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scoraigwind avatar image
scoraigwind asked

Correct sequence to power up MPPT controllers

I am wondering how important is it to always connect the battery first when powering up/down an MPPT controller? Seems more important than I had first thought. The manual does say (in the installation section) to connect the battery first, which I understood was so that it can automatically detect 12/24/48V battery, and set its set-points accordingly. I understood that this was needed during the first power up only, and I assumed that after that it would not matter whether you disconnect the battery before the solar, or reconnect it after the solar is connected. This is not made fully clear, as the manual does not specify the correct sequence for normal operation explicitly.

A customer of mine disconnected the battery while the solar was working. Later he reconnected it, (solar still on) and the controller was damaged. Victron did not cover this damage under their 5 year warranty. They said it was clear from the manual that you should not do this. I will need to read the manual again but I wonder how many people know this? I wonder how many people take care to always check that the solar is not connected when they connect the battery after some temporary down time. Seems like people need to know this.

MPPT Controllers
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3 Answers
nickdb avatar image
nickdb answered ·

It is a good idea for initial setup, though you can set it manually easily enough.

After that, it doesn't matter.

On a system restart after a complete poweroff, powering mppts first, before the battery, is an easy way to precharge the inverters, then powering the battery second.


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Fideri avatar image Fideri commented ·
That's my understanding, so I'm surprised at @scoraigwind outcome.

F.

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nickdb avatar image nickdb ♦♦ Fideri commented ·

The issue here is disconnecting the charger while it is generating power.

The subsequent spike could damage the charger, not to mention the nice spark when the fuses are pulled out.

Always drop PV first on shutdown, and power PV last.

For Precharging, the charger is connected to the DC bus. While batteries may be off, there are still "loads" and PV won't ramp more than is required.

This has nothing to do with the initial detection of the battery voltage, but more to do with abusing the poor charger.


6.5. Shutdown and restart procedure

The solar charger is always active when the PV and/or the battery terminals are powered. The solar charger does not have an on/off switch.

To shut down the solar charger, perform these steps in the prescribed order:

  1. Disconnect the PV supply to the solar charger by switching the PV supply off or by removing the external fuse(s) or circuit breaker(s).

  2. Disconnect the battery supply to the solar charger by switching the battery supply off or by removing the exterenal fuse(s) or circuit breaker(s).

To restart the solar charger after it was shutdown, perform these steps in the prescribed order:

  1. Connect the battery supply to the solar charger by switching the battery supply on or by inserting the external fuse(s) or circuit breaker(s).

  2. Reconnect the PV supply to the solar charger by switching the PV supply on or by inserting the external fuse(s) or circuit breakers(s).


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onrbikes answered ·

Surely it matters after the initial set-up.

What if the unit is removed and sold to someone with a different battery voltage?

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nickdb avatar image nickdb ♦♦ commented ·

I's non-volatile config remains in place unless changed. It won't auto-configure the second time.

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scoraigwind avatar image scoraigwind commented ·
It will be necessary to change the battery voltage settings, if the voltage is different. This can be easily done by reading the manual.
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klim8skeptic avatar image
klim8skeptic answered ·

@scoraigwind Battery BMS's will disconnect if they are unhappy.

Victron SuperPack will disconnect upon " over discharge, over charge or high temperature."

Mppt's seem to be able to handle that ^.


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