Anyone else here using multiplus 2 48/3000? Question about surge capacity.

[brandonboosted]

I am currently using 2 Victron Multiplus II in a split phase configuration. I have started the workings of being able to back feed my main panel in a power out situation (temporary only). I'm a little over a year into this build and I am almost content with its current state and performance. At first it was just going to be extremely small scale but the more I dug in the more I wanted to scale up the project. That led me to 6.4kw of solar, 42kwh of batteries, and 4.8kw of inverters. Currently this all feeds a dedicated load panel that runs some critical loads and 2 mini splits. I cant really seem to find much information on these inverters being used, they are relatively new, I think they came out in the US around May and I got my hand on a couple right away, at this time I thought 4.8kw would be enough to run what I wanted to run at that time, but I didn't take my surge capacity into equation. My understanding is these are LF inverters and should handle a 2-3x surge, with that being said, has anyone else successfully been able to start their HVAC ac compressor with one of these inverters? I have read some can surge up to 130a and when my clamp meter with inrush shows up ill know for sure what I'm dealing with. I am seeing these LF EG4 and growatt inverters doing it fine and wondering if I should have gone something along the lines of that, I can add 2 more inverters in split phase but that only gets me to about 40A per phase and that would be 120A (x3) for a very small amount of time. Running my hvac is really more of a want than a need, mostly want the ability to run my heat pump if needed, running only pulls like 1000w per leg its all just the startup that I am concerned about. I have tested my 120v air compressor, that is about 44a surge (approx without inrush meter) that seems to be fine. Any help is appreciated, thanks.

 

[sunshine_eggo]

MP2 are simply redesigned MP, which have been around for decades. Most changes were forward looking for code compliance and grid interaction. It's still essentially the same core.

They have a reliable 2X surge for 20 seconds, but I doubt they could start a big HVAC unit. 44A on one leg is above its surge rating, so I'd consider myself lucky on that one.

Most of the EG4 and growatt inverters are HF with negligible surge, so I'd be curious if you could link to evidence showing one of these inverters starting a high surge HVAC unit.

 

[brandonboosted]

MP2 are simply redesigned MP, which have been around for decades. Most changes were forward looking for code compliance and grid interaction. It's still essentially the same core.

They have a reliable 2X surge for 20 seconds, but I doubt they could start a big HVAC unit. 44A on one leg is above its surge rating, so I'd consider myself lucky on that one.

Most of the EG4 and growatt inverters are HF with negligible surge, so I'd be curious if you could link to evidence showing one of these inverters starting a high surge HVAC unit.

I know these aren't UL listed yet which is unfortunate but sounds like a new version of it will be within a year.

Where did you find 2x for 20 seconds? that was while running around 600w on that phase as well I forgot to mention.

Maybe it was just them growatts, Average Joe on youtube used his 12kw growatt LF, and david poz I believe mentioned he ran his and he's using an external transformer I believe with 2 growatts in parallel.

 

[sunshine_eggo]

I know these aren't UL listed yet which is unfortunate but sounds like a new version of it will be within a year.

Where did you find 2x for 20 seconds? that was while running around 600w on that phase as well I forgot to mention.

Maybe it was just them growatts, Average Joe on youtube used his 12kw growatt LF, and david poz I believe mentioned he ran his and he's using an external transformer I believe with 2 growatts in parallel.

IIRC, the 12kW Growatt has a big honking transformer.

I'll try to find the reference.

 

[JoeHam]

Perhaps a soft start could address the problem :

 

[brandonboosted]

I doubt this is accurate but this says the surge is only 4.3. I have looked into those, that may be the route I go especially since it looks like it would be pretty close with the reduction the soft start does. It would suck to do it and still not be able to start it tho.

 

[brandonboosted]

Here you can see the inrush is 51.4 ac amps which is about 1.5x the wattage of the inverter. Occasionally the overload light would flash briefly but voltage stayed stable.

 

[740GLE]

What make and model mini split heat pumps? Most good ones have inverter based compressors so inrush current is very minimal.

Either way if you do decide to upgrade those multipluses hold their value so you should recoup most of you’re cost (as long as you don’t have to ship them).

 

[brandonboosted]

What make and model mini split heat pumps? Most good ones have inverter based compressors so inrush current is very minimal.

Either way if you do decide to upgrade those multipluses hold their value so you should recoup most of you’re cost (as long as you don’t have to ship them).

I should have specified what the inrush was on, whoops. That was on the air compressor as a test. I’m currently running 1 9k 120v cooper and hunter and 1 24k MRCOOL diy full time on this setup, there’s is no surge with the inverter style dc compressor. Only consideration is total wattage pulled at peak. I think if I can get 50a inrush on one then if I add 2 more that gives me 100a surge per leg and should be enough. Either way if I ever want to run my water heater and ANYTHING else I have to add more capacity anyways.

 

[740GLE]

Time for a hybrid hot water heater ?

