January 10, 20242 yr But what do I know? I can see how when I turn on a light or a kettle there is a load and the load causes current to be drawn. But yesterday, an overcast day, I was charging my batteries from the grid and I started wondering how this happens. How does the inverter create a "load" that draws current that can be routed to the batteries? OK... there is a lot of potential across the live and neutral of the feed to my house, but something has got to demand that current flow. So how does the inverter create such a demand?
January 10, 20242 yr 2 hours ago, Bobster. said: But what do I know? I can see how when I turn on a light or a kettle there is a load and the load causes current to be drawn. But yesterday, an overcast day, I was charging my batteries from the grid and I started wondering how this happens. How does the inverter create a "load" that draws current that can be routed to the batteries? OK... there is a lot of potential across the live and neutral of the feed to my house, but something has got to demand that current flow. So how does the inverter create such a demand? High-leveI 2c. I think you need to see the battery itself as the load, and the energy drawn from grid is used to reverse a chemical reaction in the battery from a lower energy state to a higher energy state. Basically pushing electrons against the electrical field's natural flow from one plate to another through the electrolyte. Or something like that. What do I know. And then it's the AC/DC conversion in the charger that's working, applying the appropriate higher charging Voltage above 48V to the battery to get the current flowing in the reverse direction.
January 11, 20242 yr 22 hours ago, Bobster. said: But yesterday, an overcast day, I was charging my batteries from the grid and I started wondering how this happens. How does the inverter create a "load" that draws current that can be routed to the batteries? I like the water analogy... the inverter will increase the voltage across the DC bus, raising it higher than the battery voltage which causes the electrons to flow 'downhill' to the battery. Voltage can be seen as pressure and higher voltage means higher pressure (uphill) and electrons will always flow from higher pressure to lower pressure, just like water. Inversely, when there is a load on the inverter the voltage of the DC bus will drop lower than the battery, figuratively placing it downhill so the electrons will flow from the battery to the inverter. Current can then be seen as the rate of flow of the water (electrons), the higher the pressure difference the higher the flow rate (current). This obviously gets a bit more complicated when doing blending with grid, battery and PV, but the principle is the same, it is all managed by voltage differences.... at least that's my layman's understanding of how inverters work.
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