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killergoose avatar image
killergoose asked

MPPT 100/50 producing voltage but no current

MPPT 100/50 with bluetooth dongle connected to LG 415W solar panel and connected to 2 x 200Ah lithium batteries. Seems to charge intermittently. Yesterday it charged nearly 1.8Kwh and battery was 65% charged, voltage 13.16V. This morning there was voltage of 47.45V from panel but no current and no current going to battery. Voltage at battery terminal of charger agrees with voltage at battery terminal. See attachments for Victron Connect screenshots and layout of system. Charged voltage for battery is set at 14.20V, absorption 14.20V and float 13.50V. Any ideas why no current at present? I had three days of no current then yesterday was perfect and today nothing again. History also attached.IMG_3221.pngIMG_3222.pngIMG_3223.pngIMG_3224.pngIMG_3225.jpeg

MPPT Controllers
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img-3222.png (74.7 KiB)
img-3223.png (54.8 KiB)
img-3224.png (100.8 KiB)
img-3225.jpeg (2.4 MiB)
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klim8skeptic avatar image klim8skeptic ♦ commented ·
I use similar circuit breakers on the output of my mppt.

I have had it trip maybe one a year.

The positive cable between the mppt and breaker looks to be a different colour? Cooked??

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killergoose avatar image killergoose klim8skeptic ♦ commented ·
The cables are the same colour, just a bit of shadow on the photo. I haven't had mine trip since installing a year ago.
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1 Answer
seb71 avatar image
seb71 answered ·

That lithium battery has a BMS which can disconnect the battery? Apparently your battery voltage drops to 0.01V daily, so probably it is disconnected. Unless you are disconnecting it manually for some reason.


Also, when you see 0A into battery (during the day and with the battery not full yet), disconnect the PV panels and check if the MPPT remains powered.

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killergoose avatar image killergoose commented ·

Thank you for your swift reply. I have been turning off the system quite regularly to see if it would reset things, so that might explain the 0.01V readings. I will leave it active for a few days and see if it still shows the 0.01V. I turned off the PV and the MPPT is still powered. It is now charging, so possibly turning off the PV changed something? I have Polinovel batteries with built in BMS but I can't access the BMS directly. Can I check it somehow?

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seb71 avatar image seb71 killergoose commented ·

If/when you want to disconnect the MPPT from the battery, make sure you first disconnect the PV array from the MPPT.

When connecting it back, do the same operations in reverse order: first connect the MPPT to the battery and only after that connect the PV array to the MPPT.

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I turned off the PV and the MPPT is still powered.

And just before you disconnected the PV, was the MPPT's battery charging current 0A?

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killergoose avatar image killergoose seb71 commented ·
Yes, the charge current was 0A.
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