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wmb asked

why does solar not fully supply load and draw 50% from battery?

Victron 100/70, 1000W renology panels, 3000W AIMS inverter, 620 Ah lithium batteries on truck camper. When battery full (or nearly full) and in float mode and AC is on, the 55 amps needed to run AC is not provided by solar - instead its about a 50% battery/ 50% solar split. I want to run AC on solar during daytime and conserve battery for nightime use.

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jacobjned avatar image jacobjned commented ·

A quick one, kindly confirm, that you mean Victron MPPT 150/70? Can you please share a screenshot of the settings you have used.
If I work on, 55A x 12V = 660W, does your MPPT via the VictronConnect app show that '300Wish' as PV generation?

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wmb avatar image wmb jacobjned commented ·

Yes mppt 150/70 (sorry). Pic of settings below. I use a trimetric monitor to track amps in and out. Thats how I learned that mppt was not supplying full load from PV. To expand, when load is increased from 55amps (AC draw) to 100amps (microwave) PV system will bump up wattage to the amount that provides about 50% of the load, with the rest coming from battery. So I know when AC runs with draw of 55 amps and the battery is providing 25amps and PV 30 amps, that more PV amps are available. Switching to the microwave 50amps comes from PV while 50 come from battery. IMG_6822.PNG

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img-6822.png (241.5 KiB)
jacobjned avatar image jacobjned wmb commented ·

The settings you have used are usually for Victron Lithium Batteries (if I am not wrong). Are you using Victron Lithium Batteries? Other brands/manufacturers of Lithium batteries will have their own unique absorption voltage, float voltage setting, max. absorption time, etc. For the '12V' Victron Lithium Battery float voltage is about 13.5V. If you are not using Victron Lithium battery, and using another brand of battery, it MAY be able to take higher float voltage, i.e. higher than 13.5V. Therefore when the MPPT reaches float voltage, the PV is limited to push NOT more than 13.5V to your battery. This could be a possibility of why you see the limitation. Like @kevgermany said, you need to make sure you are following the battery manufacturer's spec for programming the MPPT.

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kevgermany avatar image kevgermany ♦♦ commented ·
Once the MPPT goes into float, it will stay there until battery voltage drops. With lithium, this can take a while due to the flat discharge curve.

There's a rebulk offset setting in the MPPT. Battery voltage needs to drop below float by this amount before the MPPT comes out of float. Try reducing this. You may need to tweak it a few times. You may wish to increase float voltage as well, but stay within battery maker's recommendation

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