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massimo-franco avatar image
massimo-franco asked

My new Bluesolar MPPT 100/15 doesn’t charge my battery

Dear people,

I equipped by boat with a 98W poli flexible panel connected to a Bluesolar MPPT 100/15 monitored by a VE. Direct Smart and directly feeding a Exide Es900 Gel Battery 80A.
First and last charge occurred 21 day ago when Vbat passed from 7,53V to 14,06 in two day with a global amount of charge power equal to 42W.

In the meantime I used regularly some services reducing progressively the battery charge but without any support the MPPT regulator also when Vbat was more than 1V lower from FV as described in the manual for the daily use following the first charge.

Today Vbat was 9,72V, too low for many services, FV was 13,4 but none charge from the regulator. I had to start engines to charge battery!!
It’s normal that?! Is it possible to force the batterylife algorithm to charge anyway?! Money down


Thanks in advance for any help

MPPT Controllers
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5 Answers
Daniel avatar image
Daniel answered ·

Hey, you write that your Battery was at 9,72V and your PV had only 13.4V. Why did i write only? Because you need at least 5V Voltage difference to your Battery for the MPPT to start Charge.


So your PV should at least have 14.72V to start the charge Process. What Cells do you have connected and how much?

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

Check the wiring ans all fuses between the MPPT and the battery.
(one fuse is directly at the MPPT next to the connections)

Please make some screenshots of VictronConnect.
(main screen, history and battery settings)

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massimo-franco avatar image
massimo-franco answered ·

Thanks Daniel,

5V of difference it what happened 23 days ago. Therefore I read in the manual that the following days should be necessary only 1V of difference. Anyway I had mounted on top of my bimini a 98W polycrystalline panel as in the first picture

I’havent space over Bimini for an additional panel;

Thanks Matthias,

I just checked the fuse and it was OK as for as any connections. Led green Is blinking as second picture.

Today there’s partially cloudy whether conditions on central of Italy; external temperature is 28C* and a couple of degrees inside the engines locker which does not work today.

The current battery level has been achieved yesterday with the engines support.

I attached here some screenshoots:

3) the current status

4) the chronology of last days;

5) the chronology of the first charge 23 days ago;

6) and 7) the configuration battery;


Next days is planned a little cruise of some day. Thanks for any support.



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Daniel avatar image Daniel commented ·

When the day starts, and the sun rises, you need at least 5V more on your panel than the battery voltage for the mppt to activate charge mode. When it is in charge mode, the voltage of the cells to the battery only needs to be 1V for charge mode to stay on. If it falls below that 1V difference, it stops charging mode. You need a panel that has a higher output voltage.

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massimo-franco avatar image massimo-franco Daniel commented ·

Thanks Daniel, but may be I need a regulator that doesn't do all these problems. A friend of mine with the same panel and on-board services similar to mine returns every evening to the Barbour she with a fully charged battery using a Chinese regulator that costs only € 30 !

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massimo-franco avatar image massimo-franco massimo-franco commented ·
Not Barbour but harbour
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massimo-franco avatar image
massimo-franco answered ·

fc2d6954-34d8-40f7-be0c-eaea1ec7d1b6.jpeg (2.7 MiB)
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klim8skeptic avatar image klim8skeptic ♦ commented ·

Your panel only has 24 cells? ~ needs 36 cells, Vmp/Voc below mppt input voltage range.

Your panel is 2/3 shaded ~ solar panels need sun.

Your solar panel left the factory damaged ~ corners of cells broken.

One cell has a different orientation ~ by design, or bad manufacture.


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massimo-franco avatar image
massimo-franco answered ·

The other pictures

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3de12fc5-c46b-41e1-9db2-210c760b8840.png (215.3 KiB)
d6cc5ead-0968-4617-a7ae-1681a83618f6.png (230.9 KiB)
784c4cd0-e665-4205-bff9-6bb7fa1e2a8b.png (256.6 KiB)
b58d2d47-bcd1-489a-9cff-e216bad352b9.png (204.7 KiB)
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·
Your PV voltage is to low.

What does the datasheet of the panel say about open circuit voltage?

Discharging a 12V battery to 9V or lower every day will kill the battery quickly.


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massimo-franco avatar image massimo-franco Matthias Lange - DE ♦ commented ·

Thank you Matthias for your attention, but my main requirement is not to preserve the integrity of the battery for posterity but rather to always have the boat services every available for all the duration of my short summer holidays. Sure you will understand that the behavior of this regulator does not help me. Neighbors of the dock with regulators of other brands do not have the same problems as mine and every evening they return to harborage with the battery fully charged.


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Matthias Lange - DE avatar image Matthias Lange - DE ♦ massimo-franco commented ·

As I wrote, check the datasheet of your solar panel.
14V is very low for a normal solar panel.

If this low voltage is normal for your panel you might be better with a PWM charge controller.

If the datasheet say you panel should have a higher voltage (normally "12V" solar panels have around 21-22V Voc) then your panel seems to be defective.

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