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

[CaptainRivet]

Hi all,


I meanwhile use a cheap 350Euro 3500W Edecoa HF inverter as boost inverter for a Victron Mulitplus 12/3000/120 for some time and though that will help some of you too.

Reason is the victron covered 24/7/365 my everyday needs but when i converted my cat from gas to all electric galley the VIctron Multi is not enough to drive all kitchen appliances, means induction stove and oven in parallel. So I need for maybe 10min each 2nd day more then Victron can deliver, doesn't justify a 2nd Multi.

But I had my old cheap chinese 3500W Edecoa inverter lying around and figured out how to use it to boost the victon for this 10min each 2nd day.

The 2nd inverter Edecoa is steered via the Multi and acts as fake generator.

the Multi runs 24/7/365 but the Edecoa gets only switched on by the Multi if the Multi's load is above 2450W, which is normally only when we are cooking big time.

You can simply do that in an "off grid installation" by

a) connecting the 110V/230V ouput of the 2nd inverter/Edecoa to the multi AC in.
b) connect the remote cable from the Edecoa inverter to the primary relay of the victron multi. the relay is located at the top right corner at the Multi, on Multi 2 you find it at the bottom on the green connectors. Connect the minus to com on the relay, the plus connects on RO on the relay.
c) now connect to multi via USB to MK3 interface with a computer and VE configure software. now go to

1) inverter tap and click "ground relay" so that the multi also connects neutral and earth when the Edecoa inverter delivers 230V into AC in (as its fake and not a real grounded generator).

2) charger tap: disable "enable charger", you have no grid connected but a fake generator=> I use the BT dongle and keep the charger enabled but switch via the BT dongle to "inverter only mode". i use a transfer switch connected o n AC in and have on one connection the 2nd Edecoa inverter and other conncetion shorepower connected. So when i use shorepower (which is extremly seldom) then I switch that transfer switch to shorepower and turn on the charger via the BT dongle.

3)Virtual switch choose "don't use VS (virtual switch)", you should actually have that with the SBMS as you need the BMS assistent for the SBMS anyhow.

4) Go to assistent tap and choose the assistent "generator start and stop assistent". then start the assistent:

first question "tick Option1: use primary programmable relay"
2nd question: "tick Option "close the relay contact to start generator"
3rd question: " tick Option "start on load condition"
4th question next question is where you can determine the threshold from when the generator or in this case your 2nd inverter should kick in. the multi can do 2400W constinous, so i have the following values: start generator when load higher then 2450W for 5 second" and "stop generator when load lower then 2350W for 10 seconds"



thats it. I steer the Multi via the BT dongle and connect app and i recommend that over the remote control. Reason is that via Connect app you can choose "inverter" only.

To choose how much current the 2nd inverter takes over you use the power assist feature, means if you put there 10A then after the Victron Multi switches the 2nd inverter on (from 2450W on), it will take up to 10A with 230V=2300W so you have 2450W+2300W=4750W inverter power. means when Victron switches on the 2nd inverter at a load of 2800W, the Edecoa will take 2300W and the Victron 500W. The Victron also takes peak and surge loads while the cheap 2nd HF inverter supplies the base load up to eg in my case 10A=2300W, all above comes from the victron. like this a high surge cannot destroy your cheap inverter, as the Victron will take care. the switch over is like USP so no loss of data etc.

like this the Edecoa runs maybe 10min each 2nd day and will last as long as the Victron multi which runs 24/7/365.

hope that helps some of you, especially in a 12V setup as its hard to find inverters above real 2,5 kw and you most likly will need only more the 2,4kW in rare situations so the cheap HF inverter is enough.
that also works with the smaller Multi, I think the Multi 1600 is the smallest with power assist, thats what the feature you need for this setup. that setup also works if you have a Multi and a Phönix inverter and wanna connect them in series...

