Battery conundrum

[suavecarve]

Fogstar 280 ah under the seat. 2 months old no issues.
Attached 350 watts of solar a week ago.
Battery has capacity of 304 ah even though it's 280.
Battery was in 120 ish a week ago and has been very very slowly filling up with solar and was at 141 today.

Overnight (I think) my 141 ah dumped to 5 ah.
I was at work. Wife says she hasn't played with anything. It hasn't moved. There is no 240 connection.

Here are Fogstar and victron screenshots.

Explanations and wild guesses welcome

 

[suavecarve]

There is nothing on in the motorhome apart from the panel

 

[Lenny HB]

Probably the battery BMS throwing a wabbly. Best to fit a shunt fit accuracy.

 

[suavecarve]

So just something that happens and no great shakes ? (apart from loss of battery capacity)

 

[Lenny HB]

It depends if the BMS decides the battery is flat it will shut the battery down.

Any comments RogerIvy

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[suavecarve]

Just noticed on the Fogstar app. The first screenshot is when it was full (ish) at 1505 hrs yesterday.

This screenshot is the next bar (first empty one) at 1845 hrs (it's getting an electric 240 charge atm) tonight
So I m missing 28 hours !

 

[Cush]

That voltage 12.7 is very low for a lithium. 15 ish %. I would get it on charge. The bms won’t detect a small draw that can empty a battery and give a false reading. 12.7 good for a lead acid.

 

[suavecarve]

That voltage 12.7 is very low for a lithium. 15 ish %. I would get it on charge. The bms won’t detect a small draw that can empty a battery and give a false reading. 12.7 good for a lead acid.

Theres nothing in there atm so stuck the 240 on at 18 amps an hour. I ll take it out before bed so will have about 60 in there in the morning as I want to see what the solar will give me on a semi reasonable day in November tomorrow. If I left it on overnight it would be nearly full and gong into absorption and float and I wouldnt see my new solars working tomorrow !

Closer inspection suggests a draw coming out overnight but the Fogstar had been suggesting the amps were going up slowly daily so amp increasing daily and voltage descending daily !

 

[suavecarve]

Another thought crosses my mind.

At about 1500 hrs yesterday (when it possibly turned itself off) is about the time I was checking to see how much solar I yielded from the app.

Is there a button I could have inadvertently pressed "Dump the electric and turn it off for 28 hours" sort of button ?

 

[StillGoing]

I don’t trust the Fogstar app to give an accurate reading of how full the battery is. I very rarely look at it. As Lenny HB says, fit a shunt if you want an accurate measure of how full your battery is.

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[pappajohn]

Remaining capacity 141.1%

How does that work....anything has a total of 100% and no such thing as 141.1%

 

[jezport]

How many cycles has the battery done? You need a few for the BMS to calibrate

 

[jezport]

Remaining capacity 141.1%

How does that work....anything has a total of 100% and no such thing as 141.1%

Has the % sign but means AH

 

[Cush]

Closer inspection suggests a draw coming out overnight but the Fogstar had been suggesting the amps were going up slowly daily so amp increasing daily and voltage descending daily !

The Fogstar app will only show amps in terms of amps /hr charging or discharging current as reflected by the solar input in the Victron app. I think it has just run itself down. I’m guess you charge to 14.2 or 14.4 v at full. That’s why you will get more in than the advertised number of amps capacity. I think the battery just ran itself too low. I’d trust the shunt and not the Fogstar app. As others say above. It needs a few cycle for the % figure to be dependable.

Your Victron app (solar? Shunt? Don’t have one so not too sure) shows a steady drain, counteracted periodically by solar. What voltage do you consider as being a full battery? When you added the solar, did you connect the controller to the battery first and then connect the panels?

 

[Ian_H]

At 12.7V the battery state of charge (SOC) is less than 20%, regardless of what the fogstar app says. Charge it up fully via EHU (until the voltage has got up to 14.2V, ignore the app for now). As has been said already, after a few cycles the bms will sort itself out and the app will read correctly. If you don't have a shunt (I dont) you just need to charge it fully every so often so that you see the SOC get to 100% (not 99%) when the app will recalibrate itself. There clearly is a drain of some sort present once you have the battery charged you can start looking for it.

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[AdrianChen]

Yes looks like the BMS turned itself off on the 8th at 12.45ish, and hasn't come back on - Solar may not be giving sufficient output to switch it back on given the cloud cover etc, but I'm not sure how the fogstar bms works. If you are happy with the connections/fuses/breaker switches you have on the solar install, then its is probably as others have said the bms is not yet up to speed - It needs a proper charge to 14.4v or so, and then after that you can test the solar better.

Looks like the panels were getting up to 40w at one point, but that wont do a lot to the voltage of an empty battery........

 

[JockandRita]

suavecarve. I don't have the Fogstar App, but I do have the Victron Smart Shunt. Our 610A of LiFePo4 are showing a constant 0.5A drain, taking them down by about 10% a week., (now at 72%) The 320w of solar input shows barely an amp going in at any one time, with the current overcast weather.

I hope that it was the BMS closing down, erring on the side of battery protection, and that plugging in to 240v supply last night has restarted it, and has shown improvements in voltage readings for you.

