Plugging in a MultiPlus-II 120V 12/3000/120-50 via a household outlet

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roblatour asked Jan 7, '24

Plugging in a MultiPlus-II 120V 12/3000/120-50 via a household outlet

I have a MultiPlus-II 120V 12/3000/120-50.

For this, my question is, can the unit's AC IN be wired thru to a plug, which in turn is plugged into a standard household 120 volt power outlet?

I read the datasheet and it says the maximum AC input current is 50A (but doesn't say what the minimum is).

The user manual says the same, but also says "Recommend fuse or circuit breaker 50 A" - which I obviously don't have in behind my household outlet - likely either a 15 or 20 amp breaker (will have to check that tomorrow).

Multiplus-II

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madcodger answered · Jan 07 at 02:50 PM

I have a 24V, 3000 KVA Multiplus that powers a small "shed" on our property (used as an exercise studio). Winters here can mean no sun, often, and I got tired of pulling out the generator to recharge the batteries last winter. So over the summer I trenched in a single AC line (in conduit) from the closest building with AC power. I didn't want to make this a permanent install because we may move these sheds to a different property in the future. So, rather than terminate into the AC panel in the source building, I ran it the conduit to terminate on the outside of the source building, under my tractor shed cover, where there's an existing AC outlet (GFCI) with an outdoor cover. I then terminated the AC line at the source end with a male plug, and connected that to a high amp device controller controlled by our home automation system (used for things like dehumidifiers).

This means that I can just energize the AC line connected to this outlet (through my phone) when I need to recharge the batteries due to periods of little sun, and otherwise it's just a dead line. The key thing is to limit the AC in amperage via the Mutiplus configuration. I set it to 10 amps, which is fine for recharging the batteries - it just takes a few hours, during which we can use the AC loads connected to the Multiplus without issue (usually no more than about 150 - 200 watts anyway). The Multiplus thinks I have it connected to a generator. The AC circuit is rated for 20 amps, so I can even use it (back at the source building) to power a 400 watt tractor engine block heater while I'm recharging the batteries.

I've now wired the generator start relay on the Multiplus to a dry contact sensor that "talks to" the home automation system. So, when the batteries get low enough, the automation system can just turn on the AC circuit automatically, and then turn it off when I get back to a predetermined state of charge. So far, it's all working like a charm. I've even used it during sunny periods, and it worked perfectly - it just charged the batteries faster (still under 20 amps per battery given my paneling and winter sun). Anyway, hope that little anecdote is helpful to you.

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roblatour commented · Jan 07 at 05:38 PM

Thanks - I figured there must be a setting in the Multiplus someplace to limit the current, and limiting it to 10 amps (as you did) will be perfect for me. Also, I like the idea of my home automation system turning on and off the AC circuit automatically. I already have Home Assistant installed, and am using it to control other plugs. Are you controlling a wifi-plug plugged in between your Multiplus and your household power, or are you connecting your Multiplus directly to Home Assistant in some way and then toggling on and off the AC charging power in that way?

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Answer 1 · 2024-01-07T05:10:46Z

JohnC answered · Jan 07 at 05:10 AM

@RobLatour

The minimum Input Current Limit you can set on that unit is 7.5 A (while still retaining Power Assist functionality).

I don't have an issue personally with doing that plug thing, but your local utility may have. Just don't go setting up anything to export power.

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roblatour commented · Jan 07 at 05:32 PM

Thanks very much, that is good to know.

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Answer 2 · 2024-01-08T12:21:51Z

madcodger answered · Jan 08 at 12:21 PM

I use Hubitat (which will work with Home Assistant) as the automation controller and a z-wave appliance switch from Zooz for this, but a wifi switch should work well (just make sure it can handle the amperage as it's a fire risk if not designed for that). The relay at the Multiplus is a Zooz Zen 16 Multirelay device, which is overkill but I had it laying around on my workbench. I also have Hubitat send me a notification when it is turning the relay on or off, so I can double check things, but so far it has worked perfectly. None of this is needed in summer as there's plenty of sun, but winters are a different story. Lately I've been using AC every 2-3 days. Ugghh.

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roblatour commented · Jan 08 at 03:02 PM

Thanks, again very helpful!

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