Fogstar potential issues?

[Salty Spuds]

Hi all
Not sure if my leisure battery set up is working correctly or the Fogstar app is faulty.
So 12 months ago, I upgraded our leisure battery to a Fogstar drift 105ah with an Ablemail AMT12-2 to maintain the starter battery. The starter battery was replaced under warranty by VW in October 24 (Moll). The charger is a Sterling BB1230, set to LifePo4, and we have solar Epever mppt.
All year everything seemed to be working fine. The Fogstar app showed us the capacity, voltage etc commensurate with usage or charging and the Ablemail seemed to keep the starter with enough charge ready for use. There is also a battery monitor on the starter so we can check.
All this gave me confidence that I didn’t need to keep checking everything was working properly. We don’t use the van often but camped out late November without issues battery wise and I gave it a run on the 6th of December, again no signs of issues.
So I checked the starter monitor yesterday and found it had only 3% but with 12.02v. The Ablemail usually doesn’t let it drop below 20%. So I checked the Fogstar app and it said 100% but the voltage was 11v. This morning I put my Noco 5a onto the starter and began charging. The monitor app showed the capacity going up as expected. I then checked back with the Fogstar app and it showed 0% capacity! So it looks like the leisure battery has fully discharged but the app said 100%, and only once I had begun charging the starter did it alter.
I’ve plugged in our Fogstar charger to charge the leisure battery and so far it appears as it’s charging okay but I’m worried that the app has given false information about the levels and damaged it.
Nothing was left on in the van either, so master switch off and the fridge was also off.
I’ve added some screenshots from this morning so if anyone has any ideas I’d like to hear them please.
Cheers
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The BM2 battery monitor default SOC chart is for a flooded cell battery and gives a false reading for an AGM battery. I’m assuming your starter is an AGM. You can adjust the default SOC chart to suit your battery. Also don’t forget that a stop/start battery will generally only be around 80% charged.
This is a typical AGM battery SOC chart, your battery is around 50% charged, not 3%.

 

[airhoguk]

So a Victron 75/15 or 100/20 will cope with your current panel setup. Personally I’d go for the 100/20 to give you a bit of redundancy for the future

 

[PJ134]

@Dellmassive Not sure if this is relevant, but the Noco 5 has been charging the starter battery (Moll) for over 24 hours. The BM says it’s fully charged but the Noco shows it isn’t as the green light hasn’t been reached.
Cheers
0

 

[PJ134]

So a Victron 75/15 or 100/20 will cope with your current panel setup. Personally I’d go for the 100/20 to give you a bit of redundancy for the future

Thanks @airhoguk , I’ll have a look at getting one. Would it be a case of just swapping them over or is the wiring likely to be different? Do I need to isolate or cover over the panels whilst installing?

 

[PJ134]

The BM2 battery monitor default SOC chart is for a flooded cell battery and gives a false reading for an AGM battery. I’m assuming your starter is an AGM. You can adjust the default SOC chart to suit your battery. Also don’t forget that a stop/start battery will generally only be around 80% charged.
This is a typical AGM battery SOC chart, your battery is around 50% charged, not 3%.
View attachment 312747

The starter battery was replaced by VW under warranty in October 24 and it’s a Moll EFB+.
Cheers

 

[Dellmassive]

I thought the Ablemail would only charge the SB if the LB was at a healthy voltage?

EDIT: the instructions say the LB has to be at least 13V or it won’t trickle charge the SB, so the Ablemail shouldn’t be the problem.

Yes. That's correct... It will stop when the LB gets low.

Assuming your AMT12-2 is on profile4 default......

The LB needs to be above 13.0v and the starter needs to be below 12.4v.

But, there is also a mention of 11.4v and 11.7v

...

 

[Dellmassive]

https://ablemail.co.uk/wp-content/uploads/2024/11/AMT12-2.pdf

 

[roadtripper]

The starter battery was replaced by VW under warranty in October 24 and it’s a Moll EFB+.

AGM and EFB are essentially the same for charge profile, neither are a standard flooded battery.

If you get it changed again press them for an AGM battery, EFBs are not as reliable or long lived, especially the Moll ones which have a not great track history on the forum.

 

[DXX]

Best to consult the battery manufacturers technical data for SOC / Voltage chart, each battery is different. Using generic charts or app’s is just an estimate.

 

[airhoguk]

Thanks @airhoguk , I’ll have a look at getting one. Would it be a case of just swapping them over or is the wiring likely to be different? Do I need to isolate or cover over the panels whilst installing?

Cover the panels so they aren’t yielding any sun, a thick blanket will do. Connect the battery side first then the solar otherwise you could blow the non replaceable fuse in the mppt (I learnt the hard way for my sins)

 

[PJ134]

Cover the panels so they aren’t yielding any sun, a thick blanket will do. Connect the battery side first then the solar otherwise you could blow the non replaceable fuse in the mppt (I learnt the hard way for my sins)

Thanks for this, much appreciated. I’ll get the smart version so I can use the app. I think I’ll get a Victron B2B to replace the Sterling as well. I’m looking at the Orion TR 12-12-30 Smart, do you think that is suitable?
Cheers.

 

[Skyliner33]

Thanks for this, much appreciated. I’ll get the smart version so I can use the app. I think I’ll get a Victron B2B to replace the Sterling as well. I’m looking at the Orion TR 12-12-30 Smart, do you think that is suitable?
Cheers.

The Orion 30A runs notoriously hot. If getting new equipment I would advise getting the 50A Orion XS. A far better charger.

 

[PJ134]

Happy New Year to you all
A quick update.
I’ve purchased a Victron SmartSolar 100/20 and a Victron Orion XS 12/12/50 which once installed should hopefully solve the Fogstar POV issues.
This morning the FS hasn’t lost much capacity with the fridge on which is understandable with the ambient temperature.
I’m wondering if I still need to drain it which without an inverter will take an age, as the cells look almost identical now? Screenshots of the readings below.
Cheers everyone.