Battery bank capacity

Hi Everyone

I am looking for some help on two questions please

1, I have 4 260ah AGM 12v batteries connected to give me 48v and i have 4 of these banks all going back to the Victron power in busbar, how do I work out the capacity to enter into the capacity box on the Victron system,

2, what should I set the cut off voltage to as I believe I should not discharge AGM batteries lower than 50%, also where in the system is this setting to? my system shuts the batteries off and goes back to grid when it gets to 70% even when I set it to 50% in the ESS section, I do have it set to “Optimized (with batter life)”

Thanks for any help

Hello.

  1. Capacity is 260AH x 4. Confirm you mean you have 16 batteries in total?

  2. You can shut down on SOC (i assume you mean in case of grid faliure). But the shut down can be overriden by the c ratings in ESS assistant. So what are they?

Thanks for the reply
Yes 16 260ah batteries in total (4x sets of 4)

2, I have the grid, solar and batteries connected, in the summer there is no issue but in the winter when there is not much sun I would like to use solar first to supply the house and charge the batteries and then at night use the batteries dropping to no lower than 50% and only then use the grid power.

So 1040Ah bank capacity.

This is what ESS does, however I do have a word of caution.
Lead based batteries do not like to be held down at a low SOC. They should really be kept charged during cloudy days and darker months especially if you don’t expect them to be fully charged each day.

You have the first step correct- not to cycle too low; however the big mistake i see alot of lead owners make is also not charging correctly.

To be honest the last couple of months I have changed the setting to “Keep batteries charged” so should not be a problem, I was just wondering why they wont discharge lower than around 70% so thought I may have something set wrong,

My main question was regarding what I should put in the capacity box with me using 16 batteries?

1040AH

There can be a few factors.
Ess dynamic cut off is possibly an issue.
Unless SOC calculation is wrong?
How balanced are the batteries in each row of 48v? That can also eat capacity.

They are all balanced, I have a battery balancer fitted to each bank,
SOC wrong? remind me where this is and what it should be?

Thanks again for this advise

Excellent.

Are you using the ve bus SOC? (State of charge) You aren’t using a shunt?

Hi

Yes I have the shunt installed after the Victron power in