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patrickbeems avatar image
patrickbeems asked

MPPT 75/15 installed. Battery level from 83% to 100% after that, without solar panels

I installed a MPPT 75/15 to my battery Ecobat AGM Deep-cycle 230Ah, which is also connected to a smartshunt 500A/50mV. I did not disconnect the battery whilst installing. The battery level was 83% before installing. After installing the battery level became suddenly 100%.

Back at the harbour I attached the battery to the Victron charger 12V/30AIP22 Blue Smart, and after 10 minutes the Smartshunt was still on 100%, but charging. I let the battery charge until the battery icon was completely 'filled'.

How can I make sure that the Smartshunt is giving me the correct % of the battery when I get offgrid again? Is there a way to reset or to monitor the correct %?

Best regards,

Patrick

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4 Answers
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theo74 answered ·

Are the AGM battery settings in the MPPT the same as in the shunt?

If the MPPT is set to a higher absorption/float/equalization voltage level than set in the shunt, the shunt will get a higher voltage from the MPPT, and will therefore think the battery is 100% full.

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patrickbeems answered ·

img-4247.pngImage CaptionIt should be the same, see also the pictures. I cannot adjust a battery amperage in the MPPT charger.

My battery is set standard on Victron deep cycle (2).

What do I wrong?

img-4246.png

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theo74 answered ·

The MPPT is probably set to a Victron default for AGM batteries, giving an Absorption voltage of 14,4V, and 13,8V float voltage.

Your smart shunt is set to a battery full ”Geladen spanning” voltage of 13,2V. So that is 0,6V lower than the float voltage of the MPPT, the reason why the smart shunt thinks the battery is full already.

Change the smart shunt ”Battery full” voltage to 13,8V. And also check if your AGM battery really can be discharged up to 20%. Otherwise set the discharge "Ontlading vloer” back to 50%, to prevent a very short life time of the battery.

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patrickbeems answered ·

Hi Theo, my battery is an Ecobat 12V 230Ah AGM Deep-Cycle, EDC12-230. According to the seller it should be able to dicharge up to 20% minimum. I will do as you described above next weekend.

Hopefully it is the solution.

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kevgermany avatar image kevgermany ♦♦ commented ·
Discharging deeply severely reduces the number of charge cycles possible before the battery dies. Normal max is 50%, but this is a compromise between battery service life and replacement cost.

Note that setting the discharge floor only affects alarms/warnings/reporting, it does not prevent further discharge, that's for you to control.

If you're charging from solar, set charged voltage just below absorption, increase detection time and reduce tail current in the shunt settings.


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