Why does V Sense power MultiPlus-II and other loads?

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kelflanagan asked Jan 30, '22

Why does V Sense power MultiPlus-II and other loads?

Why does the V Sense connection on my MultiPlus-II 2x 120 V inverter charger power my inverter charger and other items connected to my Lynx Distributor?

Setup:

I Just installed my MultiPlus-II 2x 120V. I’ve attached the AC lines (in and out 1), but not connected to shore power. The chassis ground of the MultiPlus is attached to the chassis ground through the negative busbar of the Lynx Distributor. The negative busbar of the Lynx Distributor is also connected to my battery bank via a SmartShunt. The positive busbar of the Lynx Distributor is isolated from the batteries by an uninstalled class T fuse and the battery disconnect switch being in the off position. The positive and negative DC connections of the MultiPlus are connected to the positive and negative busbars of the Lynx Distributor.

Issue:

When I attached a pair of wires directly from the batteries to the V Sense input of the MultiPlus-II the MultiPlus-II, which was inadvertently on, began to operate and energized the Lynx busbars. The busbars remained energized even after the MultiPlus was turned off. This results in battery draw even with the disconnect switch in the off position. Any ideas or insights would be welcome.

Multiplus-II voltage

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sjung commented · Jun 03, 2022 at 08:28 AM

I second that question!

Setup: We have a similar setup where the positive terminal of the battery is connected to an intermediate switch before the BAT+ connection to disconnect the battery. The negative is always connected.

Issue: With the switch in the disconnected position, and no external shore connection, the MultiPlus II still applies the battery voltage to the BAT+ terminal once the V-Sense input is connected to the battery. Even if the MultiPlus II is switched to 'Off'.

Question: Why?

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Answer 1 · 2022-01-31T09:36:04Z

klim8skeptic answered · Jan 31, 2022 at 09:36 AM

Pretty sure that the Multi will have a small power supply for the internal systems.

You power the AC side, and you will see some voltage on the DC side.

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kelflanagan commented · Feb 01, 2022 at 03:17 AM

@klim8skeptic, I don’t have any power connected to the AC side. The only power attached to the MultiPlus-II is the V sense + and - that are attached to the battery.

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