What size generator?

[Checkthisout]

It advertises it does. Will 'boost' from battery if the load sags the 'shore power' and then when it drops will go back to charging. I suspect it's internals are different for that. It's also as expensive as buying another generator though and I would still need an external solar charge controller as well from what I gather. I think it's more a limitation of the cheaper Chinese 'everything in the box' unit we mostly use.

Curious, how much was the EG4 you purchased?

 

[photomankc]

I'm guessing the generator has to be portable, confirm?
How many service hours should the generator last?
This one is made to last https://www.norwall.com/products/Cummins-Onan-QG-6-5-Propane-RV-Generator-6.5HGJAB-904/
Not so sure about this one https://www.norwall.com/products/Cu...el-Electric-Start-Portable-Generator-P9500df/

Do you need auto-start?

Portability is required for now as well as gasoline operation. My LP supply tanks are still 20# tanks mostly and they do not provide sufficient runtime for an LP generator.

Figure about 200hrs running per year. We tend to visit in Spring/Fall twice a month. Most stays are 3 days. Try to limit to 6hrs per day on generator. (This will change once panels are in)

Auto start would be great, but not required.

 

[photomankc]

Curious, how much was the EG4 you purchased?

$1250.00

 

[Checkthisout]

Also, 6500 watts is a buttload of juice.

$1250.00

Yikes ok. Just read up on it. That's a lot of juice for that little dough.

Do you need 6500 watts continuous and 13,500 surge?

 

[photomankc]

Not really. I do see eventually adding in a mini-split AC or heat-pump and a shallow well pump as well as some standard kitchen stuff (1000W Microwave, Air Fryer and instant kettle). So the surge can get up there worst case but average load on this will probably sit at 5-10%. Considered the smaller units but for the cost of a few tens of idle watts this seemed to provide more than I would need and clean wiring for installation.

 

[sunshine_eggo]

I thought the victron multiplus did exactly that?

Only in PowerAssist mode, and it won't charge then. I didn't want to complicate things. It effectively acts like a grid-tie inverter in that mode - it syncs to the incoming AC and then boosts it.

 

[sunshine_eggo]

Cool. I'm supposing the the electronics in the charger are making sure that they don't exceed that, which makes sense now that I think on it since they have to control the current to the batteries in the process of charging them. Thanks for confirming.

Not in the way you think. Something to tuck into your skull: A 15A/120V wall outlet can provide 1800W of power, but when you plug a 13W bulb into it, you only get 13W out of it.

The charger is doing this:
1) if below X volts, send 18A.
2) if at X volts, reduce amps to hold X volts.
3) if Amps < cut off (full charge), stop charging.
4) If volts is below Y volts (some lower safety limit), stop charging.

Your scenario as a water tank example: You have a very large water tank. You are draining 60gpm from the bottom of the tank. You are adding 40gpm to the top of the tank. The 60gpm drain has no influence on the 40gpm input... until the tank is empty, and the drain exceed the fill. At some point, the low water sensor cuts off the drain.

I was not clear on that prior but I got the picture after reading up more. That bypass was the mode it operated in while charging from utility just was not known to me before hand. As soon as I started it though and noticed it refused to charge while in BSU priority mode but in USB it did and stayed in bypass I knew my previous assumptions were probably in error. Makes sense if the pathway through the electronics is shared.

Think of it this way: Charging is AC to DC. Inverting is DC to AC. the same circuitry handles the conversion, it just depends on which direction things are going.

 

[Checkthisout]

Only in PowerAssist mode, and it won't charge then. I didn't want to complicate things. It effectively acts like a grid-tie inverter in that mode - it syncs to the incoming AC and then boosts it.

Well yeah if it's fully loading the Gen with the house load then it can't also charge the Batts the idea being you can run a 2kw gen and run intermittent high draw stuff without overloading the generator or undercoating it when the high draw stuff is off and you want to resume battery charging.

 

[sunshine_eggo]

Yeah so it's not like other inverter chargers.

It is the same. It simply has an added feature. The statement still holds true. It can't invert and charge at the same time. If powerassist is activated, charging immediately stops.

