4x 200W panels on a sunny day will give more than enough power to charge that battery.
800Wx 5 hours = 4kW/h, 280Ah x 12V = approximately 4kW/h.
Iâm almost certain of that ⊠They are flex panels and then a defective panel would short-circuit the other two or not let any current through ⊠the same result ⊠so 0 V at the Mppt
And what is the bypass diodes for?
The diodes should normally compensate for partial failures or shading.
But it could also be a faulty busbar or connector ⊠There have also been faulty MC4 connectors âŠ
So first measure your panels and then you can continue your search ⊠with or without a helmet
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Okay. Sounds logical. Will start the investigating by measuring the panels voltage. And then?
Maybe a misplaced decimal point? 800W of panels is fine for a 280Ah 12V battery.
On the top of the battery âRated energy 3584Whâ. 800W x 5 hours = 4000Wh.
Of course itâs not as simple as that as you wonât get 800W for 5 hours, but itâs fairly well matched if youâre in a sunny place.
Nah. Mission impossible. Denmark. Can be without any sun even for 1 week.
Ah, OK.
In summer you will have more than enough power. In winter not so much.
Iâm in the UK with 6x 175W panels. I donât think the roof of your RV is going to be big enough.
Hey just a quick reminder.
I saw you use a 100/30 smart chargerâŠ
Keep in mind that if you put panels in series your Voltage increases with each Panel you add in series.
Once you go over that 100Volt youâll fry the 100/30 MPPTs capacityâŠ
Just something to keep in mind.
The panels should state the open Voltage on the backside sticker. Something like âVocâ and a number.
Just make sure you donât go near that maximum Voltage 
So, reading back and saw your post with the panels details.
If that is the type of panels you have than it said 23.9 Open Voltage. With those 3 panels in series thatâs about 72Volt on the MPPT Solar input side. Well within the safe margin.
The stated Max voltage is 100 volt, and adding a 4th panel in series would bring the combined voltage to 96ish what is dangerously close to its max Voltage.
In Colder weather the Voltage can creep up slightly, and going over that 100 Volt kills your MPPTâŠ
You can circumvent this by 2Series 2 paralel, what you probably had in mind already, but I still wanted to bring it to attention since it would be a wast to accidentally fry your solar charger
The Voltage needs to raise to 18.25V to start the MPPT. After that, it can keep running down to 0.5 or 1V difference.
Your Voltage drop after charging may just be normal. As long as the mppt has a tiny bit of power, it will be able to keep the float-voltage.
Once the mppt shuts down, you will start to see the actual voltage of the battery.
It is completly normal that the âhigh voltage deltaâ vanishes quickly, it doesnât contain a lot of energy.
For example, once I disconnect the (floating) charger of my sons EV, voltage readings go down to 13.4 in about 40 seconds and finally settle at about 13.3 after some minutes. (Donât expect that 10 Bucks equalizer to have highly precice readings)
Or to say it in even simpler terms, after the charging stops, the batteries âsettleâ at a lower voltage. They need some time to come down to their actual level.
Same principle goes for a battery under load when the Voltage drops below the Voltage at ârestâ but will recover to a higher Voltage a little while after the load is taken of that battery
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Exactly. That is why the 4th one wonât be in series. It will be 2x2 in series then connect together in parallel. In that case I will have 47.8V/21.48A
But thanks for the warning.
But for now I have this 3x200W in series.
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Ah okay. This explains a lot.
Is there any connection between the batteryâs recommended charge rate current (56A or 0.2C) and the MPPTâs max 30A or itâs a very blond question?
They donât need to be the same, if thatâs the question. The maximum 30A are only ever reached in optimal conditions, so would be less most the time and ofc depending on if the panels can produce enough power.
As long as you donât exceed the batteries maximum charge current, the difference will just determine how long it takes to fully charge the battery.
I think your apparent draining problem is because the shunt is wired backwards. Perhaps you could re-wire it and post screen shots of the shunt and the MPPT controller now that you have all three panels in series.
So. SmatShunt is in the correct position now, I didnât touch anything else yet. Suddenly the -Amps went to +Amps. That is good.
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Those screen shots look fine assuming you donât have much sun at the moment. It will be interesting to see those same screen shots later today when it gets dark.