Victron Threshold or Faulty Solar Panel?

[Deviant Tubs]

Evening all!

So just got back from a recent Bank Holiday camping trip. Absolutely superb couple of days at Shambala Festival near Coventry. Our 9th year of going, for my money best festival in the UK! But I digress.

One thing I was curious to see was that the Victron Solar controller (in my case the 100/20 MPPT) wasn't charging even on a bright sunny day!

The battery readout for the Lifos 105AH was running at 13.1volt (which I believe is approx 40% remaining charge?)

Curious about this I checked the Victron app. I noted that it says that one reason for no controller activity is due to the panel needing to be running at 5volts or greater than the Battery to begin the charging process.

Now I appreciate the need for this buffer, but I can't help but think this is a little bit odd?

Firstly, because that would require the Panel to be running at around 18volts or higher to charge my Lifos when at 13V or less. Which is a bit strange given that my 160w semi flexible panel runs at Max power Voltage 20.2V (if memory serves correctly)

Secondly, I've never noticed this 5v threshold requirement before? Does anyone know if it's a recent addition or Firmware update? Because the panel as always seemed to kick in wherever the battery is anything less than 100%, keeping it nicely topped up at 14.4 almost constantly?

If anyone can shed any light on what might be going on here I'd be incredibly grateful.

As the king of all things electrical, @Dellmassive I would be interested to know what you think in particular

Cheers fellas

 

[Dellmassive]

all totally normal,

The 5V above battery voltage is normal, and only applies to the start of the charge cycle.

once the unit is pulling power the 5v doesn't apply so much, and the panel voltage can be dropped - ie cloud cover.

100w panel would normally be in the 18-22v range. - so again normal.

..........


I've got a couple of 100/20`s and they work great.

so see if you can post the victron MPPT settings and trend charts for a bit more info,

ie Vmax, Vpk etc etc . . .


eg:

 

[Deviant Tubs]

Phew! Cheers @Dellmassive for the 'All Clear' on this one.

It's just weird, I sware I've not seen this behaviour before - it must just be a coincidence that I've never checked when it's been 'waiting' for the 5v Threshold.

I've taken a couple of screenshots from the App which may shed some more light on the subject (or maybe not!)

One thing I'm curious about tho is approx 30 days ago the Lifos was charging upto a comfortable 14.2v (approx) but since then it's barely scrapped past 13.45v?? There's been plenty of sunshine (believe it or not) and there's been virtually no drain on the system - no fridge running, lights, nothing charging etc.

Very strange

 

[TallPaul_S]

One thing I'm curious about tho is approx 30 days ago the Lifos was charging upto a comfortable 14.2v (approx) but since then it's barely scrapped past 13.45v?? There's been plenty of sunshine (believe it or not) and there's been virtually no drain on the system - no fridge running, lights, nothing charging etc.

It's not getting above 13.5v as it's only ever in bulk charge phase, and it'll only get to 14.2v once it reaches absorption/float - ie fully charged.

But, you're only getting 100wh max from your solar (20wh a couple of days back) - that's about 8Ah of power, which is pretty much nothing - do you know what state of charge your battery has been at? If the battery was fully charged I'd expect to see the MPPT in float for most of the day.

From the 3rd August you've not been getting to absorption or float on any day (bar 1) it seems, that's not right.

This is my 305w panel , I have my fridge and a couple of devices running 24/7 and I put back in 500wh (40Ah) per day, roughly.

 

[aferris2]

I've got a 160W panel on my van and getting much better yield than that. Obviously it depends on the amount of sun, but I would expect better charging than that.
You might have a solar panel that is, or is beginning to fail. Have a look at the trend displays (rightmost tab on the victron app. Zoom out so you can see solar voltage and power over a couple of days. Useful to also see the battery voltage but you can only select 2 plots at any time.


If its all working correctly, you should have lots of power coming in during the day (assuming its relatively sunny) and nothing at night. If power drops during the day, it could be the solar panel failing as it heats up. Seen this before, and chucking a bucket of cold water on the panel is an easy way of seeing if it's heat related.

