Multiplus-II 12/3000/120-50 120V Input current limit

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kevinc-63559 asked Mar 9, '24

Multiplus-II 12/3000/120-50 120V Input current limit

New owner of the title unit. Would like to set the input current limit rather low, like to 3 amps, in order to utilize battery power for the few hours a day where I draw more than 3 amps from the grid.

I looked for the lower limit in the often quoted spreadsheet, but this unit is not listed. My Cerbo seems to think the lower limit is 9.5 amps, since anything I set below that defaults to 9.5.

I don't have any Cerbo notifications regarding the unit, so presume its at current firmware levels?

(did get one on my MK3-USB which is quickly upgraded).

Per Cerbo screens, this is Product ID 2705 at firmware level 508.

charge current limit multipluss ii

2 |3000

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JohnC answered · Mar 10 at 03:58 AM

@KevinC_63559

Indeed your 2705 has somehow missed inclusion in that list. But there are similar sized models that show 7.5A and 9.5A. I think you can confidently assume yours is 9.5A from your attempts.

I note from a previous post you describe your system as a 'UPS'. Not sure what you're trying to achieve here, but if you can define it there may be other ways to approach it, like the Ignore AC functions.

3

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kevinc-63559 commented · Mar 10 at 04:30 AM

This is a super simple setup of the Multiplus connected to a pair of 12V LiFePO4 batteries in parallel. Grid AC comes in from a wall socket (thus the grid limit), AC goes out via the Multiplus. typically from the Grid, or from the batteries in case of a Grid outage. e.g. Its a UPS with a heck of a lot longer run time than my previous APC could provide, and with batteries that don't get damaged by being drained.

Its also my "first look" at the current technology. Phase 1 if you will. Phase 2 will be wiring in a pair of MultiPluses to provide 240V split phase to my entire office, with a 48V battery bank. Phase 3 will be adding solar to the Phase 2 solution. I've learned a lot along the journey so far.

In any case, now that I have the system, I'm playing around. Although I typically only pull about 3 amps off the system, for a few hours a day I pull around 4.5 amps. Be nice to supplement that extra 1.5 amp draw via the batteries, then replenish afterwards. e.g. If I could set the AC limit to, say, 3.2 amps, the system would work as desired.

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JohnC ♦ kevinc-63559 commented · Mar 10 at 06:51 AM

@KevinC_63559

I read your 'journey' and it's great to see you're excited about your new kit. Not sure how you'll manage the stepup to 48V though.

You can't use the 3A grid limit, but you could exercise your batteries with a zero limit. This is a little tougher without an SOC reading, which might come from a shunt or a managed battery, but you could have a go. Good you're a tinkerer, so the learning curve is just another step in the journey..

This link to show some possible options you might have. Both in choice of direction and additional kit.. https://www.youtube.com/watch?v=4ZsGHi8nKGc

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kevinc-63559 JohnC ♦ commented · Mar 10 at 04:55 PM

Thanks. Sorry if I wasn't clear - the 48V system will be entirely new.

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Answer 1 · 2024-03-09T05:46:41Z

Paul B answered · Mar 09 at 05:46 AM

on the cerbo - under setting select your multiplus II unit and then you should be able to see the input current limit, change this to 3 amps and this will mean that it will never take more than 3 amps from the mains.

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kevinc-63559 commented · Mar 09 at 05:06 PM

I know what the basic function is... I'm telling you it will not accept 3 as input, reverting to 9.5 when I hit enter.

I tried Victron COnfigure as well, and although it will accept it, Cerbo still reports it at 9.5.

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derrick thomas kevinc-63559 commented · Mar 11 at 02:36 PM

9.5 amps is the low limit on that unit with power assist enabled. It will not go lower.

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