I have a 3000va MP-II with the Split-Phase 2x120v version, and I’ve had some incredibly hot days recently where my little 2000w Geny can’t supply enough power to run the constant run A/C and other loads fully, so it’s constantly in Assisting mode which is continuously running down the battery bank.
So I got to thinking, why couldn’t I run a second (not identical) Geny into the L2 of AC-In-One and wire the L2-Geny’s Neutral into the same neutral that’s used with L1. These 2 Geny’s would NOT be perfectly In-Phase or Opposite Phase but probably will be varying continuously. Plan would be to move my Air/Conditioner over to the L2 of AC-Out-One so that one Geny will power the A/C only and the other would power everything else and batt charging. Normally the MP-II will combine L1 & L2 AC-OUT when on Inverter or when only L1 is bringing in power - so that’s perfect also.
On one possibly naive hand I don’t see why this couldn’t work. But on the other, my pessimistic brain is saying that I’m obviously missing something and this couldn’t possibly work. SO, I’m asking all you smart people! I don’t want to fry anything if I don’t have to. If you have a safety reason, please be specific so that I can understand the factual issues.
THANK YOU!
I can’t comment if the MPII would accept the second gen on the L2 input, but i do know that most inverter generators can be paralleled together. It might be a simpler solution?
No, because the inverter synchronizes to the input.
Both generators [edited] would have to be synchronised in wave form for it to work. And that is not likely in a regular set up. So the inverter really is not designed to do so.
If you really need to charge and run loads and there is some kind of limit, use one for charging and have a bypass for the other to run loads.
No sure I understand a few things:
A: Sentence 1: Are you talking about the MP-II’s inverter synchronizing to the L1 Input? Does it also somehow try to syn to L2?? I’m not sure how since there’s only one inverter.
B: Sentence 2: 'Both inverters would" - there is only one inverter in this MP-II. Please rephrase?
C: Sentence 3: Could you please clarify this? Are you suggesting buying an additional charger?
THANK YOU!!!
My apologies. Thought wrangling this morning was not successful. Edited.
Short version, the inverter can only synchronise to one source.
Thank you for trying to help me.
I’m still not grasping what you are trying to say. Normally, this Inverter would receive two legs of 120v split phase power - so L1 & L2 would be coming in in opposite phase - so that means that it can only synchronize to one of those waveforms (L1), right? How can the single Victron Inverter synchronize to both waveforms (phase angle..?) in “normal” operation? Perhaps I am not grasping exactly what ‘synchronize’ means in this situation?
I would appreciate the “long” version of any explanation - Thank you!!
A better question might be ‘why would the lone MP-II 2x120v synchronize with L2 at all?’ All it does is either A) Pass it through to AC-OUT-1 L2 (if sensed coming in), OR, B) Cuts it off and connects L1 & L2 Outputs for Inverter Mode or Single-Phase (ie L1 only) Input Modes - so saying the single lone Inverter needs to Synchronize with L1 AND L2 makes no sense to me.
If you or anyone could explain that I would Greatly Appreciate it! Thanks. Shawn
The 2x120 when connected to split phase input synchronizes the ‘inverter’ to L1 only, L2 is simply passed straight thru. Only L1 is ‘connected’ to the inverter circuitry for power assist or charging. L2 is just passed straight thru, no power assist, no charging. When connected to single phase input, L2 input is ignored and L1 and L2 outputs are bonded, providing power assist to both L1 and L2 outputs.
Yes!! THANK YOU Derrick!!
Your explanation is exactly as I know it - and so my question stemmed from that.. could I not run a completely separate source of 120v into the AC-OUT-1-L2, after commonizing the neutrals? No-one has fully and properly answered this main question yet.
So, Anyone - can anyone answer the original question? Because it has not truly or fully been touched yet. PLEASE - someone must know.
Please and thank you! Shawn
That would be a bad idea, use the AC input instead
Disclaimer, im also used to 50Hz, never worked with splitphase, never saw a 2x120 MP
You are looking to add another 120V source, but are aware that this will not necessarely create 240V in the end. If the sinewaves of each Genset match, then there will be (theoretically) 0V between L1 and L2. If they happen to oppose eachother by 180° then you will see the full 240V. But anything inbetween is possible since the gensets are not electrically or mechanically synchronised to eachother.
So you will have two 120V phases but no 240V. I would disconnect any 240V load.
Looking at the schematic, i think the 2x120 is a regular 120V Multiplus with an additional transfer switch internally.
The circled relays could be a simple transfer switch, while the rest is a regular 120V MP, with a double pole AC out 2 relay. If thats the case, then your idea could work.
Of course it could be more complicated, there could be a second set of AC in measurments added for L2 with the circled relays also controlled by the MP2s circuitry. Is there any metric available of L2? In VictronConnect or VRM, do you see any voltage or current measured on L2?
“could I not run a completely separate source of 120v into the AC-OUT-1-L2, after commonizing the neutrals”
Simple answer, NO.
Explanation: When a single phase source is connected to the ac input, L1 and L2 outputs are bonded in order to supply 120v to both L1 and L2 of the output side. This is the main benefit of the 2x120 over the standard single 120 inverter, to supply both sides of a split phase panel when only a single phase source is available, thereby providing power assist to both sides of the panel when operating from a lower output single phase shore connection.
If your goal is to be able to use 2 generators simultaneously, you have a few options. With a single inverter, the only option is to connect the inverter to 1 leg of the panel, and supply the other leg directly from a second generator. The only other option with a single inverter is going to be 2 generators in tandem that are designed to be paired in tandem. (Think honda for example)
You could use 2 inverters, one for each leg of the panel NOT configured for split phase, with a generator connected to each inverter. I would NOT recommend this method however. This is not Victron approved or recommended, and would require very specific setup guidelines not for most people’s skill level.
None of the options above would provide 240v. If you need 240v but only have 120v generators available, you would need to use 2 inverters configured for split phase with switch as group disabled, or a single inverter and a auto transformer.