MPPT 100/30 No charge

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Anthony Brickner asked Jul 12, '21

MPPT 100/30 No charge

Hey there, I'm new here and could really use some help. I've been working on a solar build for my van and continue having issues with it. I don't know much about solar setup and have done this entirely on my own. I followed faroutride's electrical diagram nearly to a T for the installation. The main differences are in the wiring I chose to use as I couldn't afford the marine-grade stuff that they used.

Specs:

3x100W Renogy panels wired in series (about 5 years old) (8AWG solar wires to 40A fuse)

Victron 100/30 MPPT Charge Controller (8AWG from PV, 10AWG to 40A fuse to busbar for batteries)

2x 125Ah Vmax Tanks AGM Deep Cycle 12v Batteries (2AWG wired in parallel)

Positive switch between battery and loads (2AWG)

Victron BMV 712 monitor and negative shunt (2AWG)

BlueSeas Positive and Negative Bus bars (Ground to the chassis of my van)

Victron Orion DC to DC charger connected to the starter battery for the van (6AWG)

Victron Bluetooth Temp + Voltage dongle (recently added as an attempt to fix my issue)

Samlex 30A shorepower 12v charger (10AWG)

My issue is that the MPPT 100/30 hasn't been charging my batteries. I sent it back to where I ordered it from and they were able to get it working fine. So I know the problem is within my setup. According to the VMAX tank website, these batteries should float around 13.5-13.8v. When I received the batteries, they were charged at 13.75. But it looks like their SOC should land around 13.08 in my current climate. I reached out to Vmax about these discrepancies and got no response. So I don't know what the actually charged voltage should be for these bad boys. According to the Victron app, the MPPT and BMV are both showing the current voltage for the batteries, give or take a volt. The dongle is showing 77 degrees Fahrenheit and the same voltage. I tested with a voltmeter on the batteries and loads, everything is reading the correct voltage. Same on the MPPT terminals themselves.

My MPPT has been stuck in blinking Bulk since I reinstalled my setup after moving it. Meanwhile, my batteries are just operating a 12v dometic fridge and are slowly dying. Right now at about 12.7v. I've been charging them with a Samlex 30A shorepower charger in the meantime. But I want this expensive solar setup to work. Please help!

MPPT Controllers MPPT SmartSolar

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wkirby answered · Jul 12, 2021 at 09:01 PM

The 4V drop over your fuse is where the problem is. Did you check the fuse and its connections. The MPPT is reading 16.6V on its terminals as it tries to make current flow, but it can't due to there being an open fuse or bad connection between it and the battery. Once this connection is restored then it can start charging again.

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Anthony Brickner commented · Jul 21, 2021 at 01:29 PM

This was it! It might seem silly but the diagram I was using called for a 10AWG wire when I needed 8AWG coming off of the fuse and to the battery terminals on the MPPT. I switched those out and everything worked great from then on. Thanks for the comment! This inspired me to try it.

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Anthony Brickner answered · Jul 21, 2021 at 01:25 PM

Okay so I figured it out! The diagram I was using called for a lower wire gauge of 10AWG coming off of a fuse that lead to the battery inputs for the MPPT. Apparently that was enough to make the full system pretty unhappy. I swapped out the wires to match the solar wiring (8AWG) and everything works perfectly now.

Thank you everyone for the advice and help!

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Modifications Space

Node Red Space

Answer 1 · 2021-07-12T19:48:47Z

Mike Dorsett answered · Jul 12, 2021 at 07:48 PM

Have you tried using the BMV to check the voltage set points for the MPPT? (or set the rotary switch on the MPPT to the correct position for the battery type?

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Anthony Brickner commented · Jul 12, 2021 at 08:06 PM

Right now I have the set points to AGM spiral cell. And then I have the BMV set to 13.5v for charged. I'm not even sure if that's the correct charged voltage but I'm assuming since the Vmax batteries came charged at 13.75, 13.5 is probably a safe bet. I believe the AGM preset on the MPPT is 13.7 for Float and 14.7 for Absorption. However, it doesn't seem to want to go over 13.15 most days. So I know it isn't staying on float. It doesn't seem like the MPPT is actually talking to the batteries.

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Answer 2 · 2021-07-12T20:47:02Z

Anthony Brickner answered · Jul 12, 2021 at 08:47 PM

So I checked the voltmeter on all of the connections right now. And on my 40A fuse between the battery terminals on the MPPT and the load bus bar, I have a 4v drop. It says the battery terminals on the MPPT are reading 16.6v. Then when I get to the busbar it's 12.7v. Obviously, I don't want a 16.6v busbar on my 12v system. But something seems amiss there to me. Everything else measured 12.7v and my PV is at about 54v.

I'm going ahead and attaching the settings screenshots in here as well for good measure.

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screenshot-20210712-163725.png (193.0 KiB)

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Answer 3 · 2021-07-13T01:09:32Z

ddickov answered · Jul 13, 2021 at 01:09 AM

Hi there I would recommend selecting custom profile and inputting the exact values from the battery manufacturers specification sheet, can I ask is the mppt connected to the load side of the shunt to see the charged KWh value it would need to be on the load side of the shunt and not the battery directly, in the manual tells you how to reset to factory settings maybe worth a try also thanks david

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Anthony Brickner commented · Jul 21, 2021 at 01:27 PM

Hi David, thanks for the feedback! It is connected to the load side of the shunt. I was able to figure it out and I posted my findings above. I really appreciate your response, though, and I'll keep it in mind for future issues. Hopefully, there aren't any. Have a great day!

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ddickov Anthony Brickner commented · Jul 21, 2021 at 08:58 PM

No problem at all anytime, did you get the mppt working ok, another thing I would say is that the battery has to be connected first then solar and if disconnecting it you have to disconnect solar first then battery power.

Hope you got it sorted thanks david

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