Will improving load power factor reduce battery current?

DIY
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1

I am proposing to install a Multiplus II 48/5000va GX in my home.
Some of my loads have poor power factor eg freezer PF=0.5
If I add capacitors to the compressor will this reduce the current drawn from the battery when running off grid.
Thanks
Bob

2

The starting torque is always the decisive factor for refrigerators and freezers. After that, everything is no problem. I wouldn’t worry about this with a 5000 Multi. The power is completely sufficient.
Nothing can be improved here. Capacitors or extension cables as resistors won’t help here.
So no worries with a 5000 :slight_smile:

3

I think you missunderstood the question.

BoB is refering to a bad Powerfactor of some consumers. If you imagine a consumer, requiring 230W in a 230V system, a PowerFactor of 1 would result in 1A on the AC Side.

If said consumer has a powerfactor of 0.5, the MP would need to provide 2A to deliver 230W of power.

In Grid-Situations, private people are not charged for reactive power - however in Off-Grid situations, the power has to come from “somewhere”.

So, the question is, if a bad powerfactor would result in a higher DC-Discharge, and if improving the power factor would therefore help to increase overall battery duration.

I understand this question, because I thought about this as well, but answering it is beyond my knowledge in that area.

4

@dognose Spot On.
As you say the VA has got to come from somewhere but I can’t quite get my head round whether the battery current depends on PF of the load.
If I had the hardware here I could connect it up and make measurements but I’ve not pressed the trigger on the order yet.
Bob

5

Reactive currents are cyclic, and theoretically wont normally add to the DC current the inverter consumes. Except that the poor pf causes an increase in resistive losses - in the AC cables, compensation capacitors and inductive windings. These losses DO add to the dc current - however in a domestic situation, they are normally quite small. One off grid site I worked on had a particularly bad power factor - about 0.68, and adding a power factor correction unit did lead to an increase in generator efficiency. The thing to do is measure the dc current while switching the correction capacitor into and out of circuit.