how to boast your Victron Multiplus 2,4KW inverter with a cheap 3500W one to 5,9kw

[Na Mara]

Originally Posted by CaptainRivet

You are welcome.
Just be carefull, pulling 2,4kw from Victron multi and 2,3kw is 4,7kw / 12,5V = 376A with inverter losses and normal house load running too you are at 400 till 420A const. for 10min. That means your whole installation must be speced for that and at max roughly 0.3C of your bank, which means your bank should have around 400A/0.3=1300AH capacity, min 1000AH if you habe LFP cells like EVE or Lishen or your drop-in can do 1C max (which is standard), if you have Winston cells with 2C cont a 700AH bank will do that, the newer 3 C cells a 400AH bank is enough. That’s needed for a) to keep the ripple of both inverters in an acceptable range and b) your bank stays in balance on the long run.
The heavy duty install stuff is normally rated for 300A continues. I use NH fuses and build my own busbars from 30mm x 7mm silver plated cooper bars which is rated for 1500A.
Off the shelf only Victrons Lynx Distrubutor comes to my mind rated for 1000A.

Good information for others but I am good I think. I have 600Ah LFP running through a Lynx distribution limited to 500A by the external Lynx BMS that is part of that system. Its all belt and braces. The cooker I am needing to power maxes out at 3.75kW, so I shouldn't need to go much above 350A continuous.

First I am going to try and live within the 2.4kW of the Victron inverter charger, but if that becomes a bind then I will certainly look into your solution here as the alternatives (parralleling another Victron unit or buying in a 2kW power station and feeding its output into the AC input of the victron) are both much more expensive than your solution (though I would get an extra 2kWh of battery storage with the power station).

[CaptainRivet]

Originally Posted by s/v Jedi

IAMS is cat and dog food

Well RV croud and also Electrodacus community is running them frequently since years without too many problems. For IAMS i forgot to mention only the LF frequency models.
Yes these are low cost inverters compared to victron but hold up quite well, cats and dogs need to eat too. You get what you pay for, its not a Victron or Studer but its sufficent for occasional use inside the spec (for the all I mentioned), i would be a bit carefull at the upper end and consider the constant load rating as peak load, then you are definitley safe.
Problems with all that lower priced is final Q&A directly from china: if you get one that runs out of the box and then longer then 2 weeks you get a good one that holds up a long time...so amazon is your friend here.
In the boost setup these run not that often so totally sufficent.

[CaptainRivet]

Originally Posted by Na Mara

Good information for others but I am good I think. I have 600Ah LFP running through a Lynx distribution limited to 500A by the external Lynx BMS that is part of that system. Its all belt and braces. The cooker I am needing to power maxes out at 3.75kW, so I shouldn't need to go much above 350A continuous.

First I am going to try and live within the 2.4kW of the Victron inverter charger, but if that becomes a bind then I will certainly look into your solution here as the alternatives (parralleling another Victron unit or buying in a 2kW power station and feeding its output into the AC input of the victron) are both much more expensive than your solution (though I would get an extra 2kWh of battery storage with the power station).

Lynx you are fine from install side for boost mode.
Would recommend get a solartronic HF one, they are made in germany and maybe a 100 Euro more expensive then the other i mentioned butvthey work remote out of the box and have good support. I would go for their 4kw one so in case your victron dies, that can run the whole show. https://www.solartronics.de/spannung...lay-fs4000d12v
Tell them you have LFP and need remote on/off, they will modify for free. Oversized inverter is always good, they live longer and less problems.
Your multi will be running a lot in overload mode, especially if your in hotter climate area, not healthy for it...
My Bartscher 3 burner commercial induction cooktop is 3500W limited and running 2 at level 7 is around 2400W, limit of the multi which gets used frequently like this as most efficent also to boil. But its induction so cos pi is not so good (mine is commercial grade so not that bad) and inverter needs to supply 2800W...overload. i often cook with the oven, roast for 30-40min at 180 degress (1300w) but then i need to run 1 or 2 burner induction at middle level for the side dishes for short periode 5-15min of time which is again 1500W so at around 3000 total...overload. a 3500 Victron would do it 95% of time but its only 2,4kw.

[skenn_ie]

Originally Posted by donradcliffe

Only one problem. If the inverter outputs are not in phase, there's going to be a lot of smoke. The dual multiplus system was designed to prevent that problem, but I wouldn't bet my boat that the chinese inverter was.

Why to you think your boat was set up to never allow shore power or inverter or genset to operate at the same time?

Wire the new one to a separate circuit and power the occasional-use appliance to it.

[MVDarlin]

Recommend you change galley to propane. Also my outdide 2x burner covered Cuisinart propane bbq makes an excellent oven with up to 600* heat for all baking and grilling needs. Just add a pizza stone.

[CaptainRivet]

Originally Posted by skenn_ie

Wire the new one to a separate circuit and power the occasional-use appliance to it.

Thats pain in the ass and a lot extra cabeling. Also not necessary as Jedi pointed out the Victron synchronizes the phase. Had that before, not recommended...now running this setup since 6 months absolutly reliable and not a single flaw... really tested this out before posting here. The victron stopped humming and is very quite now compared to before.
Also each inverter seperatly is not capable or runs on the absolute edge. You don't wanna run an induction cooktop off a cheap chinese HF inverter, the bad cos pi of induction and phantom loads that overloads HF inverter quickly without you realize it and kill it very quick (really bad for the FETs in the HF inverters they die much faster) the multi alone cannot handle it. Microwave is even worse.
Combine them together and each does comfortably his job but, the cheap HF supplies base load and victron the surge, phantom loads and peaks.
you are much more flexible as the 2nd is only added when the Victron would go in overload. This creates also less energy consumption as only one inverter is on stanby or in use...and a 3,5kw needs easy 40W xontiniously in standby, that adds up....

