Victron Multiplus 24/3000 cutting out at 750W

[AfterShock]

Good day gents,

First of all thank you again for helping me sorting out the type of system I needed 5 months ago. I have long waited for my RV trailer to arrive and I just got it 2 weeks ago. I started installing everything and I ran into an unforeseen issue that I am not sure how to fix. First of all, here is the cabinet (minus the batteries as it gets crowded in there with them for the purpose of the pictures)



Here are the components of my system:

2 x 200ah 12V lithium batteries installed in series (runs at about 27V)
Victron BMV smart / shunt
Lynx distributor
Multiplus 24/3000/70
MPPT 150 / 60
800W of solar panels (not currently installed but roughed in)
Orion 24/12 buck converter (deleted from the system, explanation below)

As far as I can tell, I went overkill on all the wires for a 24V system. The shore power is a 10/3 wire, then 6/3 tek wire from the inverter to the electrical panel. All other wires a 00 and 6 awg.

First of all, we had lengthy discussions 5 months ago concerning running 24V instead of 12V. The benefits were that I could double the solar array with the same MPPT, and that overall I would require smaller wiring than with 12V. the downside was the need to run a 24/12 Buck converter to feed the 12V side of my electrical panel.

Turns out, the RV that I purchased does not require a 12V battery to function, as there is a built in converter that feeds the entire 12V system when plugged into shore power. Being that as long as the inverter is on I always have 120V going to the panel, the converter is always on as well and all my 12V components work. This eliminated the need for the buck converter altogether although I did find that out too late. When I tested the entire assembly with the buck converter wired in, it instantly fried itself, I am assuming that was because of the built in converter vs the buck converter feeding the same 12V system. Thankfully, nothing else fried.

Now here is where I have some issues that I'm not certain of the source:

1. When I run the inverter but switch off the batteries, the inverter briefly goes into "low battery" alarm but then quickly goes into bulk or float mode and starts making strange sounds. The inverter is still functional at this point with the shore power

2. when I start running electrical equipment like the fridges or the fan of the AC, I can see on my Victron app that it goes up to about 750W and then cuts out and resets after about 20 seconds. Being that this inverter should run 3000W, I am a bit puzzled by the issue.

3. Shouldn't the inverter simply by-pass itself when plugged into shore power? I cannot understand why it would shut itself off considering it's not actually inverting when going from 120 to 120

4. Are there settings on the inverter that can fix this issue? I do have the dongle although I have not plugged it into my laptop yet.

P.S. As I am looking at my pictures I just realized that I am missing a ground wire between the inverter and the MPPT. However these issues occurred before the MPPT was even wired into my system yet.

Any help would be appreciated.

 

[John Frum]

Just a wild guess.
For a test turn off the breaker for the ac2dc converter and see if anything changes.

 

[MisterSandals]

When I tested the entire assembly with the buck converter wired in, it instantly fried itself, I am assuming that was because of the built in converter vs the buck converter feeding the same 12V system.

Hmmm, i would fell better about my system if i understood this better (completely).

1. When I run the inverter but...

Seems you have 2 inverters, are you talking about the Multiplus here?

Turns out, the RV that I purchased does not require a 12V battery to function, as there is a built in converter that feeds the entire 12V system when plugged into shore power. Being that as long as the inverter is on I always have 120V going to the panel, the converter is always on as well and all my 12V components work.

My money is on your 2 inverters not working together properly.
Is it possible that your Multiplus is feeding your RV's inverter/charger (which gets 120V AC and acts like it is on shore power) which is in turn trying to charge your batteries? And when this charging process starts in 20 seconds, it overloads your Multiplus?

 

[DJSmiley]

Did you measure the voltage at the terminals of the inverter when drawing a eg 600W load?

If there is a huge drop compared to the voltage directly from the batteries, you have to check the wiring. Based on the images, the wire gauge looks ok (But I can't see the total length), but the higher the current draw, the more important is proper wiring (torque, crimp quality)

It does look ok tho, but I'd verify with a meter.

Also, I assume you did set the Victron to LFP in it's settings with the MK3 USB?

And yes, if you have any other charger/inverter, disconnect it. I don't know why you should leave that installed when you have a Victron multiplus (= high quality inverter/charger)

 

[AfterShock]

Hmmm, i would fell better about my system if i understood this better (completely).

Seems you have 2 inverters, are you talking about the Multiplus here?


My money is on your 2 inverters not working together properly.
Is it possible that your Multiplus is feeding your RV's inverter/charger (which gets 120V AC and acts like it is on shore power) which is in turn trying to charge your batteries? And when this charging process starts in 20 seconds, it overloads your Multiplus?

So this "built in converter" that came with the RV is one of the breakers on the AC panel of the RV which is also connected to the DC side of the panel and feeds the 12V DC system.

However, my batteries and that entire electrical cabinet shown is completely independent of the 12V system and isn't connected to the 12V system at all currently. Unless somehow some interference happens with the chassis ground connection? I am no electrical expert so I don't know if that's possible but seems unlikely.

