question

nicola-marrati avatar image
nicola-marrati asked

MPPT 75/15 SMARTSOLAR DOESN'T SWITCH TO FLAT WHEN THE BATTERY IS FULLY CHARGED

Hallo to everyone.

I have a 100w solar panel and two 320A batteries connected with MPPT 75/15 smart solar charger.

The question is : why the charger dosen't switch to float program when the batteries are fully charged ?(I suppose 13,8V the charger could be to float charging as show in the pictures)

I alwais see bulk charging during the day, none absorbition and float switch

Nothing happens also if I turn off the load.

Where is the problem ?

Thank you for every suggestions


I post the MPPT settings and the initial app screen


whatsapp-image-2021-05-29-at-154700.jpegwhatsapp-image-2021-05-29-at-154441.jpeg

MPPT SmartSolar
whatsapp-image-2021-05-29-at-154441.jpeg (55.2 KiB)
whatsapp-image-2021-05-29-at-154441.jpeg (55.2 KiB)
whatsapp-image-2021-05-29-at-154700.jpeg (78.8 KiB)
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2 Answers
pwfarnell avatar image
pwfarnell answered ·

How discharged are the batteries, how many Ah needs to be replaced. 100W of solar panels is quite small if you are discharging the batteries a lot and will really take a long time to recharge. If you have discharged your batteries by 25% then you need to recharge 160Ah, which will take 43 hours at 3.7A. 100W of panels is really a trickle charge for 640Ah of batteries, it might never be able to get to 14.7V.

As a comparison, on my boat in the UK I have 690Ah of 12V AGM batteries and 680W of panels. I could manage with less solar in the summer, but 100W would be too small.

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Can you also make a screenshot of the history?

The MPPT only switches from bulk to float after the absorption voltage is reached, in your case 14,7V.

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