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Apparently, as part of the setup, you can enter your battery capacity (in my case, 210Ah).
Every time the charging current drops to a low value, the battery is deemed as being fully charged and the charging status is set to 100%.
It sounds as if, even if your battery capacity has dropped to,say, 50Ah, the monitor will still say 100%.
How can you see that your battery has lost capacity?
The BMV and shunt count how many amp hours are drawn or put back into your battery.
To establish how many amp hours it considers a battery to be when full, one must first set the capacity value, which in your case is 210ah.
You should then synchronize the BMV when your battery is fully charged so that it can keep track of ah being drawn or put back into the battery from then on.
Your capacity (ah remaining) will then be calculated and displayed by the BMV based on usage.
Remember that different battery types have different acceptable discharge thresholds with regard to lifespan.
Some people like to trick the BMV by say cutting the capacity figure in half for FLA batteries so that the BMV will read Zero ah remaining when the batteries have reached half their capacity.
If you have a Lithium bank with discharge protection built in, the batteries will disconnect when they reach a low voltage threshold. If you find you are unable to use their full capacity, you could note the ah value when this happens and adjust the settings accordingly so that the BMV will accurately alert you when you are close to depleting the bank.
You will see it when discharging.
Interesting and thanks for your info, Solgato.
A year later..
Even with my new Victron BMV 700, my two one year old service batteries (450Ah total) are still now registering as 95% full but unable to provide 12v at a 10A load.
I'm not happy with the BMV 700, as it hasn't really helped. It hasn't predicted this and still believes the battery is 95% full when it is clearly pretty much ka'duk.
It seems to me that then BMV should also be able to register a low voltage when there is a low current draw and synchronise the battery as empty. Since it already knows between the 100% and 0% how many Ah have been provided or charged, it should be able to give you an ACTUAL battery capacity, which the user could monitor over the months.
This would be a real winner.
As it is now, it is a real misser.
We call that in English. "Spoiling the ship for a ha'pth of tar"