I deleted the wiring from the Orion buck converter to the 12V system, which was the only way the converter could interfere with the Multiplus inverter that I know of.

I could try to run some tests with the converter off, the only issue with that is that literally nothing works on a trailer without 12V power (even the AC needs 12V and 120V to work). That means my tests would be limited to using the electrical outlets.

 

[DerpsyDoodler]

So this "built in converter" that came with the RV is one of the breakers on the AC panel of the RV which is also connected to the DC side of the panel and feeds the 12V DC system.

However, my batteries and that entire electrical cabinet shown is completely independent of the 12V system and isn't connected to the 12V system at all currently. Unless somehow some interference happens with the chassis ground connection? I am no electrical expert so I don't know if that's possible but seems unlikely.

I deleted the wiring from the Orion buck converter to the 12V system, which was the only way the converter could interfere with the Multiplus inverter that I know of.

I could try to run some tests with the converter off, the only issue with that is that literally nothing works on a trailer without 12V power (even the AC needs 12V and 120V to work). That means my tests would be limited to using the electrical outlets.

Have you reached out to victron tech support?

 

[AfterShock]

Did you measure the voltage at the terminals of the inverter when drawing a eg 600W load?

If there is a huge drop compared to the voltage directly from the batteries, you have to check the wiring. Based on the images, the wire gauge looks ok (But I can't see the total length), but the higher the current draw, the more important is proper wiring (torque, crimp quality)

It does look ok tho, but I'd verify with a meter.

Also, I assume you did set the Victron to LFP in it's settings with the MK3 USB?

And yes, if you have any other charger/inverter, disconnect it. I don't know why you should leave that installed when you have a Victron multiplus (= high quality inverter/charger)

I will measure them tonight at the terminals and double check.

I did not change any settings yet with the MK3

The charger inverter that is built in should not interfere (in theory) in any way that I can think of. The Victron Multiplus simply isn't connected to the 12V system. However, I do have another Orion unit on order... I could potentially delete the built-in converter and run the 12V system on the Orion buck converter.

 

[MisterSandals]

my batteries and that entire electrical cabinet shown is completely independent of the 12V system and isn't connected to the 12V system at all currently.

Being that as long as the inverter is on I always have 120V going to the panel, the converter is always on as well and all my 12V components work.

This sounds like they are NOT completely independent.

It sounds like your appliances may be running off your RV's inverter and not the Multiplus? Or is your Multiplus feeding the RV's original shore power plug (and not the Multiplus?)

 

[MisterSandals]

did set the Victron to LFP in it's settings with the MK3 USB?

I did not change any settings yet with the MK3

You're running a multi voltage system that accepts many different kinds of batteries without setting it up at all? Wow.

 

[DerpsyDoodler]

This sounds like they are NOT completely independent.

It sounds like your appliances may be running off your RV's inverter and not the Multiplus? Or is your Multiplus feeding the RV's original shore power plug (and not the Multiplus?)

If this is the case, he's lucky he hasn't found any magic smoke or worse, yet. I recommend disconnecting power until the problem can be traced down.

 

[AfterShock]

This sounds like they are NOT completely independent.

It sounds like your appliances may be running off your RV's inverter and not the Multiplus? Or is your Multiplus feeding the RV's original shore power plug (and not the Multiplus?)

I am not exactly sure what you're implying.

The Multiplus is the only thing feeding the AC side of the RV panel, meaning the shore power connection, solar and 24V batteries are all connected to the Muliplus.

The converter is connected to the AC panel as a 15 breaker. I am assuming that since it's job is to convert 120V to 12V, it shouldn't run interference with the 120V side of things... But I do not know for sure. Any capability that is has to charge 12V batteries shouldn't matter since there is no 12V running back to the Multiplus.

 

[DerpsyDoodler]

Does the inverter log any errors or codes when it resets?

 

[AfterShock]

Does the inverter log any errors or codes when it resets?

The "overload" light does not come on and it shuts completely off, I did not connect with the dongle yet to see the log but will do so tonight.

 

[MisterSandals]

The "overload" light does not come on and it shuts completely off

This sounds like your batteries are not sufficiently powering your Multiplus.
Can you explain a little about your battery bank, maybe with a pic of how its wired and its current voltage as tested with a volt meter?
If you've not setup your Multiplus, who knows what battery type it is set to, probably lead acid since that is probably the safest but i dunno. This would imply that your battery(s) are not fully charged (thus the need to investigate battery voltage).
You did connect the battery(s) to the Multiplus before connecting anything else, right?

 

[AfterShock]

You're running a multi voltage system that accepts many different kinds of batteries without setting it up at all? Wow.

So far I am just testing things. Even if I disconnect the batteries entirely, I still run into the exact same issue where the inverter shuts down with just 1 regular RV fridge and 1 mini fridge drawing power.

This sounds like your batteries are not sufficiently powering your Multiplus.
Can you explain a little about your battery bank, maybe with a pic of how its wired and its current voltage as tested with a volt meter?
If you've not setup your Multiplus, who knows what battery type it is set to, probably lead acid since that is probably the safest but i dunno. This would imply that your battery(s) are not fully charged (thus the need to investigate battery voltage).
You did connect the battery(s) to the Multiplus before connecting anything else, right?

