question

Hello @brucevanderbilt . You have a lot going on with that system and she must be a huge cat. It is hard to attack this so perhaps one issue at a time. Let’s cover the reverse power light on your panel.

The reverse power light is a small light wired between the earth and neutral. The reason is the neutral and earth are joined at various points in the system. Usually the earth and neutral are joined at the distribution board at the Marina. If between the Main distribution board and your boat the the active and neutral we’re somehow reversed, your light would glow because the neutral would now be active.

Ok, let’s assume the active and neutral are not reversed but somehow the light is still glowing… why??

The reason is the cabling and connections between the distribution board and your boat have some voltage drop. Simple ohms law tells us the voltage drop is proportional to current flow. The voltage drop on the neutral line allows a voltage to develop between Neutral and Earth ( no current in the Earth wire). That voltage allows the light to glow. More current ( greater load) makes the light glow brighter.

Sometimes the voltage drop may be caused by a corroded connector on the neutral pin of the connector on the dock or maybe it is simply light cabling supplying the marina pedestals.

I hope that makes sense. The light dimly glowing does not mean the voltage is actually reversed and if the ground relay on a Multiplus is engaged the light would go out because earth and neutral are tied together on the output of the multiplus.

I would not tend to associate that light glowing with the issues you have with your Victron Multipluses.

I hope this is a start.

Hello @brucevanderbilt ...now just trying to attack the next issue. Perhaps the glowing reverse power light could be a hint to what is happening.

It would be helpful to know what the mains voltage is when the multiplus is in "assist mode". If the mains voltage to your vessel drops under moderate load, the multiplus may interprete that as mains requiring assistance, no matter what the current limit is set to. I think if the Multiplus has "Dynamic Current Limit" enabled, the mulitplus will avoid dragging the supply voltage down by "power assisting". The mains issue may be that the mains voltage is sagging under load and the Multiplus is seeing the voltage drop and trying to compensate for it. Turning off "Dynamic Current Limit" may help remove the power assist issue but may induce a low mains voltage alarm. That would be a good experiment.

I hope this helps.

Hello @brucevanderbilt ...Just dealing with the generator issue, are you saying the ELCI trips causing a loss of power? In other words it trips and power is lost so if you remove it (bypass it) power is restored and all if good. If that is the case can we characterise the generator problem as the ELCI keeps tripping or have I misread that?

Hi @Trevor Bird. I very much appreciate the methodical and thoughtful approach to this issue. Thank you!

It's worth noting that I installed the system myself (after my many months and iterations of schematics and planning reviews with my local ABYC tech). I built a mock-up of the space in my garage and tested everything thoroughly prior to installing in the boat. My ABYC tech has said that it’s one of the cleanest and robustly built installs he’s seen. We’ve had several months of flawless performance in the boat through the spring.

With this being my only Victron install experience, I don’t have the deep fundamental expertise to troubleshoot all anomalies. So your approach is incredibly valuable. I'll work my way through your 3 comments here.

1) Your explanation of the polarity light is helpful to conceptually understand how it works and what to infer from it's behavior. I had my local ABYC tech look at it and his thought was that the glow was so minor it's indicative of normal voltage drop. I haven't had him go through the whole system because a) they do not typically work with Victron products b) we are preparing for a circumnavigation, and I need to be able to understand how to troubleshoot the system myself.

2) The lowest I’ve seen is 114v on shower power, and never less than 119v on genset. It’s an older marina, quite full, and probably a lot of air con units running at night. My pedestal only has a 30amp connection, and I have my input limit typically set at 25amps. But I will keep a closer eye on this. My panel has a large digital display for shore power voltage and also voltage at the main panel (side by side). So it’s easy to notice any fluctuations.

I just looked in my latest VE Config file and my configuration has the “Dynamic Current Limit” unchecked. But this give’s me much food for thought. Could there be something to do with the boost factor? Or UPS setting? Please take a look at my settings and let me know your thoughts.

3) The ELCI has NOT tripped coming out of my Genset nor the one on shore power. It appears the generator is performing well as voltage holds 120 up to max load and runs all onboard equipment flawlessly when bypassing the Multipluses.

My ABYC tech mentioned that it’s possible that the ELCI is introducing some stray voltage that is interfering with the Multipluses. On his recommendation, I removed it and sure enough, it appears the system is accepting generator power without issue now (but I need to verify this under full loads still). So it leaves me wondering if the ELCI breaker could be bad? Or if there’s some other intermittent problem related to the shore power issue that I’m missing and thrown off by coincidence of removing the ELCI breaker. Or does Victron equipment not play well with ELCIs possibly?

It just occurred to me I could try swapping the shore power ELCI breaker and see if I get different results. Ultimately, I want to keep the ELCI in the system to meet ABYC code.

Hello @Trevor Bird,

I've put my system through it's paces for the past couple months since my last update on this thread. The system is now accepting AC input from both shore power and my generator with 100% reliability. Unchecking the UPS function on my Multiplus Configuration was the key. Thank you for that recommendation!

I'm still consistently experiencing a strange power assist behavior. When my loads exceed my set input limit, the AC input drops to well below the input limit set and stays there. The net result is that I continue to experience batteries that are drawn down in the morning after running a couple air conditioners that cycle on and off through the night. Once the load exceeds the input limit, the input power drops and from that point forward stays at the lower input.

In the attached video, I have the input limit set to 20amps. The system properly accepts the roughly 2400 watts of input power and easily handles the load of one airconditioner of 1700watts while also charging the batteries with the balance of power remaining. When I power on the second airconditioner, the load increases to slightly above the input limit and the system reduces the input to roughly 1600 watts. Because the system reduces the input power, it then starts to tax the batteries for the difference of power needed.

If the system continued to accept the full power up to the set limit, the input power would mostly cover the loads. This behavior is consistent when exceeding any limit I set and regardless of the type of loads I use (microwave, oven, Air Con, heat guns, etc). It also consistently behaves this way whether my source power is shore or generator.