# question

## MPPT 75/15 current question.

On my VictronConnect display there are two values for current. Solar current and battery current.

At the moment, it is overcast and my 100 watt solar panel is shown in the display as producing 19 watts

Solar current is shown as 1.1A and Battery current is shown as 1.4A.

I assume the Solar current refers to the current produced by the solar panel but why is the battery current a different figure?

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Hi Snapster. It's only because your solar is working with a different V.

Pv// 19W / 1.1A = 17.3V (It has to be up at least there somewhere for it to work at all)

Batt// Assuming 100% efficiency (won't be). 19W / 1.4A = 13.6V (typical for a batt under charge)

Expecting high accuracy at such low W is a big call too. Must be pretty poor weather, but what you see is normal. If you 'series'd up' a couple of those panels the difference would be much greater.

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This is how MPPT works. Basically, the PV is on one circuit, then there is a power converter, then the battery is on another circuit.
You will also notice that the PV Voltage is different from the battery Voltage. Your PV Voltage was probably saying something like 17V or 18V right?
When you multiply the Amps and the Volts on each side, you get the power. It is the power that will be very close, I can guess that your battery Voltage was about 13.5V at that time?

Your charge controller can take up to 75V at the PV side. Imagine the PV was at 60V and 2A, then your battery will be charging at anout 9A when it is 13.5V

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Thanks both, that all makes sense to me now.

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