I have a Multiplus-II 48/3000/35-50 120v inverter/charger running on a very small off-grid cabin setup. I plan to use solar to charge the batteries almost all of the time, but in case the batteries get very low, I’d like to be able to use my very small Honda eu1000i gas generator to charge the batteries. The output of the Honda generator is 8A at 120v.
When I go into the settings of the Multiplus in the Cerbo-GX, I am able to set the input current limit to 8A, but when I try to save the setting, it reverts to 9.5A.
-Am I understanding correctly that the Multiplus will attempt to draw a maximum of 9.5A @ 120V with that setting?
-Is the 9.5A minimum charge current some sort of necessary value, or is it arbitrary?
-Is there any way that I can make 8A stick as the value?
If you search for minimum input current limit you’ll see this is a common question. The Multi’s manual indicates the minimum AC input current limit if PowerAssist is enabled. If you want to be able to set a lower AC input current limit just turn off PowerAssist. That has its own implications but could be a solution for you.
This is a very good question! I believe it is a very common problem. I had this same problem until today! I am in a place where the circuit breaker of the AC circuit I am connected to is 4A, and the lowest value that my Multiplus accepts for the AC input limit is 6A! I was managing the problem more or less well by limiting the maximum current of the battery charge, reducing the power of the air conditioning unit and turning off the AC input when I needed to use a higher power appliance, such as the Air Fryer. But this is a very annoying way of managing the problem, and even so the 4A circuit breaker would still trip from time to time. But then I found a solution by reading this topic here in the community and another one about the same problem! The first piece of information, which is essential, is the one given by Ed, above, that the minimum current limit value for the AC input (in my case, 6A) only exists when the PowerAssist function is enabled! And by disabling PowerAssist, it is possible to set lower AC input current limit values, values that will be used by PowerControl! This is information that could be much clearer and more explicit in the Multiplus manual!
Remember, PowerControl is the control of the battery charging current so that the AC input current does not exceed the established limit. And PowerAssist is when the charging current has already been reset by PowerControl and the AC load has exceeded the limit configured for the input current. In this case, the inverter supplements the input current to be able to power the load without exceeding the current limit configured for the AC input. So, by disabling PowerAssist, it is possible to set lower input current limit values (in my case, 4A), and as long as the AC load is consuming less than 4A, everything will work fine, with Multiplus controlling the battery charging current via PowerControl so that it does not exceed 4A at the AC input. The problem is when the AC load exceeds 4A, because now Power Assist is not enabled to keep the AC input below the established current limit. What will happen is that the current drawn from the power grid will rise along with the AC load, without any limit (until the circuit breaker, in my case 4A, trips). But there is a way to get around this problem! It is possible to configure assistants in Multiplus so that it disconnects from the AC input (ignores the AC input) when the AC load exceeds a certain value! This configuration is in watts, not in amperes, so I can configure, for example, so that the AC input is ignored when the AC load exceeds 880W (220V x 4A). This way, the entire AC load will be powered by the inverter, without tripping the 4A circuit breaker of the circuit to which I am connected. When the AC load falls below 880W, I connect it back to the AC input. This way, I can limit the AC input current to 4A, using the maximum available power while the AC load is below the available power limit at the AC input. The only thing that isn’t perfect is that when the load exceeds the input limit, the entire load will be powered by the battery, and the grid power will be discarded. But with Power Assist enabled, it will also not be possible to use the power at the AC input in this situation, because the input circuit breaker will trip! So it’s a solution that’s close to ideal, especially if the situation in which the AC load exceeds the AC input current limit is not very frequent or long-lasting! One bad detail is that this AC load limit setting above which the AC input is ignored is done by VE Configure, that is, it is not easily modifiable, it cannot be modified by GX Touch, for example. So, when the input current is no longer limited to 4A and I modify it on the panel (GX Touch) to a higher value, the AC load value above which the AC input is disconnected will remain the same. But it should be possible to charge the battery with higher currents as long as the AC load does not exceed the value set in the assistants. And if it is not very frequent or long lasting that the AC load exceeds the set limit, it will not be a big problem to disconnect from the AC input even if the load is still below the current input limit.
Everything I am talking about here could be in a Victron document! It is a very useful application for features that are already available, and it makes it possible to bypass a limitation of the device that can be very annoying.
Detalhei melhor a solução que implementei para esse problema nesse outro tópico, onde coloquei um print dos assistentes que criei para contornar o problema: