question

reggie-grant avatar image
reggie-grant asked

MPPT 150/35 receiving voltage but not outputting any amps? App says it's in bulk mode?

630W of solar (3 210w panels) 24volt

24v Lifepo4 battery sitting at 26.4volts currently max I charge to is 29volts

incoming voltage is at 119.3volts max is just north of 125volts OC


System was working fine for months it's just setup as an emergency back up for my fish tank as well as my deep freezer and main fridge incase of emergency. It's currently been running everything but my main fridge for about 3 months with no issues. At least it was until today decided to take a look at my battery SOC when I noticed I was getting Zero watts from the panels thought it was odd so went to look out the window to find not a cloud in the sky. Took a look at the wires nothing was warm all connections were tight. Checked with multimeter to confirm voltage, everything checked out but no amps coming out of the charge controller. Went outside double checked all connections from the panels everything was in order. On a whim I shut off power from the panels via the disconnect and rechecked voltage nothing at the charge controller as expected still 119v at the line side of the disconnect as expected. re energized the disconnect and saw voltage at the charge controller via the app but still no amps from the charge controller. At this point figured since it wasn't working anyway I decided to shut off the entire system PV voltage first the cut power from the battery. Plugged in my ac charger to top off the battery while I hit the internet to see if anyone else has had this issue. Found a bunch of old posts here and there but not much info on what it could be just a few mentions about updating firmware or checking the BMS. It was over 30 min since I shut it all down I decided to check for a firmware update since I hadn't updated anything since day one of install. Turned on the battery side waited for it to boot up and checked the firmware only update I found was for the bluetooth so updated that. Figured I'd turn on the panels again and wouldn't you know after about 10 seconds I started getting wattage readings from the charge controller. I still don't know what caused it to stop working or restart . And I can't find any relevant information about this issue.

MPPT SmartSolar
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3 Answers
klim8skeptic avatar image
klim8skeptic answered ·

Check the fuse and cabling between the mppt and battery.

Post a screenshot of the mppt history showing Min and Max daily voltage.

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reggie-grant avatar image
reggie-grant answered ·

It's been several months since I've been here but just found something that made me want to update this post with some new information.

Recently had the Charge controller stop charging the battery once again, same issue as before full solar voltage but no amperage. Tried everything as before shut down the PV array disconnected the battery etc etc.


screenshot-20230315-120000.jpg

Then I noticed the -0 F temperature reading. I have no temperature probes on my setup at all so where is that reading coming from? Went into the settings and disabled both the temperature compensation and the low temperature cut-off and wouldn't you know the charge controller started charging my battery once again. I have no idea why this setting was on in the first place but so far it seems to have working again.

screenshot-20230315-124147.jpg

I putting this here since there is no other information that I've found on this topic anywhere and hope it will help someone else out.


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jetlag avatar image
jetlag answered ·

This is a kind of "known" Bug I would say. I had the same issue already twice in approx. 5 month of operation. One time the mppt charge controller showed -273°C, one time it showed -18°C.

The behaviour was exactly the same. No reason why this temperature should drop that much.

After a battery and PV disconnect, the chargers works again.

See here my post to that topic: MPPT 150/70 Showing negative temperature of -273°C

Several other user report the same issue during the last few month. Any, from Offgrid Garage, also mentioned and reported it some time ago in a video.

Hopefully one of the further updates will solve this.


Edit:

What is kind of strange here, that -18°C (what is 0°F) seem to be a kind of threshold.

2 comments
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kevgermany avatar image kevgermany ♦♦ commented ·

I think that some MPPTs have an internal temp sensor.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

What is kind of strange here, that -18°C (what is 0°F) seem to be a kind of threshold.

HMmmm. 273 - 18 = 255. maximum value of 8 bits ??

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