question

aussiedreamland avatar image
aussiedreamland asked

Defining seperate charging currents for MPPT & MP2

Hi there;

I have just added a Plyontech US2000C (total of 3 now) and I want to charge them with 75A.

I have a MP2 GX-Version that can charge with 35A, a Victron Smartsolar 250/60 MPPT attached to 4KW of solar and a solar inverter parallel to the MP with 2KW of solar attached.

At the moment the charge current in the MPPT is still set to 50A, which was ok for the two US2000C, but now I'd like to charge the three US2000C with 75A....BUT, I don't want the MPPT to charge with more than 50A since it already gets pretty hot at times.

As far as I understand, it should be possible that 50A come from the MPPT and the rest (25A) will come from the MP if enough solar energie is present.

At the moment the system (MPPT & MP) only charges with a max. of 50A.

Funny enough that if there's not enough solar energy, the MPPT & MP charger work together to achieve the 50A but won't exceed that current.

So how can I set the system to charge at 75A???

Multiplus-IIbattery chargingsmart mpptcharge current limit
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2 Answers
nickdb avatar image
nickdb answered ·

I presume you're running with ESS? In which case charging will come from solar alone unless you exceed your minimum SOC or choose a different mode for ESS.

The MPPT will derate with temperature so you can just leave it, but if you really want to limit it, setting the charge current directly on the MPPT will cap what it can do.

If nothing is complaining, I would just let the system do what it is designed to do.

MPPT's get quite warm, that is normal.


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aussiedreamland avatar image
aussiedreamland answered ·

My problem is that the system is only charging with max. 50A although there is enough solar energy to charge at 75A.

The only limitation I set is in the MPPT (50A), on the Multiplus 2 the max. current on the charger is set to 35A.

So why doesn't the system charge with 75A instead of just 50A?

The BMS is also showing a max. possible charging current of 75A, so what settings do I have to change in order to charge with 75A?

I don't think changing the max. current in the MPPT back to 60A is going to enable charging at 75A, it'll probably only allow the 60A max.

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nickdb avatar image nickdb ♦ commented ·
In an ESS the multi won't charge at all, only solar is used, unless you set it to keep batteries charged.

The mppt is limited to 50A by your setting so that's what you will get.

The 35A only applies to the multis charger if it is allowed to charge, which it won't do unless you change ESS modes or the SOC is beneath the minimum SOC set.


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aussiedreamland avatar image aussiedreamland nickdb ♦ commented ·
I understand what you're saying, but my system also has a solar-inverter parallel to the MP2 which basically just feeds into the grid.

In addition to the charging current coming from the MPPT, the MP2 also uses the surplus of the solar-inverter to charge the Battery, but only to the 50A limit.

For example: 30A are coming from the MPPT & 20A are coming from the solar-inverter via the MP2 charger.

So if I understand correctly, the max. charging current is defined by the 50A that I've set as a max. in the MPPT, correct?

If that's the case, it would be pretty stupid, since that would mean that I can't use the excess energy from the solar-inverter to charge my battery with more than 50A!

Is there any way that I can get to 75A charging current if enough solar energy (MPPT & solar-inverter) is present, or do I really have to buy a bigger MPPT to do the job?


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ponzoa avatar image ponzoa aussiedreamland commented ·
If your PV inverter is parallel to the MP2, it would need a meter to be able to tell the MP2 that the energy is solar and that it can take it. If single phase, you can use an ET112. Without this, the MP2 will treat it as energy from the grid.


AC Copupling is a different setup but I understood you mentioned it's in parallel.

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aussiedreamland avatar image aussiedreamland ponzoa commented ·
I have an EM24 installed, so the MP knows when there's extra energy coming from the external inverter and that works fine.

For example, there are 35A coming from the MPPT and 15A coming from the MP charger.

But as mentioned, the total limit is 50A and I don't know how to change this to 75A.

Sure I can set the MPPT to full power (60A) but then system (MPPT & MP charger) would only charge at a max. of 60A instead of the 75A that the Plyontechs are allowing.

So what am I missing here?


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klim8skeptic avatar image klim8skeptic ♦ aussiedreamland commented ·
You have re written your OP.


Do you expect contiguous advice given that the OP has now been munted?

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