 

[TallPaul_S]

I've got a 160W panel on my van and getting much better yield than that. Obviously it depends on the amount of sun, but I would expect better charging than that.
You might have a solar panel that is, or is beginning to fail. Have a look at the trend displays (rightmost tab on the victron app. Zoom out so you can see solar voltage and power over a couple of days. Useful to also see the battery voltage but you can only select 2 plots at any time.
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If its all working correctly, you should have lots of power coming in during the day (assuming its relatively sunny) and nothing at night. If power drops during the day, it could be the solar panel failing as it heats up. Seen this before, and chucking a bucket of cold water on the panel is an easy way of seeing if it's heat related.

Yep I was just about to suggest that this may be (yet) another failing semi flexible panel...

 

[Dellmassive]

Phew! Cheers @Dellmassive for the 'All Clear' on this one.

It's just weird, I sware I've not seen this behaviour before - it must just be a coincidence that I've never checked when it's been 'waiting' for the 5v Threshold.

I've taken a couple of screenshots from the App which may shed some more light on the subject (or maybe not!)

One thing I'm curious about tho is approx 30 days ago the Lifos was charging upto a comfortable 14.2v (approx) but since then it's barely scrapped past 13.45v?? There's been plenty of sunshine (believe it or not) and there's been virtually no drain on the system - no fridge running, lights, nothing charging etc.

Very strange

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Looking more like your panel maybe failing,

And unable to generate the power any more.


You was getting 25v or more Vmax before looking at those charts.

For a few pics of the panel, and the controller.

Have you checked all the connections are good and tight.

 

[Deviant Tubs]

This is the trend across the last 30 and 46 days respectively...

 

[Deviant Tubs]

The panel itself looks pretty decent to my eye, no obvious bleeding or blistering

 

[TallPaul_S]

Have you got a shunt or battery bms app that shows the current state of charge?

It looks like from about mid way on your second chart, the battery stopped being charged to full (no spikes to 14.2v) and then the voltage has just tailed off with no or little solar.

 

[Deviant Tubs]

 

[Deviant Tubs]

Have you got a shunt or battery bms app that shows the current state of charge?

It looks like from about mid way on your second chart, the battery stopped being charged to full (no spikes to 14.2v) and then the voltage has just tailed off with no or little solar.

This is where the plot thickens...
It's a Lifos battery and the sodding Bluetooth app is about as useless as a chocolate teapot! I'm currently in the process of discharging the battery and hopefully resetting the app

 

[TallPaul_S]

View attachment 257036View attachment 257037

What are the extra wires going into the PV inputs on the MPPT? I'm assuming the red and black are from the solar panel.

This is where the plot thickens...
It's a Lifos battery and the sodding Bluetooth app is about as useless as a chocolate teapot! I'm currently in the process of discharging the battery and hopefully resetting the app

No smart shunt I'm assuming? Although we can see from the voltage that it's not being fully charged.

FYI this is mine for the same chart, you can see it's getting to 14.2v each day along with the solar peaks.

 

[Deviant Tubs]

The cabling to the MPPT is as was when everything was installed back in 2022. No alterations made at any point since. In fact the whole system has been untouched in any way that could lead to such a change in behaviour that I can see.

Could it possibly be an issue with the Battery itself?

This is the 2nd Lifos I've had (the original failed after less than a year) this one only went in 14 months ago so shouldn't be struggling to get to 14v already!!

I could test by shutting off the Solar Charger and plug up the EHU we can see if the battery takes charge upto 14v?

 

[TallPaul_S]

Yeah that would be a plan - basically the MPPT/solar either isn't providing enough charge to get the battery to full (as evidenced by the MPPT only being in bulk phase, and the battery voltage not reaching 14.2v) - which would indicate a faulty MPPT or panel, or the battery isn'r accepting a charge and is faulty and won't get to full.

Hook up the EHU (or take it for a long drive so the DC-DC can charge it) and let us know!

 

[aferris2]

Here's a plot for the whole of today. Had a reasonable amount of sunshine so a good bit of charge going into the LB. Got the fridge running on full freezer mode so there's a consistent load on the battery.

What are the extra wires going into the PV inputs on the MPPT? I'm assuming the red and black are from the solar panel.

Red and black on the left side will (should) be to the leisure battery. The white and blue I assume are the connections to the solar panel. Don't understand what the thinner red cable is for though. Where does this go?