 

[Lilikoi_Heavy_Industries]

I know these aren't UL listed yet which is unfortunate but sounds like a new version of it will be within a year.

Where did you find 2x for 20 seconds? that was while running around 600w on that phase as well I forgot to mention.

Maybe it was just them growatts, Average Joe on youtube used his 12kw growatt LF, and david poz I believe mentioned he ran his and he's using an external transformer I believe with 2 growatts in parallel.

I have an early multiplus II 48/3000 install also, but no split phase, and usually much smaller loads. It sounds like the 5000W models might fit your build better?

You have high quality equipment that is extremely efficient and reliable right now. Growatt is none of those things in my opinion. Are you paying attention to how much power those inverters waste just to be powered on? (so many youtube videos ignore the huge idle draw of growatt, etc)

I've seen european models of Multiplus 3k's rated for 5500W surge in their official specs, if I remember correctly, but I don't know if I've seen more detail on the model we're running.

 

[brandonboosted]

I have an early multiplus II 48/3000 install also, but no split phase, and usually much smaller loads. It sounds like the 5000W models might fit your build better?

You have high quality equipment that is extremely efficient and reliable right now. Growatt is none of those things in my opinion. Are you paying attention to how much power those inverters waste just to be powered on? (so many youtube videos ignore the huge idle draw of growatt, etc)

I've seen european models of Multiplus 3k's rated for 5500W surge in their official specs, if I remember correctly, but I don't know if I've seen more detail on the model we're running.

After more testing I would agree with you that 5500w is probably the max surge on these. My car lift pulls 52a per leg which is 6200w and the lights dim pretty good for a second.

 

[brandonboosted]

After more testing I would agree with you that 5500w is probably the max surge on these. My car lift pulls 52a per leg which is 6200w and the lights dim pretty good for a second.

Getting a voltage sag to 113 is this any room for concern?

 

[chess-equality]

I'm about to suggest supercapacitors / ultracapacitors but this solution is for batteries, not inverters. The inrush though might also affect the batteries (=BMS).

If it's really the inverter, a soft starter could be used but it will need to be big for a HVAC.

 

[Lilikoi_Heavy_Industries]

View attachment 112366View attachment 112367
Getting a voltage sag to 113 is this any room for concern?

113v at your device sounds okay, but 113 at your distribution could be concerning depending on how much drop there is later in the system. 110v at the device should usually be fine--pros please correct me if I'm off there...

Is there any voltage sag on the DC side which is causing the AC sag? My reliable 3000W 48V has much harder AC sag when the lead acid batteries start getting weak and dropping volts. LED lights dim hard when you start the dryer at 60% SoC... The LiFePO4 batteries take harder discharges down to empty without hesitation, and the AC power is better as a result.

Your battery bank sounds large so it's probably not an issue, just something to check to see if there's an unexpected DC bottleneck, etc? I can't see your wires, check the temps, tighten bolts, etc!

 

[stumped]

Did you determine if your two multis can start your HVAC?

Mirco-Air Easy starts seem to drop inrush amps in most reviews by approximately 66%.

EasyStart™ 368 Soft Starter

The EasyStart™ soft start motor starter supports 115 & 230V A/C motors & employs a 4-part start ramp sequence that offers the lowest possible start-up current.

www.microair.net

 

[brandonboosted]

Did you determine if your two multis can start your HVAC?

Mirco-Air Easy starts seem to drop inrush amps in most reviews by approximately 66%.

EasyStart™ 368 Soft Starter

The EasyStart™ soft start motor starter supports 115 & 230V A/C motors & employs a 4-part start ramp sequence that offers the lowest possible start-up current.

www.microair.net

Have that in my cart, based on my math it should work if the only load I had was the ac but if I was running a mini split and or water heater I'm almost positive it will kick out the inverters, or at the very least create a voltage drop. The plan will be to install one as soon as I get some more wiring stuff done.

 

[Watts Happening]

Your use case, and equipment is stunningly similar to mine. I just posted it. I’ll test out surge capacity soon, but in a real world use I won’t have much surge. Both the trailer, and my house only use mini splits.

The Ultimate Contractor Camper

Howdy everyone! The project I’ve been working on lately is a multifunction trailer. Among my business ventures I do low voltage contracting. I’ve chosen to use a trailer rather than a van for many reasons. This trailer is a 12x7 plus a 2 foot v-nose, 8 foot interior height. Certainly not...

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[sunshine_eggo]

IIRC, the 12kW Growatt has a big honking transformer.

I'll try to find the reference.

Didn't follow up. Was wrong. Not 20 seconds. Depends on if the unit can maintain stable output, can be up to 2 minutes or as little as 1/2 second.

Here's Johannes explaining it:

 

[brandonboosted]

Didn't follow up. Was wrong. Not 20 seconds. Depends on if the unit can maintain stable output, can be up to 2 minutes or as little as 1/2 second.

Here's Johannes explaining it:

Great info, thanks for sharing.