question

tiranna avatar image
tiranna asked

75/15 Smart Solar not charging since firmware update to v1.54

75/15 Smart Solar not charging since firmware update

I logged into my charger and had to apply a couple of firmware updates. Now the bulk light is on but no currents /watts are showing on the app. voltage 38-40 volt from panel before connection to mppt, (2x 80w) but zero watts or amps. I can connect fine with BMV-712 and battery sense. I reset to factory defaults, but still not working. Any suggestions?

MPPT SmartSolar
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5 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Check all switches and fuses between the MPPT and the battery. There is also a fuse directly at the MPPT.

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petro avatar image
petro answered ·

I have the same issue with my 75/15 since Saturday, although I believe it was the 1.56 update that just happened. I would be interested in trying a previous version firmware if anyone has one available.

PV voltage is fine when measured directly, but drops to practically battery voltage when connected and shows 0 amps. Have tested different PV panel, isolation switch etc.

Have also tried resetting to factory defaults to no avail.

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sacjec99 avatar image sacjec99 commented ·
I have exactly the same problem, 
have a 75/15 mppt with 90 watt solar panel and 2 12 volt lead acid batteries I have 19.67 volts at end of wires, but as soon as I connect them to mppt it shows more or less the same volts as the battery volts. Any help would be appreciated ... 


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klim8skeptic avatar image klim8skeptic ♦ sacjec99 commented ·

Does your panel have 36 cells?

What is the panels Voc?

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sacjec99 avatar image sacjec99 klim8skeptic ♦ commented ·

Our panel is 21,2 voc and yes it’s got 36 cells.

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klim8skeptic avatar image klim8skeptic ♦ sacjec99 commented ·

I would be testing the panels Isc with a multimeter.

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sacjec99 avatar image sacjec99 klim8skeptic ♦ commented ·

I’ve tested it with a multimeter and it’s all ok

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klim8skeptic avatar image klim8skeptic ♦ sacjec99 commented ·

You shorted the panel out and got 4 amps?

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sacjec99 avatar image sacjec99 klim8skeptic ♦ commented ·

Sorry don’t understand

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klim8skeptic avatar image klim8skeptic ♦ sacjec99 commented ·

If you dont understand, learn.

Testing a solar panel Voc and Isc.


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klim8skeptic avatar image
klim8skeptic answered ·

PV voltage is fine when measured directly, but drops to practically battery voltage when connected and shows 0 amps.

This will be the result of a high resistance joint. Please check your fuses, connectors and wiring on the PV side of the Mppt.

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petro avatar image petro commented ·

If it is only so simple! I thought I had checked everything but based on your comment I went back and double checked the MC4 connectors which looked fine, no signs of physical damage or melting. Upon removing the conductors I found that one of them had evidence that water had gotten in at some point previously and there was some rust. I have re-terminated but alas it was dark by the time I finished. Fingers crossed it was just this and a happy coincidence with the firmware.

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klim8skeptic avatar image klim8skeptic ♦ petro commented ·

I went back and double checked the MC4 connectors which looked fine, no signs of physical damage or melting. Upon removing the conductors I found that one of them had evidence that water had gotten in at some point previously and there was some rust.

Yes. I had a problem with a pair of mc4 connectors that I had fabricated.

18 months after installation an array dropped off. Initial probing's revealed that my main multimeter had blown fuses (model specific), no chance to easily measure array Isc.

Further probing with another meter revealed near oc of the pv array.

Disconnected the pv array on roof and array Isc measured fine from mc4's.

Reconnected array to mppt wiring. Repeated Isc test and had a fail.

Tuned out 1 one the mc4 connectors I had fabbed had failed. The metal crimp had not been pushed into the plastic housing enough.

Took 18 months to wriggle free enough to fail.

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petro avatar image petro klim8skeptic ♦ commented ·

Thanks for your encouragement to check again, I can happily report that it successfully charged today.

I wonder how many similar problems I read were due to that sort of issue, considering many are "I can only charge if I have two panels in series and nothing in parallel or single"


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0x4 avatar image
0x4 answered ·

I have the same problem, too

the voltage displayed in the app is dropped from 36 to 6v - and not charging anymore.

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0x4 avatar image 0x4 commented ·

Addition: in the evening the voltage increased to normal level (36v) but today I have 6v again.

Any idea what is the issue?

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klim8skeptic avatar image klim8skeptic ♦ 0x4 commented ·

No idea.

Plz post a pic of you mppt history.

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0x4 avatar image 0x4 klim8skeptic ♦ commented ·

solar.png
Here my current history of the last days. Vmax is always in the evening.

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solar.png (170.8 KiB)
klim8skeptic avatar image klim8skeptic ♦ 0x4 commented ·

You seem to have more than 1 charger?

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0x4 avatar image 0x4 klim8skeptic ♦ commented ·

Yes it‘s a campervan - I can charge externally too

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dwyer50 avatar image
dwyer50 answered ·

75/15 Smart Solar not charging since firmware update. Last week I logged into my charger and had to apply a couple of firmware updates.



my gift card site

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klim8skeptic avatar image klim8skeptic ♦ commented ·

My crystal ball needs clues, to direct you to a solution..........

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0x4 avatar image 0x4 klim8skeptic ♦ commented ·

Has someone new informations about this? I see other posts here in the community with the same problem.

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klim8skeptic avatar image klim8skeptic ♦ 0x4 commented ·

Please open a new question. Your problem seems unrelated to any firmware issue.


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