question

gmaijoe avatar image
gmaijoe asked

Solar Charge + Shunt Settings / Calibration

I'm a bit confused on if I'm setting my settings correctly.


I'm using 4 12V X 200AH LiFePo4 batteries in series for a 48V system.


Here is the manufacturer's website about the battery charges: https://goldenmateenergy.com/blogs/goldenmate-blog/guide-to-lifepo4-voltage-charts-3-2v-12v-24v-48vscreenshot-2024-06-26-at-120154pm.pngscreenshot-2024-06-26-at-120204pm.png


It gives the following values for battery percent and charge bulk/float/equalization V.


img-6674.pngimg-6675.png


Here are my settings. My shunt reset to 100% so I'm trying to get to a full charge to reset to 100% SOC.


Did I set my absorption voltage / float right?


Also is my charged voltage right? I saw online that people say to set it 0.2V - 0.3V below float but I can't understand how that would be right as the manufacturer says 58.4V is 100% for a 48V system.


First time building a solar system so any tips / advice appreciated!

MPPT SmartSolarSmartShunt
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pwfarnell avatar image
pwfarnell answered ·

Your settings are mostly good. I would decrease the charged voltage to 54.8V. This gives a bit of room for measurement errors or voltage drop. I would also increase tail current to 4 or 5%.

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gmaijoe avatar image gmaijoe commented ·
thanks - is the idea that the solar charger will charge the batteries up to the 58.4V absorption level (bulk), and then gradually reduce current and level off at 54V float to maintain the battery voltage?


I'm trying to figure out when I should reset the SOC to 100% because right now it is way off.

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kevgermany avatar image kevgermany ♦♦ gmaijoe commented ·
Ignore SOC for now. You won't get it right until the batteries are fully charged. Your shunt does not control things, just reports.

Setting charged voltage just below float is good for lead as there is still charging taking place at float voltage. For lithium better raising it to near absorption.

Depending on where you are it's possible that you're going to need to increase charge detection period. Clouds cutting charge current are the problem. And it's more sensitive the higher the tail current settings.


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