Battery Problems

[Kelvin8tor]

Around about a year ago I upgraded the 12v system on my motorhome changing to a lithium battery
280 amp Fogstar drift battery
Renogy 30 amp battery to battery charger with 300 watts of solar
Renogy 2000 watt inverter
Every thing has been working fine although I only ever used around 50% of the battery
Use is normally microwave kettle and charging bike batteries phone batteries
I have during the last couple of trips powered the fridge through the inverter
I have been away for a few days and decided to get full use out of the battery so during the day I have had the fridge powered through the inverter and when monitoring the apps both Fogstar and Renogy the battery was discharging at around 2.5-3.6 amps due to the solar generated
The battery had dropped to around 42% this afternoon and being as we are heading back home tomorrow I continued to use the inverter then suddenly the inverter alarm came on and the fridge lit up on the gas the Fogstar app reported over discharge and shut down the Renogy app reported the same over discharge of leisure battery
Not sure what happened as the battery should still have plenty of power
The renogy app has shown the minimum voltage today at 8.9 volts maximum today of 13.8
The Fogstar app is allowing discharge at the moment ( could not turn that on earlier ) voltage is currently 11.2 but no sun at the moment so no more charging cell voltage low 2.759 Hi 2.834 Diff 0.075
Any ideas
Thanks

 

[RogerIvy]

How long since the battery was at 100% Soc?
Bear in mind the FS BMS doesn’t accurately detect small (<0.7A) drain which can add up over long periods of time.

 

[Kelvin8tor]

How long since the battery was at 100% Soc?
Bear in mind the FS BMS doesn’t accurately detect small (<0.7A) drain which can add up over long periods of time.

The battery was at 100% a few days ago

 

[RogerIvy]

In theory a 3A draw will deplete your 280 in about 93 hours.
Is it possible that something else used up the power?

Interestingly today I chased down a 3A draw caused by a faulty after market van stereo system. The installer took a feed from the TV wire, and something has gone wrong with the unit.

 

[herald_400rl]

How long since the battery was at 100% Soc?
Bear in mind the FS BMS doesn’t accurately detect small (<0.7A) drain which can add up over long periods of time.

Hello, is the battery status source of truth on (for example) a Victron shunt based on telling the shunt the battery initially fully charged?

^{_{Subscribers  do not see these advertisements}}

 

[RogerIvy]

If both BMS and Smartshunt are correctly set up they will both accurately register a full state of charge. The shunt does it by detecting current flow and voltage, and the BMS does it by detecting individual cell voltage.

 

[Kelvin8tor]

If both BMS and Smartshunt are correctly set up they will both accurately register a full state of charge. The shunt does it by detecting current flow and voltage, and the BMS does it by detecting individual cell voltage.

I don’t have a smart shunt I only have the Fogstar app to indicate the soc perhaps this is totally inaccurate

 

[RogerIvy]

I don’t have a smart shunt I only have the Fogstar app to indicate the soc perhaps this is totally inaccurate

When all is well you don’t need a shunt, but I guess when you need to debug it’s really handy. I’d consider fitting one if I was you.

 

[Kelvin8tor]

I am hoping that the battery will recharge tomorrow on the drive home I do have a lithium battery charger at home that I purchased from Fogstar when I purchased the battery
I do not use the mains charger in the Motorhome as it has no lithium setting

 

[RogerIvy]

I am hoping that the battery will recharge tomorrow on the drive home I do have a lithium battery charger at home that I purchased from Fogstar when I purchased the battery
I do not use the mains charger in the Motorhome as it has no lithium setting

If your charger has an AGM setting it will probably be OK. Not optimal but OK.

^{_{Subscribers  do not see these advertisements}}

 

[Kelvin8tor]

When all is well you don’t need a shunt, but I guess when you need to debug it’s really handy. I’d consider fitting one if I was you.

Maybe I should purchase one any recommended that would integrate with my current system

 

[RogerIvy]

Maybe I should purchase one any recommended that would integrate with my current system

I’d recommend Victron. The 300A, 500A or the BMV 712 (it has a small round display).

 

[Kelvin8tor]

If your charger has an AGM setting it will probably be OK. Not optimal but OK.

Don’t often use sites with a hook up so never been to worried about the on board charger

 

[Kelvin8tor]

I’d recommend Victron. The 300A, 500A or the BMV 712 (it has a small round display).

Would you have a link to this product.

 

[Kelvin8tor]

Is the Renogy smart shunt any good?

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

If your charger has an AGM setting it will probably be OK. Not optimal but OK.

I'll have to disagree with that Roger, most AGM chargers charge at 14.7v which is a bit too high.

 

[Lenny HB]

I don’t have a smart shunt I only have the Fogstar app to indicate the soc perhaps this is totally inaccurate

When my van is sitting the drive with just low current draw from the batteries the Fogstar BMS can read 20% higher than my Victron shunt, the shunt is the accurate reading.

 

[RogerIvy]

Would you have a link to this product.

Victron Energy SmartShunt 300 amp Battery Monitor (Bluetooth) — Offgrid Power Solutions

The SmartShunt is an all in one battery monitor, only without a display. Your phone acts as the display. The SmartShunt connects via Bluetooth to the VictronConnect App on your phone (or tablet) and you can conveniently read out all monitored battery parameters, like state of charge, time to go, his

offgridpower.solutions

 

[LithiumConvert]

If your charger has an AGM setting it will probably be OK. Not optimal but OK.

I'll have to disagree with that Roger, most AGM chargers charge at 14.7v which is a bit too high.

0.3 volt above the recommended voltage for my Sterling Power batteries.