This is a handy feature for an undersized generator when intermittent loads exceed generator capacity. Benefitted from it many times.

 

[Checkthisout]

It is the same. It simply has an added feature. The statement still holds true. It can't invert and charge at the same time. If powerassist is activated, charging immediately stops.

This is a handy feature for an undersized generator when intermittent loads exceed generator capacity. Benefitted from it many times.

?

Well yeah if it did then it would overload the Gen like the EG4.

 

[John Frum]

It is the same. It simply has an added feature. The statement still holds true. It can't invert and charge at the same time. If powerassist is activated, charging immediately stops.

This is a handy feature for an undersized generator when intermittent loads exceed generator capacity. Benefitted from it many times.

But can it bypass and invert at the same time?
I'm guessing that even though it can syncronize with the upstream source it doesn't, but I'm not sure.

 

[Checkthisout]

But can it bypass and invert at the same time?
I'm guessing that even though it could syncronize with the upstream source it doesn't, but I'm not sure.

Yes, it bypasses and inverts at the same time in assist mode.

This is what makes its different than other inverter chargers.

 

[photomankc]

Okay.

So for the time being I'm going to live with bypass mode and set charge current to 20A. That will leave me some room to operate most of my stuff as long as I'm aware of not doing two high current things together, which is fine as Im still building. I'll start hunting for a 30A to 35A charger to setup separate from the inverter. I already have a nice set of generator-only 20A outlets that I could use for that. With that charge current a 10KW setup would be a nice sweet-spot and with solar added in I think it would handle 15KW without much trouble too.

I appreciate the info, thanks!!

 

[sunshine_eggo]

But can it bypass and invert at the same time?
I'm guessing that even though it can syncronize with the upstream source it doesn't, but I'm not sure.

It does.

Dexter demo-ed zero export on 120VAC - basically a grid-tie inverter that won't backfeed with the appropriate sensor installed:

VICTRON 24V Multiplus II 2x120v Purchase Availability

Do we have any owners of a Multiplus II 2x120V on the Forum yet? Yes, ordered and received in early September from: https://www.continuousresources.com/collections/pure-sine-wave-inverter-with-charger/products/victron-energy-multiplus-ii-24-3000-70-50-2-x-120v

diysolarforum.com

 

[John Frum]

It does.

Dexter demo-ed zero export on 120VAC - basically a grid-tie inverter that won't backfeed with the appropriate sensor installed:

VICTRON 24V Multiplus II 2x120v Purchase Availability

Do we have any owners of a Multiplus II 2x120V on the Forum yet? Yes, ordered and received in early September from: https://www.continuousresources.com/collections/pure-sine-wave-inverter-with-charger/products/victron-energy-multiplus-ii-24-3000-70-50-2-x-120v

diysolarforum.com

Makes me suspect that is why only distributers are supposed to have full access to the configuration.

 

[sunshine_eggo]

Makes me suspect that is why only distributers are supposed to have full access to the configuration.

Yep. Victron only complies with certain grid standards, NONE of which include the U.S. grid, and a password is required to set or change the grid standard.

EDIT: "NONE" was "one" - so wrong.

 

[AstroBob]

I'm a little confused with this thread. The folks I know with very large 5th wheel RV's and other large TT's all seem to get by quite well with no more than <=4500 watt gennys when boondocking. (including PV, of course). With my own small (18ft) trailer, I run the 13K AC and micro with a 2200 honda. I have a rural property with a 750 sq ft cabin, and I can run the furnace and fridge and most everything else on a wen 3800 gen. I can't possibly imaging why a tiny house on a trailer would require such incredible amounts of energy to sustain them, even in a cold climate.

Perhaps a mobile military communications center or something. lol.

Isn't the entire point of a tiny house to be efficient?

Is not the "combi boiler" a gas powered unit?

So, where does the need for 5Kw power come in? Where are these massive loads coming from? I am curious.

 

[photomankc]

I'm a little confused with this thread. The folks I know with very large 5th wheel RV's and other large TT's all seem to get by quite well with no more than <=4500 watt gennys when boondocking. (including PV, of course). With my own small (18ft) trailer, I run the 13K AC and micro with a 2200 honda. I have a rural property with a 750 sq ft cabin, and I can run the furnace and fridge and most everything else on a wen 3800 gen. I can't possibly imaging why a tiny house on a trailer would require such incredible amounts of energy to sustain them, even in a cold climate.

