Hi
My lithium ng 200ah batteries are fully charged and since I have had to return the BMS for a warranty issue they may sit in this state for a few weeks and I have no means to discharge them. If I sit the on the blue Smart in storage mode does it matter that they are at 100%?
Alternatively what can I do the discharge them to say 60% safely?
Do not put the charger on the batteries without a BMS, there will be no protection. Even if the charger is set at storage, the batteries will stay full, it does not discharge them to storage. If you have no means of safely discharging them then you will have to let them sit disconnected for a while without manual intervention.
If you know they are full to 100% and want to take them down, no need to go to 60% (myth from other lithium battery types), you just need to take the top of the charge off. The manual says for storage to have them almost full, Section 5.4 of the manual.
When leaving the system unattended for some time, either keep the batteries charged or make sure they are (almost) full and then disconnect the DC system from the battery.
If they are 12V you could connect an old fashioned filament car headlight bulb (50 to 60W, 4 to 5A) and let that run for 2hrs for each battery to discharge 10Ah (5% SOC) under supervision, but you will ruin your batteries if you leave it on for too long.
When you say take the top of the charge off…. You mean discharge them slightly ?
Yes, just discharge them from 100% to say 95%, you only need that top few % removed, no need to go down to 60%.