Advanced Multiplus: Assisting too soon

[daleyocum]

I consider myself an advanced Victron user but this one has me stumped.

My Multiplus / Cerbo seems to be interested in showing off and insists upon assisting my AC system before it needs to or it doesn’t draw the full amount from shore that I told it to. I suspect there’s a setting somewhere buried in the menus but I haven’t been able to find it.

The screen attached is one example where the multicontrol is set to 30amps max of shore power (we’re plugged into 30a right now) and is set to “Inverter.” Note that the loads are 3501w, which should be about the max for a 30a system, but it’s only drawing 2945w from the shore and making up the rest from the battery and solar. The question is why? Shouldn’t it draw 30a from shore before tapping the battery?

This is especially a problem when we are running our AC on generator as it will draw the batteries down for no good reason. I have an Easystart and the AC draws less than the generator can provide yet the batteries keep getting slowly depleted.

It seems to start this behavior of under utilizing shore power around 2,500 watts coming from shore.

When the multicontrol is set to “charge only” everything works as you’d expect because the inverter doesn’t try to assist.

[goldenchase]

Originally Posted by daleyocum

I consider myself an advanced Victron user but this one has me stumped.

My Multiplus / Cerbo seems to be interested in showing off and insists upon assisting my AC system before it needs to or it doesn’t draw the full amount from shore that I told it to. I suspect there’s a setting somewhere buried in the menus but I haven’t been able to find it.

The screen attached is one example where the multicontrol is set to 30amps max of shore power (we’re plugged into 30a right now) and is set to “Inverter.” Note that the loads are 3501w, which should be about the max for a 30a system, but it’s only drawing 2945w from the shore and making up the rest from the battery and solar. The question is why? Shouldn’t it draw 30a from shore before tapping the battery?

This is especially a problem when we are running our AC on generator as it will draw the batteries down for no good reason. I have an Easystart and the AC draws less than the generator can provide yet the batteries keep getting slowly depleted.

It seems to start this behavior of under utilizing shore power around 2,500 watts coming from shore.

When the multicontrol is set to “charge only” everything works as you’d expect because the inverter doesn’t try to assist.

I am a rookie Multiplus user but I will take a shot. Since you are plugged into a 30 amp shore power source only one leg is active on your two leg 50 amp system. So the Multiplus is going into the PowerAssist mode to try to make a 50 amp system. Here is a post were I was trying to figure it out.

Most of my experience is in running a two leg 30 amp shore power connection to the Ford Propower Onboard Generator.

[richard5933]

Mine did the same thing on my coach. I was told it was because breakers will begin to trip as low as 80% of their rated capacity, especially if a device starts up when near the max load.

The alternative is for the inverter to wait until max is reached, in which case a weak breaker or heavy start up load could create a problem. I left mine to err on the side of caution.

[daleyocum]

Originally Posted by goldenchase

I am a rookie Multiplus user but I will take a shot. Since you are plugged into a 30 amp shore power source only one leg is active on your two leg 50 amp system. So the Multiplus is going into the PowerAssist mode to try to make a 50 amp system. Here is a post were I was trying to figure it out.

Most of my experience is in running a two leg 30 amp shore power connection to the Ford Propower Onboard Generator.

In my case I just have single leg 30 amp service, not as fancy as your amazing system.

[daleyocum]

Originally Posted by richard5933

Mine did the same thing on my coach. I was told it was because breakers will begin to trip as low as 80% of their rated capacity, especially if a device starts up when near the max load.

The alternative is for the inverter to wait until max is reached, in which case a weak breaker or heavy start up load could create a problem. I left mine to err on the side of caution.

Interesting. I suppose I could change the max setting on the multicontrol to allow it to go above 30 and see if that solves it. I was hoping there was some other setting I had overlooked.

[57Vintage]

Knowing your background from following your posts for years, I almost hate to ask. Are you sure the power/loads shown on the screen are accurate? I don't recall which type of batteries you have, but is 13.2 volts at 100%?

[daleyocum]

Originally Posted by 57Vintage

Knowing your background from following your posts for years, I almost hate to ask. Are you sure the power/loads shown on the screen are accurate? I don't recall which type of batteries you have, but is 13.2 volts at 100%?

We have 500ah of Battleborn Lithium. I guess I was assuming the Victron display was accurate but thanks for the suggestion. I just checked on the surge protector plugged into the power pole and it claims the same amount of current so I guess I’ll believe the display for now.

So a corollary to this mystery is what’s happening now. We have our Breville electric convection oven running and it turns it’s heating elements on and off like you’d expect to hold a constant temperature, drawing 1,290 watts when on. I have the Victron multicontrol switch set to Inverter just for fun even though the total draw of the trailer is less than half the 30amps I’ve told it to consume if need be.

Now for the weirdness. Whenever the oven pulses on to maintain temperature, the Multiplus assists for a fraction of a second! Sure, this is a first world problem but there is clearly something I don’t understand about when the Multiplus decides to assist. Is it kicking on the inverter whenever it sees a spike in current just to be ready?

[daleyocum]

I think I may have found this obscure setting. I can’t mess with it while traveling because I don’t have a MK3 adapter with me but it’s evidently a configuration setting on the Multiplus to allow for slow starting generators set to Econo mode. Here’s what the manual said.

“ 10.1.4. Dynamic current limit

Setting for use with ‘small’ generator - If an inverter-generator is used, such as the HONDA EU series, the shore current setting will be dynamically reduced (following a period of low current consumption) to compensate for the engine reaction time when higher loads are activated.”

This is from this manual https://www.victronenergy.com/media/...-settings.html. 10.1.4

Since I only use my Honda generator when solar isn’t sufficient and then not in Eco mode, I may try turning this off.

