Victron and AGM battery charge

Fishinbrine

Senior Member
VCDS User
VIP Member
T6 Pro
Evening all!
I may be being over cautious here but.....
I have a 95ah AGM leisure battery, 4 or 5 months old and changed out my Sterling b2b charger at the same time to mover over totally to Victrin except for the Sargent panel (I disabled the charger when on EHU)

Anyway.... Considering the great amount of sunlight I have and ignoring my relatively low use regarding driving my leisure battery state of charge I consider low at 77%

Could there be something amiss possibly? Only loads in the van is the fridge which I appreciate will be working harder in this weather but it's generally always maintained close to 100% and was near enough there on a return from France 2 week ago.

If anyone can shed any light on this or advise a potential setting I have incorrect I will be very grateful 😁

Screenshot_2025-08-13-17-36-04-97_30b6efbd53acd6f273baafa7ca03da38.webp

Screenshot_2025-08-13-17-36-42-78_30b6efbd53acd6f273baafa7ca03da38.webp

Screenshot_2025-08-13-17-36-56-21_30b6efbd53acd6f273baafa7ca03da38.webp

Screenshot_2025-08-13-17-37-16-47_30b6efbd53acd6f273baafa7ca03da38.webp

Screenshot_2025-08-13-17-37-47-16_30b6efbd53acd6f273baafa7ca03da38.webp
 
Are you talking about purely using solar for your leisure battery? You got 225Wh from solar yesterday. If we say that a fridge draws 3.5A when the compressor is on, then it's energy consumption over 24 hours ( lets assume it's on for 12 hours) is going to be 3.5 * 12 * 12 = 504 Wh.

So solar on its own not sufficient for the fridge and that isn't counting anything else 12V connected to the leisure battery. Your usable energy on a 95Ah AGM battery is of the order of 550Wh, so (again assuming you are relying purely on solar) I'm not surprised you are only at 77%.
 
Last edited:
I’m not quite sure what you’re telling us. Are you saying that your LB is only charging to 77% Soc? And if so, where are you getting this figure from, I can’t see it in any of your screenshots (I might be missing something)
 
Thanks, yeah, just the fridge running off the leisure battery - none of the other 12v items in use (it's my daily also)
Yeah I suppose that makes mathematical sense, it's just confused me as always sat at around 93-100% until just recently.
I will be upgrading to lithium at some point to have more usable energy once I've had the use from this AGM.
From the screenshots does everything look about right?
 
I’m not quite sure what you’re telling us. Are you saying that your LB is only charging to 77% Soc? And if so, where are you getting this figure from, I can’t see it in any of your screenshots (I might be missing something)
Apologies

Screenshot_2025-08-13-17-35-43-19_30b6efbd53acd6f273baafa7ca03da38.webp
 
Your solar isn’t providing much power, what wattage is it?

Your B2B is only charging at 12w, have you set it to that rather than a higher output? 50A is arguably too high for your size battery.

The shunt details show the LB has been down to 9.99v, if this is the case it may well have suffered some damage.

Ultimately, at the moment your charging isn’t keeping up with the fridge. So, bigger solar panel, higher B2B power and check for battery damage.
 
  • Like
Reactions: CAB
Your solar isn’t providing much power, what wattage is it?

Your B2B is only charging at 12w, have you set it to that rather than a higher output? 50A is arguably too high for your size battery.

The shunt details show the LB has been down to 9.99v, if this is the case it may well have suffered some damage.

Ultimately, at the moment your charging isn’t keeping up with the fridge. So, bigger solar panel, higher B2B power and check for battery damage.
B2B charger is charging at 12a I reduce this to 6 or 8 when driving long distances, it is indeed a 50a B2B charger but that was more in preparation for a lithium upgrade at some point. Yes the 9.9v alarm occured in France when leisure battery dropped to approx 50% when I forgot to connect my mains charger when I was on EHU 🙄

Solar panel - honestly I have no idea of wattage of the panel on the roof at all! I guess I probably should but I don't know why I don't either! The Victron MPPT 75/10 is, I believe only for smaller panels so nothing too big. Maybe a solar upgrade once on lithium would also be a good idea.
 
Yes the 9.9v alarm occured in France when leisure battery dropped to approx 50% when I forgot to connect my mains charger when I was on EHU 🙄
That may be part/all of the problem. 9.9v is totally flat, not 50% which is 12v, so it’s possible your battery is damaged. Maybe worth testing it to see if it’s ok.
 
  • Like
Reactions: CAB
B2B charger is charging at 12a I reduce this to 6 or 8 when driving long distances, it is indeed a 50a B2B charger but that was more in preparation for a lithium upgrade at some point. Yes the 9.9v alarm occured in France when leisure battery dropped to approx 50% when I forgot to connect my mains charger when I was on EHU 🙄

Solar panel - honestly I have no idea of wattage of the panel on the roof at all! I guess I probably should but I don't know why I don't either! The Victron MPPT 75/10 is, I believe only for smaller panels so nothing too big. Maybe a solar upgrade once on lithium would also be a good idea.
Why do you adjust the charging current? That charger should reduce the current automatically as the battery becomes charged. (i.e bulk to absorption to float)
 
Back
Top