question

vanman avatar image
vanman asked

Can I Plug a MultiPlus Inverter/Charger Into a Phoenix Inverter?

I have a Mulit 12/2000/50 with Smart Solar MPPT 100/30 (335W Panel) and a Pheonix 800 connected to my Van's Aux Battery/Alternator and AC into Multi. The System also uses a Venus GX and Smart Shunt with 2 100Ah Lithium (Relion).


I have the Multi's Max Current set to 4.6A, but charger never approaches pulling that load. I have tried with Power Assist OFF and have also tried with it set to 2. Have also tried Weak AC ON and OFF. The Pheonix is never loaded more than 10%-15% of capacity. I have set Max Current to 6, approaching Phoenix 800 rating and still same trickle of load.


Any ideas?

Multiplus-II
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Justin Cook avatar image
Justin Cook answered ·

@VanMan, with all due respect: one inverter shall not plug into another inverter. That's not how any of this works, and you will invariably run into issues no matter what your settings are.

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Justin Cook avatar image
Justin Cook answered ·

@vanman, am I reading this correctly that you have a Phoenix 800VA inverter connected to your Aux battery with its output connected to the AC input of a Multi?

If so, please immediately decommission this system; this is not an acceptable system design, and it will not perform -in any way, shape, or form- to spec.

If not, as it's possible I have misinterpreted your stated equipment and layout, please post a system schematic and/or photographs to document the system as you have it installed and we'll assist you with troubleshooting from there!

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vanman avatar image
vanman answered ·

@Justin Cook - Bay Marine Supply USA, thanks for reply. I have patterned my system after a couple others Van builds who have been using small front mounted inverters to feed via AC (to keep wire size small) to rear Inverter/Charger near batteries and solar feed. I have not seen where Victron says this is a bad idea. Can you explain what makes this a bad idea. Thanks much.

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Justin Cook avatar image Justin Cook ♦♦ commented ·

@vanman, Victron says to install their devices according to their user manuals, and installing the devices in any way other than expressly stated in the manual is a bad idea - there are so many bad installation practices out there that it would be impossible to list them all, and is instead much easier to say "here's how to install this, please install it that way".

I don't know of these other van builds, but they should stop too. The proper way to charge your house batteries from your chassis/start battery is with a DC-DC Charger like the Orion-Tr Smart or, worst-case, a VSR like the Cyrix series or even a Buck-Boost for that matter.

The number of ways in which using a small inverter to power a large inverter/charger just to charge your house bank is an ill-advised idea are, unfortunately, far too numerous to even list.

Bottom line: This practice is not supported, and your system will not perform to spec because it is not connected per specifications.

It is impossible to troubleshoot a system that isn't connected appropriately.

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vanman avatar image vanman Justin Cook ♦♦ commented ·

It does seem Victron anticipates low power sources for their Multi's by having the option to set max input current which is exactly the parameter I would like to set and work as described in their manual. I do not understand why a high quality sine wave inverter like their phoenix is not an appropriate charger source when the man current is set to 4.5 (spec).


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vanman avatar image
vanman answered ·

When I look at the Minimum Shore Current Limits 07-2019 xls file, it states: There will be no minimal limit when PowerAssist function is disabled. I do not anticipate needing PowerAssist's magic, so if I turn off PowerAssist, can I set the minimum charge current limit to 5A or does it mean I am unable to set a minimum limit when PowerAssist is off?


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