willem-hillier avatar image
willem-hillier asked

Trick for lower input current limit?

First let me describe the system I am working on as it might be a bit unusual.

The system is installed in an Airstream trailer for powering a "trade-show" demo and HVAC system for public demos. Typically the loads draw ~4kW continuous, 8kW peak. The use case is to plug the trailer into either an EV charge point OR a 50A RV service (with an EVSE) overnight, tow the trailer to the site for the day and let it run all day, then tow it back to a grid connection overnight.

Additionally, we wanted the ability to "trickle-charge" off a 15A 120V outlet.

  • 28kWh of 48V batteries (12x Renogy 50Ahr LiFePo4 "smart" batteries)
  • 2x parallel Multi-Plus II 48/5000/70-50 230V
  • 6kW of solar with 2x Victron MPPTs (not yet installed).
  • Lynx distributor and Lynx CAN shunt with a Cerbo (not yet installed).
  • AC output: 100A Victron autotransformer feeding split-phase to the panel
  • AC input: manual transfer switch to select between a J1772 inlet (up to 50A at 240V) or a 2:1 transformer to "trickle charge"

The problem is that sometimes we want to use a 15A 120V outlet with the PowerAssist function. We would like to pull ~13A from the outlet (6.5A@240V, at the input to the Multi-Plus-IIs) and supplement the rest of the ~4kW load with power from the batteries.

The minimum current per Multi-Plus is 5.7A, or, on the other side of that transformer, 23A for both.

How can we make this work? If we disable PowerAssist, we can decrease the current limit further but it will not otherwise do what we want, correct?


Multiplus-IIcurrent limitinput current
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1 Answer
Alexandra avatar image
Alexandra answered ·

@Willem Hillier

It may be simpler to just have a dedicated battery charger to trickle charge off limited shore connections. That way varying loads are not a factor.

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