MPPT 110/20 Smartsolar and Smart Shunt showing different readings?

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David asked Jun 30, '22

MPPT 110/20 Smartsolar and Smart Shunt showing different readings?

Hi

I have had a Victron Smart Shunt installed for sometime in our campervan and I have recently upgraded the old solar charger to a MPPT 100/20 Smart Solar.

I have linked them on a VE network via the Bluetooth and the network shows that I am getting the External Battery current sense and External Battery Voltage sense from the Smart Shunt.

I would assume that the current and voltages figures would be the same at the same time but i have attached 2 screen shots taken at the same time below. ( I used my phone for the Smart Shunt and an iPad for the Smart Solar)

and below is the Smart Solar reading at exactly the same time

If they are on the VE network and the Smart Solar is getting the Voltage and Current from the Smart shunt they would be the same?

Also why is the Solar Current is 2.0A but it shows the battery Current is 2.8A.

any help would be great

Thanks in advance

smart solar set-up help

img-8221.png (91.2 KiB)

img-1522.png (189.3 KiB)

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Answer 1 · 2022-06-30T20:57:08Z

klim8skeptic answered · Jun 30, 2022 at 08:57 PM

The battery voltage is the same in both screenshots. Thats ok.

The current will be different as the devices are displaying different operations.

The mppt displays charging current going to the battery (and loads).

The smartshunt displays current going into and out of the battery.

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Answer 2 · 2022-07-01T06:51:19Z

David answered · Jul 01, 2022 at 06:51 AM

Thanks for the reply.

Im still not sure why the MPPT can have a Solar Current of 2.0A and a Battery current of 2.8A. How can that be higher.

The operation manual says that the Solar Current is the current flowing from the PV array into the solar charger and the Battery Current is the current flowing from the solar charger into or out of the battery.

Where does it get the extra 0.8A from ?

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Answer 3 · 2022-07-01T08:29:14Z

jc2010 answered · Jul 01, 2022 at 08:29 AM

The MPPT is essentially a DC-DC converter, those extra 0.8A come from converting the extra voltage supplied by the panels into extra current at a reduced voltage to the battery.

PV -> 17.13V 2.0A -> MPPT -> 12.53V 2.8A -> Battery

It is taking the ratio of more voltage and less current and converting it into less voltage and more current.

17.13 V * 2.0 A = 34.26 W
12.53 v * 2.8 A = 35.08 W

There are momentary spikes and the data will not be 100% accurate but as you can see its approximately the same amount of energy in and out ~35 W.

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Answer 4 · 2022-07-01T08:59:34Z

David answered · Jul 01, 2022 at 08:59 AM

Thank you jc2010 for the explanation

it is much appreciated

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