 

[Deviant Tubs]

OK so.

After some investigation I've decided to completely discharge the Lifos and start again.

Firstly this (should) get the Bluetooth Battery Management App working again. Which means I'll be able to assess the SOC.

@Dellmassive I've currently got the Lifos down to 6v. None of the 12v circuit seems to be active anymore (LED lights don't work, 12v sockets are dead) In your book does this count as being 'Fully Discharged' or does it need to be be completely Brown Bread? (0volts?)

After leaving the Lifos 24 hours (and hopefully getting the App working) I'm gonna charge it up via 13Amp EHU and see how the Battery behaves. See if it will take upto 14.2 volts again.

What do you chaps think?

 

[t0mb0]

OK so.

After some investigation I've decided to completely discharge the Lifos and start again.

Firstly this (should) get the Bluetooth Battery Management App working again. Which means I'll be able to assess the SOC.

@Dellmassive I've currently got the Lifos down to 6v. None of the 12v circuit seems to be active anymore (LED lights don't work, 12v sockets are dead) In your book does this count as being 'Fully Discharged' or does it need to be be completely Brown Bread? (0volts?)

After leaving the Lifos 24 hours (and hopefully getting the App working) I'm gonna charge it up via 13Amp EHU and see how the Battery behaves. See if it will take upto 14.2 volts again.

What do you chaps think?

Definitely don't discharge it any further! Lithium batteries are more tolerant of being taken down to low states of charge than lead acid but I wouldn't imagine hammering it down to 6v is particularly good for it.

 

[t0mb0]

OK so.

After some investigation I've decided to completely discharge the Lifos and start again.

Firstly this (should) get the Bluetooth Battery Management App working again. Which means I'll be able to assess the SOC.

@Dellmassive I've currently got the Lifos down to 6v. None of the 12v circuit seems to be active anymore (LED lights don't work, 12v sockets are dead) In your book does this count as being 'Fully Discharged' or does it need to be be completely Brown Bread? (0volts?)

After leaving the Lifos 24 hours (and hopefully getting the App working) I'm gonna charge it up via 13Amp EHU and see how the Battery behaves. See if it will take upto 14.2 volts again.

What do you chaps think?

I'd be tempted to charge it initially with EHU to get it up to 50% or whatever so that you can verify that it's accepting charge and the monitoring is working correctly. After that though, I'd probably switch it back to solar as that's the thing you also want to verify. I'd turn all loads off whilst you do this so that it's clear that all charge is flowing into the battery.

There some confusion in this thread around voltages concerning the higher voltage from the charger meaning that the battery is in float, i.e. fully charged. In fact, it's the opposite with a classic three phase charger, when it's in absorption (i.e. still charging) the voltage is likely around 14.2v and when in float (i.e. fully charged and in trickle/maintenance mode) the voltage will likely back off to 13.5v - you can see this in your screenshots earlier in the thread. Therefore, if the maximum for the day from the charger is 13.5v then that's entirely consistent with the battery being fully charged throughout that day. Note that in order to verify that these actually are the correct voltages for your battery then you'd need to check the battery documentation - lithium batteries can be somewhat different in this regard depending on how the internal BMS is setup - it's not just a function of battery chemistry like a traditional lead acid battery.

 

[Deviant Tubs]

After speaking with Lifos on the phone about trying to get the Bluetooth BMS up and running they confirmed that a discharge should reset it. They also confirmed that 6v was equivalent to a full discharge. They did not seem to think it needed 24 hours to rest(?)

So I switched on the Solar Charger and started charging the battery up again.

The Battery very slowly started taking charge at a rate of 12V and 14 Watts which seems ridiculously low (it's full sunshine and glorious today) and then abruptly stopped at 9v!!!

The voltage from the panel is currently at 14v (again, it's full sunshine outside and glorious) and the Wattage is reading as 0.

I plugged in the EHU and the Battery quickly took charge, zooming upto 13.2V suggesting that the Cell at least is decent.

The BMS App sadly however has not come back online so I can't check the SOC (might pursue a Warranty claim from Lifos because that's major rubbish but that's another story!)

Looks like it maybe the Solar panel afterall. I've ordered a suitcase solar panel to test if the Battery will accept charge from a different piece of hardware.