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Disconnect 12 volt inverter when charging ?

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Tired Old Man

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Feb 19, 2021
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I have a very small setup. 100 watt solar. 30 amp charge control. LiFePo battery and a 1500 watt inverter. Should I disconnect the inverter when charging the battery ? It seems to be charging a capacitor in the inverter.
At 100 watt I need all the power going into the battery. Or would it really mater ?
 
yea,disconnect.your system is struggling.that is a lot of inverter for small 12 volt system.how big is battery?
 
If your 1500 watt inverter draws .84 amps at idle, not unrealistic, it will draw about 20 amps a day. A single solar panel may only push 30 amps back into the battery, so by all means shut that thing off when not in use!!

When you add the panels, make sure they are matching panels or do the math to ensure you do not get too much a loss.
 
Or just switch off inverter.

What sort of charge controller? PWM or MPPT? What voltage/current specs on the PV side?
That will influence what panel specs to look for, and how to wire it (series or parallel.)
 
Hedges said:
Or just switch off inverter.

What sort of charge controller? PWM or MPPT? What voltage/current specs on the PV side?
That will influence what panel specs to look for, and how to wire it (series or parallel.)
Click to expand...
some inverters never really switch off.
 
Just turn off the inverter on/off switch, my Victron and Reliable power will draw bascially 0 current when switch is turned off, if the switch is on but no AC load connected it will draw current around 0.5 ~ 0.8A. I turn off my inverter when not inuse, if you disconnect the inverter you will need to pre-charge the capacitors inside the inverter every time you reconnect the inverter to the batteries otherwise you will large surge current when the capacitors are being charged up.
 
Okay. Thanks for the help. The inverter is off. But still connected with the battery and the solar panel, when charging the battery. If you remove the inverter you have a small voltage from the inverter bleeding off. A capacitor ? Is the loss too small to worry about ?
 
Tired Old Man said:
Okay. Thanks for the help. The inverter is off. But still connected with the battery and the solar panel, when charging the battery. If you remove the inverter you have a small voltage from the inverter bleeding off. A capacitor ? Is the loss too small to worry about ?
Click to expand...
Once the capacitors are charged up, you will have very very small leakage current flowing through the capacitors, you can easily verify that with DC Clamp-on Amp meter, you should have one.
 
Bud Martin said:
Once the capacitors are charged up, you will have very very small leakage current flowing through the capacitors, you can easily verify that with DC Clamp-on Amp meter, you should have one.
Click to expand...
So it won't matter that much if I leave the inverter connected ?
 
My inverter is rated for 1 amp idle draw. That is exactly what it does. I have a battery monitor and when I shut it off, I use one less amp an hour.

I don't know abut this inverter "leakage" when its shut off, but my K-Cup does have "leakage" when plugged in, so there's a computer active or something else inside the coffee maker, but the total draw is only .01 or .02 amps, so I do not even worry about that amount of "leakage." The K-cup does draw 55 amps when brewing.
 
chrisski said:
My inverter is rated for 1 amp idle draw. That is exactly what it does. I have a battery monitor and when I shut it off, I use one less amp an hour.

I don't know abut this inverter "leakage" when its shut off, but my K-Cup does have "leakage" when plugged in, so there's a computer active or something else inside the coffee maker, but the total draw is only .01 or .02 amps, so I do not even worry about that amount of "leakage." The K-cup does draw 55 amps when brewing.
Click to expand...
Isn't 1A idling current draw is when the on/off switch is in the ON position? When switch is in the ON the position, the inverter circuit is still running and will draw current and will still putiing out 120VAC WITHOUT any AC load connected to the AC outlet, when switch is OFF the power for running the micro controller and the inverter circuit are cutoff.
 
Bud Martin said:
Isn't 1A idling current draw is when the on/off switch is in the ON position?
Click to expand...
That is correct. The rest is I've never measured the amperage draw from the inverter in the off position, but just like my coffee maker, there probably is some, but so insignificant , should not matter just like the one hundredth of an amp my coffee maker draws..
 
I got the battery charged up and tested it. 2.1k watt hours. Give or take a few with my testing. Hooked back up with the inverter in line. It will be a few days but I'll be back.
 
Credit to DavidPoz from online. He explained about the capacitor better than I could. Start at 6:47 or watch all of it.

Best to leave the invertor connected .
 
I added a 80 watt ( new ) solar panel in parallel with my old 100 watt panel. I only seem to be getting a 1 amp increase. At peak sun shine my best is 4.5 amps for a 180 watt system. I can get 3.5 with amps with just the 80 watt panel.
Any thoughts ? Yes it is a 12 volt system.
 
Tired Old Man said:
I added a 80 watt ( new ) solar panel in parallel with my old 100 watt panel. I only seem to be getting a 1 amp increase. At peak sun shine my best is 4.5 amps for a 180 watt system. I can get 3.5 with amps with just the 80 watt panel.
Any thoughts ? Yes it is a 12 volt system.
Click to expand...

Data sheet, label, or voltages/currents from each panel?
Which charge controller?
What is your battery voltage now?

No shade, I assume.
Are wires long and/or small gauge?
 
Hedges said:
Data sheet, label, or voltages/currents from each panel?
Which charge controller?
What is your battery voltage now?

No shade, I assume.
Are wires long and/or small gauge?
Click to expand...
I don't have any data sheets. The 100 watt panel is about 10 years old and is from Renogy . The 80 watt is a Dokio folding panel. The wires are the standard wires that came with the Renogy panel. The wires are about six foot in length. A no name 30 amp charge controller.

Once the sun is up enough today I'll see what each panel is putting out in amps. With both panels in parallel I would hope to get a least 7 amps. 4.5 amps seems to low .
 
There are probably labels on the panels giving Voc, Vmp, Isc, Imp. Take pictures and post them, or transcribe the numbers.

A non-name charger is probably PWM.
Two panels in parallel ought to just add their Imp together. Both should be "12V" panels, about 17Vmp and 21Voc for use with a 12V battery.
I expect a 100W panel to be 5A Imp and the 80W to be 4A Imp, ought to deliver 9A to the battery.

If battery fully charged, it will take less current regardless of panels connected.
Try putting a 120W or heavier load on the inverter so at least 10A is drawn from the battery, then see how much current through the charge controller.

If you have a DMM, you can disconnect panels and test each for Isc.
 
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