Cheers,

Jock.

 

[Pausim]

Remaining capacity 141.1%

It also says Current 0AH, current is measured in A (Amps), AH (Amp hours) is a measure of capacity not current flowing.

 

[suavecarve]

How many cycles has the battery done? You need a few for the BMS to calibrate

7.
Some googling suggests you are spot on

 

[suavecarve]

The Fogstar app will only show amps in terms of amps /hr charging or discharging current as reflected by the solar input in the Victron app. I think it has just run itself down. I’m guess you charge to 14.2 or 14.4 v at full. That’s why you will get more in than the advertised number of amps capacity. I think the battery just ran itself too low. I’d trust the shunt and not the Fogstar app. As others say above. It needs a few cycle for the % figure to be dependable.

Your Victron app (solar? Shunt? Don’t have one so not too sure) shows a steady drain, counteracted periodically by solar. What voltage do you consider as being a full battery? When you added the solar, did you connect the controller to the battery first and then connect the panels?

I m pretty neanderthal about what volts I charge to. I charge til it's full of amps.

Connected battery prior to solar to the mppt.

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[suavecarve]

Scores on the doors this morning are charged 240 overnight to within 4 hours of complete charge.
I decided to take out the 240 supply (it will go in again tonight til 100%) as just want to check my new 350 solar against the FiL new 320 solar (without victron but has fogstar 280) on a nice day

I am fairly certain or certainly satisfied it is new BMS settling in

Thanks to all

 

[MichaelT]

I m pretty neanderthal about what volts I charge to. I charge til it's full of amps.

Connected battery prior to solar to the mppt.

Assuming you have a lithium profile charger I would stick that on for a couple of days to full charge it then run something to test solar.

Has it been cold where you are and BMS cut in?

Make sure charging is enabled on fogstar app.

 

[suavecarve]

Assuming you have a lithium profile charger I would stick that on for a couple of days to full charge it then run something to test solar.

Has it been cold where you are and BMS cut in?

Make sure charging is enabled on fogstar app.

I m an impatient sort of guy and been looking forward to checking my solar and the FiLs and today is that day !
I know you are spot on with the advice, but I think that charging it up fully tonight will just put it back 18 hours and solar is free and electricity is cheaper overnight !!!
It hasnt been cold enough for BMS to turn itself off for that reason
I was caught out before on the charging/discharging enablement on the app so have found out about that the hard way ! One of the things I tried whilst on holiday last time was turning the discharging off and back on whilst we had things running from the inverter to see what happened to the output. What happened was a slight popping and no electric. Thinking I had to have blown a fuse the torches had to come out and half an hour of checking everything apart from the blatantly obvious panel which just needed turning on I learnt not to do that again with the amount of earache I got !

 

[Ian_H]

I m pretty neanderthal about what volts I charge to. I charge til it's full of amps.

Connected battery prior to solar to the mppt.

With my fogstar, the bms/app doesn't notice the background drains of tracker and ablemail topping up the starter. So a week after fully charging it still says 100% full. But if I turn on solar or EHU it takes some charging to get up to 14.3V, equivalent to about 1% drain per day. This is why you need to charge until the voltage of about 14.2V is reached and it goes into absorption. Otherwise the error in amphours/soc will just continue to get worse.
I did moan at fogstar about the app graph labels about a year ago, they mentioned an upcoming update but I haven't seen one.

 

[JockandRita]

Scores on the doors this morning are charged 240 overnight to within 4 hours of complete charge.
I decided to take out the 240 supply (it will go in again tonight til 100%) as just want to check my new 350 solar against the FiL new 320 solar (without victron but has fogstar 280) on a nice day

I am fairly certain or certainly satisfied it is new BMS settling inView attachment 977015View attachment 977016

Thanks to all

Glad to see you "back up and running" again.

The sun is up and I'm getting readings I've not seen for about a fortnight now.

Cheers,

Jock.

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[AdrianChen]

I m pretty neanderthal about what volts I charge to. I charge til it's full of amps.

Connected battery prior to solar to the mppt.

Are you happy with the battery settings you have on the solar charger, or are they the default?

 

[AdrianChen]

I m an impatient sort of guy and been looking forward to checking my solar and the FiLs and today is that day !
I know you are spot on with the advice, but I think that charging it up fully tonight will just put it back 18 hours and solar is free and electricity is cheaper overnight !!!

Good day for it! We've actually got some sun this morning!

 

[suavecarve]

Are you happy with the battery settings you have on the solar charger, or are they the default?

Both really. Default and happy (mainly because it's all black magic to me)

 

[Ian_H]

Maybe worth noting that Fogstar talked me through changing the default victron lithium absorption voltages on mains and solar chargers from 14.2V to 14.3V because my battery bms was not resetting to 100% soc. It worked straight away.

 

[Lenny HB]

Maybe worth noting that Fogstar talked me through changing the default victron lithium absorption voltages on mains and solar chargers from 14.2V to 14.3V because my battery bms was not resetting to 100% soc. It worked straight away.

Got mine set to 14.25v, that bit over 14.2 does the trick.

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