It’s not easy to turn on and off as best I can tell unless someone can show me otherwise. I seems to need the Mk3 dongle and a computer with a direct connection to the Multiplus.

[richard5933]

Good that you found it. Does it really cause any problems when left as it currently is? Yes, you'll momentarily draw down the batteries, but within a few minutes the system should replenish the charge and carry on as normal.

Might be easier to just leave it as is for now and not worry about it.

[jnm30327]

You do not need the MK3 . You can adjust all the settings by connecting through the Victron VRM. You download all the settings to a file using Remote VeConfigure at bottom of Device List. Open the file with the Victron VEConfigure app and save the new adjustments to a file. Then upload the adjusted file back to the Multiplus. You can even do it from home.

[daleyocum]

Originally Posted by jnm30327

You do not need the MK3 . You can adjust all the settings by connecting through the Victron VRM. You download all the settings to a file using Remote VeConfigure at bottom of Device List. Open the file with the Victron VEConfigure app and save the new adjustments to a file. Then upload the adjusted file back to the Multiplus. You can even do it from home.

Wow, not that that’s geeky at all! I’ll still have to try that at home since I don’t have a PC with me. That is handier than messing around with the flakey MK3.

I wish Victron would get the Multiplus integrated with Victron Connect!

[daleyocum]

Originally Posted by richard5933

Good that you found it. Does it really cause any problems when left as it currently is? Yes, you'll momentarily draw down the batteries, but within a few minutes the system should replenish the charge and carry on as normal.

Might be easier to just leave it as is for now and not worry about it.

In thinking about it I’m not sure that will address the issue I started this thread with of assisting too soon. It will fix the little pulsing behavior. That one isn’t, as you say, a big deal. It’s slightly annoying because, with the Victron under my twin bed, I can hear it turn on and off frequently. I’m more interested to see if that switch has any affect on the too-son-assisting issue.

[link2dks]

Following

Dave S

[Life is a Highway]

We are new Victron install owners. The unit was professionally installed buy a famous Victron installer. We were shocked after the install to find out no Victron tech support number. Go to your builder?

All I can say is our new system does the same when it plugged in to our storage units 30 amp service with the 30-50 adapter. I thought it was normal? Don’t know

We do not have enough road time to help further.

[richard5933]

There is a steep learning curve on the Victron systems once you get into the weeds of the menu settings. Fortunately there are some great information pages out there on the Victron Community and other websites.

At one point I did find a tech support number for Victron, but when I checked today was unable to find it again. I remember that it was deeply hidden inside their website.

[Life is a Highway]

That number or customer concern form takes one down the dangerous rabbit hole of death. if the installer accepts it and figures it’s just a part failure your all good if you word it wrong and they take it as a insult to their build you are a outcast left to fend for yourself. Victron has really dropped the ball with no support.

Originally Posted by richard5933

There is a steep learning curve on the Victron systems once you get into the weeds of the menu settings. Fortunately there are some great information pages out there on the Victron Community and other websites.

At one point I did find a tech support number for Victron, but when I checked today was unable to find it again. I remember that it was deeply hidden inside their website.

[vanderwielen]

Originally Posted by daleyocum

I consider myself an advanced Victron user but this one has me stumped.

My Multiplus / Cerbo seems to be interested in showing off and insists upon assisting my AC system before it needs to or it doesn’t draw the full amount from shore that I told it to. I suspect there’s a setting somewhere buried in the menus but I haven’t been able to find it.

The screen attached is one example where the multicontrol is set to 30amps max of shore power (we’re plugged into 30a right now) and is set to “Inverter.” Note that the loads are 3501w, which should be about the max for a 30a system, but it’s only drawing 2945w from the shore and making up the rest from the battery and solar. The question is why? Shouldn’t it draw 30a from shore before tapping the battery?

This is especially a problem when we are running our AC on generator as it will draw the batteries down for no good reason. I have an Easystart and the AC draws less than the generator can provide yet the batteries keep getting slowly depleted.

It seems to start this behavior of under utilizing shore power around 2,500 watts coming from shore.

When the multicontrol is set to “charge only” everything works as you’d expect because the inverter doesn’t try to assist.

went down a rabbit hole with your issue. the MP is rated at 3KVA or 2.4KW maximum continuous output. it would appear you're in excess of this. what is unclear from the documentation from victron is how long assist will be provided when the system is overloaded. so, it would appear the grid is providing 3KW, (i assume, not KVA) and the batteries are providing the remainder, Isn't the MP doing what it should? BTW, I install these and have never placed a load this great, continuously, on an MP, so this is new to me.

[Nishad]

Check your units. 3000VA is about 2400 Watts with a power factor of 0.8 which i think is typical for inductive loads (AC, refer, etc.) So, you might be legitimately getting into assist mode.

My solution is to put the Multiplus II into charger only mode + PassThru via an Victron assistant. If I don't set the PassThru, the MP II tries to charge when the compressor of the AC is off and trips the generation when it comes back up again because the generator cannot respond to the load instantaneously.

Finally, check this thread out. It might help.

https://community.victronenergy.com/...-mutiplus.html

[waninae39]

inductive loads effect what is seen and the difference between W and VA

with a PF=1, W=VA
as the inductive load % increased, reactive currents causes the W and VA to differ and reduce the effective real load capability

this is a tricky topic for novices and often hard to understand as there is real and imaginary current involved. That is why large machines have a PF rating so that the real power consumption figures can be determined

[daleyocum]

It may be my misunderstanding of how the Multiplus works. I was assuming that it was passing through all the shore power available to it and only assisting when the demand exceeds the supply. In the case of my screenshot at the beginning of this thread, those are resistive loads (space heater and electric hot water heater.)

Yes, everything works like you’d expect on charge only.