SmartSolar 100/50 not charging LiFePo4 batteries most of the time

DIY
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I DIYed the setup in my campervan after a ton of reading. I have 4x 100w Renogy panels connected in series to a SmartSolar100/50 MPPT. I have a CerboGX. I also have a pair of Orion 12/12/50’s. These all connect to a LynxShunt and LynxDistributor that hosts a pair of 300aH third-party LiFePo4 batteries in parallel.

The DC/DC chargers and MPPT are connected via smart networking. Everything is plugged in to the CerboGX. DC/DC chargers are manually set in software to charge mode with a lifepo battery setting. The MPPT is set with the physical switch to mode7 for lifepo.

After a week of not going anywhere, I started my van and my whole system sprung to life. It looked like my batteries were dead. So I could isolate the non-victron batteries from the victron everything else, I flipped the battery switch to disconnect my house batteries from the sytsem and then put the AC charger I’ve got on the bank. When the bank was fully charged, I put a capacity tester on the bank and completely drained it. According to the capacity tester, my 600AH bank tested at 606AH.

From basically-drained, I started the van and drove for about an hour. During that time, the pair of DC/DC chargers were happily charging my battery bank. According to VictronConnect, I got roughly 75aH of juice into the bank. I left the van overnight expecting that when the sun came out, I’d get all kinds of solar power into the panels.

At first, I was. I was slightly shaded, but I still got about 100w worth of power flowing into my panels. As the sun rose, the van was in some shade from trees, and power dropped to zero. Now that it’s 100% in the bright afternoon sun, I see that my panels are pumping out 89.8V at 0A and the MPPT state is “float”. I’m draining my batteries with my electrical system instead of charging them with solar. There’s no possible way that this 600AH pack got charged up with an hour of driving and a morning of low-angle sun.

What should I be looking into in order to determine why my solar setup isn’t working like expected? (or like the previous Renogy charge controller I had before my lithium upgrade)

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Hi, One thing i see is that your mppts are connected with smartnetworking and cerbo, thats not possible, use just one connection

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I’ll disable the smart networking soon. While I was out checking something else out, I was playing around with a few more things. The red light on the Lynx Distributor is lit up where the MPPT plugs in. I suppose it’s possible that either the fuse blew or that there’s something up with the Distributor. Currently, there’s 1.5v DC on the wires between the Distributor and the MPPT. I’ll swap out the fuse this weekend and report back with my findings.

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Check the battery voltage the mppt reports, and compare to the actual battery voltage.
Could be a blown fuse/breaker between the mppt and battery.

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I started looking into this. I measured 1.5v at the mppt, but the mppt reported 14v. That’s when I looked down and saw the red light on the Distributor. I assumed a blown fuse, but thought it was weird because I had power from the panels before lunch.

I opened the Distributor. I was about to pull the fuse when I saw…

The guy that was in there before me (that, strangely looks and sounds just like me) didn’t tighten the nut that holds the fuse down. I grabbed a torque wrench and torqued it down. When I powered the system back up, I immediately had power running from the panels, through the mppt, to the battery bank.

I spent weeks looking at the batteries, settings on the mppt and shunt, and it was as basic as tightening down the fastener.

Thanks for your help. I feel like an idiot. Hopefully, someone can learn from my experience.

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