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josecokem avatar image
josecokem asked

Max AC Grid charge Watts

This question could be ridiculous for some users but I am not able to find the max watts I can put into the battery from the grid using the multiplus II 3000va 48V AC charger. The datasheet is so confusing and also people talks about amps but is not clear if there are DC amps at 48V or AC amps at 230V. At the moment I think the max power I can send into the batteries from the AC Grid is constant 1650 W until the battery gets full or heat or some other programed limits, but I am really not sure, could any one put the number in watts?

Multiplus-IIbattery chargingcharger
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Alexandra avatar image
Alexandra answered ·

@josecokem

If you look at the whole model number of your inverter, the DC charge amps are there. Usually the numbers on the end are DC AC. So 48/3000/35 32. Is a 48v 3kva 35A DC charge 32a transfer.

The watts now (excluding derating both for heat and voltage etc) is battery voltage X those amps.

I think the 48v 3kVa can do 35A?

So 35 X 48 v 1680 W. But if your battery is at 51.2v nominal it will charge higher at 1792w.

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josecokem avatar image josecokem commented ·
Yes but also the manual says I can discharge the battery at 2400w constant (minus heat limits etc..) So I really do not understand this complicated nomenclature. So this means that at max I can charge the batteries from the grid at 1600W-1700W approx. limit but can send 2400W to my house consumption with peaks of 5000W, is that correct?
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nickdb avatar image nickdb ♦♦ josecokem commented ·
The inverter can invert at 2400W max, AC, unlike DC is constant Voltage.

Batteries voltage varies from model to model and under states of charge, so specifying a charge power is useless.

It is specced to provide a charge current at any given voltage, that is also how battery specs work.


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Alexandra avatar image Alexandra ♦ nickdb ♦♦ commented ·

Everything is amps based as mentioned voltage is not constant ever....

Grid can be anywhere between 180v and 275v so just the 32a transfer can be 5760w up to 8800w....(if it is not getting too hot.)

Then there is cable sizing and resistance also affecting everything.. yay electrical engineering.

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josecokem avatar image josecokem commented ·

If I build a battery with 60V, this means that the Victron will be able to AC charge it at 2000W???

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nickdb avatar image nickdb ♦♦ josecokem commented ·
That would exceed the max voltage specs of 57.6V

Also assumes 25C internal temperature.

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josecokem avatar image josecokem nickdb ♦♦ commented ·
So this would mean I could build max voltage of the battery at 57v, then the max charge would be 1995 W if the battery is at 57v or for example or 1855 if is at 53v, is that correct? Depending on the temp of course.
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nickdb avatar image nickdb ♦♦ josecokem commented ·
Correct. And obviously subject to any other loads.
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