Oh were it just the generator I'd have no issue at all. The 3000W covers most anything I really do beyond starting very large inductive loads. But when it's going to spend 4 to 6 hours with 1600W siphoned off then its a different story. I imagine once solar is in place that might not be as much of a concern so I grant that.

Isn't the entire point of a tiny house to be efficient?

Probably all manor of reasons people get whatever it is that's called a "tiny house" now. For myself we built the largest structure we could afford to dry in as a getaway cabin. It's not a garden shed and its not really a house. It kinda sits in the middle. For us efficiency is a distant 3rd or 4th. Main consideration was to have a system we could grow into and expand and that could handle most tasks without power management being top-of-mind. I also prefer these Chinese electronics to spend most of their lives working in the low end of their specs. Will be building this system like the cabin itself. A little bit at a time.

So, where does the need for 5Kw power come in? Where are these massive loads coming from? I am curious.

As above, for me its having lots of headroom if someone is showering with the pump running, the microwave is on, and my daughter is using the kettle for tea. Were it only ever going to be me there I'd live without a lot of that, but since it's wife and daughter, making sure for the most part power is not something to juggle I went oversized on the inverter.


Not really trying to refute you here either, just explaining where I'm coming from on my system.

 

[sunshine_eggo]

If I didn't have a Victron with powerassist, I'd be pissed with generator charging too. My generator can only output 15A per 120V leg, so I'm limited to < 1800W PERIOD.

PA has saved my bacon multiple times.

 

[AstroBob]

Oh were it just the generator I'd have no issue at all. The 3000W covers most anything I really do beyond starting very large inductive loads. But when it's going to spend 4 to 6 hours with 1600W siphoned off then its a different story. I imagine once solar is in place that might not be as much of a concern so I grant that.

Alrighty. I thought you said 5K watts, not 3, but maybe I wasn't paying attention. On my off toad trailer, I have 200watts solar, + 600 portable in needed, 206Ah LifePo4 + 2000 watt inverter if needed. Obviously, I don't run the 13K AC off the batts, and rarely the micro. Water heater and furnace are propane, as is the fridge.

The small genny is just to power the AC when needed, and to charge the batts when no solar, so maybe not all that dissimilar to the tiny house thing, I venture. - or maybe not.

Probably all manor of reasons people get whatever it is that's called a "tiny house" now. For myself we built the largest structure we could afford to dry in as a getaway cabin. It's not a garden shed and its not really a house. It kinda sits in the middle. For us efficiency is a distant 3rd or 4th. Main consideration was to have a system we could grow into and expand and that could handle most tasks without power management being top-of-mind. I also prefer these Chinese electronics to spend most of their lives working in the low end of their specs. Will be building this system like the cabin itself. A little bit at a time.

Yeah, I get it. I am no EE, just trying to compare your interesting project with a somewhat similar use case. It seems to me that with a "Tiny" house you have a huge advantage over any travel trailer or camper in that you can insulate to whatever specs you want. Travel trailers are mostly all very poorly insulated. I am just speculating but from what I know, good insulation isn't cost prohibitive, and can make a large difference in energy consumption. Sounds like low hanging fruit to me, anyways.

As above, for me its having lots of headroom if someone is showering with the pump running, the microwave is on, and my daughter is using the kettle for tea. Were it only ever going to be me there I'd live without a lot of that, but since it's wife and daughter, making sure for the most part power is not something to juggle I went oversized on the inverter.

Do you mean an RV style water pump, or this a pump part of the combi unit? My RV pump doesn't use much power. Hard to avoid the power drain from the micro, but I don't use mine much, so not a problem for me off grid. But it's understandable that you want to include that.
I do all of my cooking with propane, it sounds like you need/want electric. That's cool.

Not really trying to refute you here either, just explaining where I'm coming from on my system.

It really didn't sound like you were refuting my comments, I was just expressing my interest in your project. It sounds like fun to me.