The batteries were reading at 27V from the smart BMV and showing 100% charge as well. There is actually no difference in functionality for the multiplus whether I'm only on battery or only on shore power or both.

I did originally test the inverter with batteries only, no issues. Then installed the shore power, again no issue. When I switch the batteries off and keep shore power on, the inverter makes strange faint sounds but still functions. Nothing is getting hot, no odors coming from anywhere.

When I start using appliances inside the trailer, things are normal until I draw about 750W and then it shuts off, regardless of being on battery, shore power or both. The Victron app readings from the smart BMV all appear completely normal until shut downs.

 

[rmaddy]

1. When I run the inverter but switch off the batteries, the inverter briefly goes into "low battery" alarm but then quickly goes into bulk or float mode and starts making strange sounds. The inverter is still functional at this point with the shore power

Don't run the inverter without the battery connected to it. If you don't want the batteries to be charged by the Multiplus while using shore power you can set the current limit to 0.

4. Are there settings on the inverter that can fix this issue? I do have the dongle although I have not plugged it into my laptop yet.

Stop everything. Disconnect shore power. Connect the inverter to the battery. Connect the inverter to your computer. Run VE Config or VictronConnect and make sure all of the settings are correct for your setup.

Once the battery is connected and the settings are verified you should get better results.

And be sure you read the Safety, Installation, and Settings sections of the Multiplus manual.

 

[MisterSandals]

Don't run the inverter without the battery connected to it.

I would bet that the manual (that booklet still in the shrink wrap packaging) indicates that you MUST have a battery connected, first (and always).

Connect the inverter to your computer.

Is this different/better than using the app? I dunno, just asking.

Once the battery is connected and the settings are verified you should get better results.

Bingo.

 

[rmaddy]

Is this different/better than using the app? I dunno, just asking.

I have my MultiPlus connected to a Raspberry Pi running Venus OS (same as a fancy GX device). If I try to use VictronConnect from my iOS device, there is no access to settings (despite having the bluetooth dongle). But if I disconnect the MK3 from my Raspberry Pi and use it to connect to my Mac, then I can access the settings.

 

[RickP]

The Multiplus 24/3000 is not a Bluetooth device, so either the MK 3 USB or BT dongle is required to program it. This unit’s default settings are programmed so that it runs from shore power first if it is available, switches to batteries (like a ups) automatically when shore power fails or is absent. It will also supplement shore power with battery power if the incoming power is below voltage spec.

1. You should not turn the batteries off. The inverter is not “inverting” shore power, it’s passing it through via a relay. When you turn off the batteries, the inverter reads no voltage and is trying to “fix” the problem. If you haven’t changed the factory settings, the Multiplus “turns off” the batteries internally when sufficient shore power is available.

2. Your unit must be programmed for your battery type and available amp hours. It’s possible it is cutting off because it thinks (based on settings) it is reaching its battery limit.

3. There are also incoming amperage limit settings, as well as output limits in the programming. The Multiplus is one of the most programming-capable inverter chargers out there. It’s really a marvelous device. That also means that a lot of this can be set wrong or interact in hard-to-trace ways if you don’t put the required time into the manuals, Victron videos and web articles, etc to know what each page of programming does.

4. If you’d like to run things only when shore power is available, and never from batteries, there are connections available on the MP for those, as well.

You’ve got a great unit there! Take the time to make sure you get it set up right, even enlisting help from your dealer or a pro. Set up right, it’ll deliver everything the spec sheet shows.

 

[AfterShock]

The Multiplus 24/3000 is not a Bluetooth device, so either the MK 3 USB or BT dongle is required to program it. This unit’s default settings are programmed so that it runs from shore power first if it is available, switches to batteries (like a ups) automatically when shore power fails or is absent. It will also supplement shore power with battery power if the incoming power is below voltage spec.

1. You should not turn the batteries off. The inverter is not “inverting” shore power, it’s passing it through via a relay. When you turn off the batteries, the inverter reads no voltage and is trying to “fix” the problem. If you haven’t changed the factory settings, the Multiplus “turns off” the batteries internally when sufficient shore power is available.

2. Your unit must be programmed for your battery type and available amp hours. It’s possible it is cutting off because it thinks (based on settings) it is reaching its battery limit.

3. There are also incoming amperage limit settings, as well as output limits in the programming. The Multiplus is one of the most programming-capable inverter chargers out there. It’s really a marvelous device. That also means that a lot of this can be set wrong or interact in hard-to-trace ways if you don’t put the required time into the manuals, Victron videos and web articles, etc to know what each page of programming does.

4. If you’d like to run things only when shore power is available, and never from batteries, there are connections available on the MP for those, as well.

You’ve got a great unit there! Take the time to make sure you get it set up right, even enlisting help from your dealer or a pro. Set up right, it’ll deliver everything the spec sheet shows.

Thank you for the insight. I will certainly have to adjust the settings as my next move and see if I am still having issues.