question

robert-barnesi avatar image
robert-barnesi asked

MPPT Output Under Load

I've noticed that many times when it's nice and sunny and the batteries are fully charged if I turn on a heavy load the 100/30 MPPT won't provide any current from the solar panel until the batteries are significantly discharged, sometimes not even then. Sometimes it will only start providing current the next day. Why doesn't the MPPT always respond to load on the system by outputing current form the solar panel?

MPPT Controllersdc system
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2 Answers
mattrb911 avatar image
mattrb911 answered ·

Have you looked at the re-bulk voltage setting? The charger should switch back to the bulk stage when it reaches that level

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robert-barnesi avatar image robert-barnesi commented ·
Only thing I could find in the manual was:


The default setting for restarting the charge cycle is Vbatt<(Vfloat-0,4V) for lead-acid.

Vfloat is 13.8v and the system voltage was probably down to around 12 volts but still didn't get any current from the panel, just stayed on float...


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mihaitaiosub avatar image
mihaitaiosub answered ·

I am facing the same situation. The chargers are set to 55.5 absorption and 54 float. After the batteries go into float, and I connect a more powerful consumer, or only as much as the house consumes, the chargers do not draw power from the panels except when the battery voltage drops below 54V, the float value.

And what the colleague suggests in the answer above, to use the rebulk voltage at a value as low as possible, I don't think it's right. For a LiFePo4 battery bank, as I have, it would mean starting a new charging cycle when the batteries are already charged. This will destroy them in the shortest time.

Also, does anyone know what the "Load output" setting in the charger means? I use it on "BatteryLife", but I'm not sure I know what it means.

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