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offgridcircuits asked

Turn Multiplus Charger on/off Without MK-3

I have a Multiplus II 2X 120 and a cerbo. I can turn the charge function of the Multiplus off from the MK3 programmer. Is there anyway to turn the charge function on/off without the MK3? I'm not talking about the panel switch. For instance, if shore or generator is on and the inverter is passing through, I do not want to charge the batteries or sometimes I do.

Multiplus-II
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2 Answers
Alexandra avatar image
Alexandra answered ·

@offgridcircuits

What batteries do you have?

You should be able to set the charge current to zero through DVCC.

If not there are some options in node red.

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offgridcircuits avatar image offgridcircuits commented ·
I have Lithium batteries. They have an internal BMS. These are home built LiFePO4 Packs. They work exceptionally well. The reason is that I want to turn off and on the charger is I have another inverter working as shore power and with power assist, I get more AC output from my system, so I can run about up to 4K Watts. My single Multiplus would go into overload or in warm weather, temperature warning when my loads go too high. This solved the problem. But now, I want to run the generator through the system and turn the charging back on. Can you point me towards "node red"? I'm not sure what that is.
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derrick thomas avatar image derrick thomas offgridcircuits commented ·
Node red is a node based programming system included with Venus os large. Install the large os version, then enable node red in the cerbo settings. You then have access to many additional features which you can Taylor to your needs.
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Alexandra avatar image Alexandra ♦ derrick thomas commented ·
Also with node red don't start there. Its a steep learning curve.

There is the option of the charge current control assistant, but you will need to be able to have a variable voltage between 1v and 4v this will alter the charge current according to the assistant set up. And then connect it to the aux or temp connections depending on programming there as well. You will need ve config and the mk3 as well.


And then try the DVCC charge current on the GX. Way simpler and user interactive.

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derrick thomas avatar image derrick thomas Alexandra ♦ commented ·
Agreed, there is a bit of a learning curve with node red, but which option is best (DVCC or node red) could depend on if there are mppt's in the system. Limiting CC to zero in DVCC is also going to disable MPPT charging. Using the new custom nodes in node red or mqtt you can change the CC in the multi without effecting the mppt's.
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offgridcircuits avatar image offgridcircuits derrick thomas commented ·
I was looking for a simple solution and not one where I had to go to MIT for a degree.
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w8dev avatar image
w8dev answered ·

Not sure if this is what you're looking for but I have a pair of Multiplus-2 5kVA inverters and I programmed one of the cerbo relays to control whether or not my inverters charge from the grid when I'm on AC in power.

I'm using the Charge Current Control assistant and I have a CAT cable running between Relay 2 on the Cerbo and the Aux Input 2 on the primary Multiplus.

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The charge value is hard-coded in the assistant, but I can turn it on/off through the cerbo.

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