CaptainRivet

[Na Mara]

This is a quality post. Awesome idea and execution that really helps us 12V guys make the switch to electric cooking. I owe you one CaptainRivet!

[sailingharry]

Quite innovative! While your design is notable, it really highlights the incredible power and flexibility of the Multiplus!

[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?

[s/v Jedi]

Here’s the video:

https://www.youtube.com/watch?v=SsTkgoN6ENM

[s/v Jedi]

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?

The Victron PowerAssist synchronizes the phase. This is the big hit from Victron that everything turns around. Not just with this trick but also with real generators on the input that are too small to carry the load but more than enough for avg. power requirements.

[CaptainRivet]

Originally Posted by s/v Jedi

Here’s the video:

Yes great guy, Andy from offgrid garage. He actually got that tip from me, didn't know he made a video about that.
Modifying the chinese inverter to be able that the electrodacus BMS can switch it remotly on or completly off is done through Electrodacus community since years. And having trouble finding 4-5kw inverters in 12V i tried this config with the victron assistent.
But instead BMS the Victron is steering the Chinese HF inverter now and only the victron is steered by BMS.

using the generator start/stop assistent is the key to have the one victron on 24/7 and only start the 2nd inverter when needed. I also do this with 2 Victrons Multi and instead have 2 running on standby when paralleling them, the master multi is on standby only and switches on the slave multi aka fake generator when needed.

If you just connect the 2nd inverter to AC in and use power , both inverters have to be always on and run on standby or you need to manually switch on the 2nd one when need more load.

[CaptainRivet]

Originally Posted by Na Mara

This is a quality post. Awesome idea and execution that really helps us 12V guys make the switch to electric cooking. I owe you one 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.

My install is speced for 600A const and i have a 1100AH bank. Thats not cheap install material and you have to be metricously when installing as 400-600A can easily cause a fire when a connection is faulty. Thats the reason no inverters above 3kw @12v can be found, Victrons 5kw Quattro is the only execption.

[CaptainRivet]

Forgot an cannot add above:
The Victron multi 3000/16/120 delivers up to 5,9kw in this setup and you need to run 3x6sqmm cable on the AC 230V AC out to the Main AC distribution panel and a 32A or 40A double pole breaker /OCD is needed.

[more]

https://www.tiktok.com/@dalmatinskip...11209367309595

goodby 1 mil € +- almost new lagoon 45 fire start on eletric wire 20 fire fithing tank dont stop fire.

[HeinSdL]

Originally Posted by more

https://www.tiktok.com/@dalmatinskip...11209367309595

goodby 1 mil € +- almost new lagoon 45 fire start on eletric wire 20 fire fithing tank dont stop fire.

what is that after 'start...' ?

[Loredo]

Absolutlely BRILLIANT "outside the box thinking"!
My redneck solution to a somewhat similar situation was to use a 24V /5KW cheapo chinese inverter to power the electric galley only. I kept the already existing 2.4KVA Mastervolt inverter for everything else. There will be never enough emphasis on wire size and competent installation when it comes to high AC power from inverters / batteries.

[more]

Originally Posted by HeinSdL

what is that after 'start...' ?

chinese inverter .

[CaptainRivet]

Originally Posted by more

chinese inverter .

Well nearly all build in China, like nearly all electronics....
Quality well priced inverter are Giandel,Edecoa and IAMS. Solartronic made in Germany are well made HF inverters too, their 4kw 12V is 500Euro.
All tested by a big crowd of RVers, wouldn’t use unknown and nobrand ones as that ends like the Lagoon above

[s/v Jedi]

Originally Posted by CaptainRivet

Well nearly all build in China, like nearly all electronics....
Quality well priced inverter are Giandel,Edecoa and IAMS. Solartronic made in Germany are well made HF inverters too, their 4kw 12V is 500Euro.
All tested by a big crowd of RVers, wouldn’t use unknown and nobrand ones as that ends like the Lagoon above

IAMS is cat and dog food