[CaptainRivet]

Originally Posted by MVDarlin

Recommend you change galley to propane. Also my outdide 2x burner covered Cuisinart propane bbq makes an excellent oven with up to 600* heat for all baking and grilling needs. Just add a pizza stone.

Sure and then run around, store dozen adapter and still always miss the one you need.... then noone wanna refill the bottle as not their standard...and if you finally get it refilled you have to carry and transport that heavy bottle around. If you world circumnavigate time consuming and always a hassle...happy i got rid off it
My induction cooktop and inverter oven microwave, steamer combo is running from LFP bank constantly refilled for free by the sun.
Add to that danger of gas....
Thrown out the gas oven but kept gas stove underneath the induction cooktop as backup.

[Shaneesprit]

You cannot read the name plate on a Chinese product and believe the output.
That’s really the worst part, it’s not always that the quality is bad, it’s the outrageous output claims.

[skenn_ie]

Originally Posted by Shaneesprit

You cannot read the name plate on a Chinese product and believe the output.
That’s really the worst part, it’s not always that the quality is bad, it’s the outrageous output claims.

A recently developed material "Chinesium" One step up from pure sh%$e.
A read a report a while ago about a chinese battery. It was a large battery box with a small battery and some concrete bricks in it.
Inverters. I suggested that I would bench-test one when I got it, and the supplier then refused to sell to me.

[s/v Jedi]

Originally Posted by skenn_ie

A recently developed material "Chinesium" One step up from pure sh%$e.
A read a report a while ago about a chinese battery. It was a large battery box with a small battery and some concrete bricks in it.
Inverters. I suggested that I would bench-test one when I got it, and the supplier then refused to sell to me.

Please add the link to the article on the battery with a concrete brick inside

I find your rejection of Chinese manufacture amazing! I don’t think I could do without my iPad, iPhone, Lithium batteries etc.

[skenn_ie]

Major names, fine. No-brand, not. About 15 years ago, I bought done motor-bike locks as samples. One stroke with a hacksaw cut into them significantly. I was able to bent the soft iron over my knee and the locks didn't engage properly. A friend bought a tower for a wind turbine. It collapsed in a moderate wind. The structure was soft iron, not even mild steel. I have bought and otherwise seen electrical stuff that was marked CE, but couldn't possibly be compliant (I used to test stuff for CE compliance).
SOME No-brand stuff is OK, but I check inside and out before using for critical functions.

[skenn_ie]

Major names, fine. No-brand, not. About 15 years ago, I bought done motor-bike locks as samples. One stroke with a hacksaw cut into them significantly. I was able to bent the soft iron over my knee and the locks didn't engage properly. A friend bought a tower for a wind turbine. It collapsed in a moderate wind. The structure was soft iron, not even mild steel. I have bought and otherwise seen electrical stuff that was marked CE, but couldn't possibly be compliant (I used to test stuff for CE compliance).
SOME No-brand stuff is OK, but I check inside and out before using for critical functions.

[CaptainRivet]

Originally Posted by skenn_ie

Major names, fine. No-brand, not. About 15 years ago, I bought done motor-bike locks as samples. One stroke with a hacksaw cut into them significantly. I was able to bent the soft iron over my knee and the locks didn't engage properly. A friend bought a tower for a wind turbine. It collapsed in a moderate wind. The structure was soft iron, not even mild steel. I have bought and otherwise seen electrical stuff that was marked CE, but couldn't possibly be compliant (I used to test stuff for CE compliance).
SOME No-brand stuff is OK, but I check inside and out before using for critical functions.

That why they are forums and you tube. There are several good and cheap chinese inverter out their that are now used over more then 5 years (some 24/7) by a big crowd.
If you wanna avoid directly from china best in the
Midpriced is german build solartronic (sure they source complete boards from china) you get a real 4kw 12V inverter that can do 6kw peak for 590Euro and they stand by there garantuee. Rv crowd is very happy with them and a wide range of proffesional RV installer use them as budget option to victron.
Will Prowse or the eletrodacus forum is a good source. Eg giandel, Edecoa are good chinese ones...

[Na Mara]

I still like the idea of boosting the output of my inverter using the power assist, but if you are shelling out 600euro why not just go the whole hog and get another multiplus and parallel it with the first one. That extra 600 euro then gets you all the connectivity and ease of monitoring through the bus system. It also gets you redundancy in charging and inverting.

I’ve just started putting my multi through its paces and it is an awesome piece of tech. seriously life changing.

[s/v Jedi]

Originally Posted by Na Mara

I still like the idea of boosting the output of my inverter using the power assist, but if you are shelling out 600euro why not just go the whole hog and get another multiplus and parallel it with the first one. That extra 600 euro then gets you all the connectivity and ease of monitoring through the bus system. It also gets you redundancy in charging and inverting.

I’ve just started putting my multi through its paces and it is an awesome piece of tech. seriously life changing.

Not only that, but it also doubles the PowerAssist feature. I have two Multiplus 3000’s in parallel for 6000VA and I also have a 6kW genset so I can support a 10kW load easily

Think of having a Honda 2kW generator… supports 7kW this way!