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jeanbaptistesegard asked

Voltage ratio of 8 times on MPPT 450/100: error #18

I have a DC source at 393-335 V (a battery) on the In side, and a 48V battery on the Out side (41-52 V).

I have discovered that when the source battery is fully charged and the target battery discharged, the DCDC shows error #18 "charger excessive current". And that there is a limit of 8 time float voltage on the In side.

Is there a way to circumvent this issue, or is it simply that the In can't be 400 V on a 48V battery ? If so, I suggest to make this very clear in the labelling and specsheet of the device, as this info is far from evident. When I read 450V In and 48V out, I take it as granted !...

battery system voltage
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In case you don't believe @Matthias Lange - DE


https://www.victronenergy.com/upload/documents/Datasheet-SmartSolar-MPPT-RS-EN-.pdf

The top two notes are essentially telling you not to use it as you have chosen:


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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

1. It is in the datasheet and the manual.

2. It is not designed to have a Battery on the input because there is also current limit of 18A on the input side.

You are not using the MPPT as intended.

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jeanbaptistesegard answered ·

Thank! The current on the input side remains well below 18A, as we do a careful precharge and we start the converter (and the MPPT) only afer having terminated the precharge (otherwise there would be an inrush indeed).

I still believe the 8 times ratio and voltage range could be made clearer.

Best regards

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Hi @jeanbaptistesegard

Did you read the product manual and the data sheet before buying and installing the MPPT?

How would you suggest this could be made clearer?

It is a novel limitation to Victron MPPTs, and I was responsible for trying to articulate it, so am very open to suggestions for how it could be improved for clarity.


Here is the description of the behaviour in the manual - https://www.victronenergy.com/media/pg/SmartSolar_MPPT_RS/en/installation.html#UUID-a96ec91b-a21c-0536-1a40-278fd7f9410d

@snoobler linked the product datasheet already

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jeanbaptistesegard answered ·

Thanks!

I have a question regarding the manual: on the low side we have a 48V battery with a float voltage (max voltage) of circa 52 V and min voltage circa 40 V.

Our understanding was that the max voltage on the in side is 52*8 = 416 V. So we thought we were OK.

On the in side we so have a max voltage of 400 V and we thought this was OK!

Our source is a battery, and we control the output current via the MPPT.

On this video (https://youtube.com/shorts/nmqQErdXJI4) you see the pb : 393 V in and 43 V out and we get error 18. But we are far from the 52 V float voltage.

Is there a parameter or a firware version which could allow us to operate in current mode and a ratio over 8 ?

Best regards

JB

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