the warm season, so if may not be for a while,
Thanks!