Installing an Inverter Without Creating a Charging Loop

[NorCal Gordo]

Time to finish off the system...
I've got a new converter that'll work with lead acid or lithium batteries, solar panels/controller and an inverter. Now needing to install the inverter. When it comes to mechanics or plumbing, no problem. I can handle most anything on the TM. When it comes to electricity, well, that's kinda my weak point. Looking for some sort of easy schematic or diagram as to how i properly hook everything together. I know that it is easy to get it wrong, especially with the potential to have a total loop where the batteries get charged as the inverter gets used. Looking to avoid that... Any wisdom here is appreciated!

 

[rickst29]

'Search' is your friend on this topic, I've written a lot of information on electrical upgrades within this forum. Let me provide some definitions first, because the "Converter" does only one job - it "converts" from 120-VAC power to DC power at 13.5 to 14.4 volts.

Your first sentence probably refers to a "power center", where several different electrical parts are built into a single box. Here's my list of those parts:

(1) The converter (sometimes called that "main board assembly"). It should at least have some built in intelligence to choose an approriate output voltage according to battery type, battery voltage, and some "internal smarts" to avoid overcharging batteries. The best ones can be programmed from a cellphone, but they might not provide enough power with spending $$$$.

(2) The 120-VAC circuit breaker board and power bus.

(3) The 12-VDC circuit breaker board. That's usually built inside the "power center box", with up to about a dozen breakers -- but those breakers are only ATC (officially 30A amps maximum, due to the small capacity of current through the two "legs" 40A ATC breakers are available and maybe OK for the "Converter-in" and "battery" ports on that board.)

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The converter has nothing to do with the solar controller (for the panels). The solar controller is like anothe specialized "converter", reducing high panel voltage to a voltage the batteries can handle. But most of those use only one output voltage setting. (That setting can be changed, but it's not automatic.) Like the "converter", the "solar controller" is a one-way device - it pushes power TO the batteries and lows, it should never suck power out.

The batteries are a two-way power source, with both output power and taking "input power" to recharge.
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Your Inverter should be sized for the equipment which you will try to run from batteries and solar alone, when you do not have plug-ins. Are you planning on a coffee maker or toasterd or can opener (those are easier), or a microwave oven, (That's HARDER than you might guess), or the air conditioner?

I run the air conditioner from batteries and solar alone, that's a very hard job for the batteries. I have about 900 Amp Hours of Lithium (LFP) providing 13 volts. My Inverter can pull in about 400 amps continuous, about 700 amps peak. That kind of set-up costs a lot of money, far more than a decent generator.


What appliances do you need to run (at the same time) without 120-VAC from the grid or a generator?

 

[rickst29]

Inverters need to be close to the batteries, due to high current draw.