बैटरी बैंक कैलकुलेटर

How this is calculated#

The tool sizes a battery bank in ampere-hours for a set of loads. It reads no table, so it cites no clause.

1. Inputs. You enter each load in watts with its hours of use. You also enter the system voltage and the depth of discharge. Then you enter the inverter efficiency, the temperature factor and the days of autonomy.
2. Energy per day. For each load, it multiplies the power by the hours of use. It adds the loads.
3. Charge per day. It divides the daily energy by the system voltage and by the inverter efficiency. The result is the daily charge in ampere-hours.
4. Required capacity. It multiplies the daily charge by the days of autonomy and the temperature factor. It then divides by the depth of discharge.

The depth of discharge is the share of the battery you allow to be used. A lower value gives a larger bank. The temperature factor is 1 at normal temperature. A value above 1 adds capacity for a cold site.

Worked example#

• A 48 V bank for two loads. The loads are 500 W for 4 h and 120 W for 24 h. The depth of discharge is 0.5 and the inverter efficiency is 0.9. The energy per day is 4,880 Wh. The charge per day is 112.96 Ah. The required capacity is 225.93 Ah.

Limits#

The tool gives capacity only. It does not choose a battery chemistry, a charger or a cable. For the cable between the bank and the inverter, use the DC cable size calculator.

The result assumes the loads are the same each day. It does not model charging from solar or the grid. It does not model battery ageing or a changing discharge rate. For a home battery with an inverter and solar, use the home battery tool.

The tool uses one system voltage for the whole bank. A 24 V bank and a 48 V bank hold the same energy but give different amp-hours. Take the depth of discharge from the battery maker. It differs between chemistries.

See also: Battery bank for three days of autonomy, Off-grid battery bank at 48 V and Home batteries and AS/NZS 5139.