Lithium Battery Sizes: Ah, Voltage, kWh, Dimensions

A question about lithium battery sizes is usually three questions at once: how many amp-hours, at what voltage, and how much room it takes. This article answers from the records of the FLA range in Felicity lithium batteries: twelve sizes at three voltages, with each one's energy, dimensions and weight as its record states them, and then a way to choose the size that fits your load.

Products mentioned in this article

Felicity Solar FLA48200 51.2V 10kWh LiFePO4 Battery

• Nominal Energy:10 kWh
• Nominal Capacity:200 Ah

AED 3,745

Order now — Felicity Solar FLA48200 51.2V 10kWh LiFePO4 Battery

Felicity Solar FLA48500 51.2V 25kWh LiFePO4 Battery

• Nominal Energy:25 kWh
• Nominal Capacity:500 Ah

AED 1,310

Order now — Felicity Solar FLA48500 51.2V 25kWh LiFePO4 Battery

Felicity Solar FLA12100 12.8V 1.28kWh LiFePO4 Battery

• Nominal Energy:1.28 kWh
• Nominal Capacity:100 Ah

AED 4,380

Order now — Felicity Solar FLA12100 12.8V 1.28kWh LiFePO4 Battery

Felicity Solar FLA12200 12.8V 2.56kWh LiFePO4 Battery

• Nominal Energy:2.56 kWh
• Nominal Capacity:200 Ah

AED 2,270

Order now — Felicity Solar FLA12200 12.8V 2.56kWh LiFePO4 Battery

Felicity Solar FLA24200 25.6V 5kWh LiFePO4 Battery

• Nominal Energy:5 kWh
• Nominal Capacity:200 Ah

AED 4,060

Order now — Felicity Solar FLA24200 25.6V 5kWh LiFePO4 Battery

Felicity Solar FLA48100 51.2V 5.12kWh LiFePO4 Battery

• Nominal Energy:5.12 kWh
• Nominal Capacity:100 Ah

AED 4,760

Order now — Felicity Solar FLA48100 51.2V 5.12kWh LiFePO4 Battery

A size is three numbers, not one

• Capacity in amp-hours is the number printed on the case: 100, 200, 300.
• Voltage decides which inverter it works with: 12.8, 25.6 or 51.2 V, sold as 12, 24 and 48 V.
• Energy in kWh is the two multiplied, and it is the number that says how many hours it runs your home.

The common mistake is to compare amp-hours alone. A 200 Ah battery at 12.8 V holds 2.56 kWh; a 200 Ah battery at 51.2 V holds 10 kWh. Same printed number, four times the energy.

The 12.8 V sizes

These are sizes for small loads: lighting, fans, a TV, phone charging. The FLA12100 record states up to 16 units in parallel.

The 25.6 V sizes

A 24 V battery goes with a 24 V inverter. The 4 kW IVEM4024-II, for one, states a battery range of 21-31.5 V, so the FLA24200 and its sisters work with it and a 51.2 V battery does not.

The 51.2 V sizes

This is the voltage of home systems: the 5 to 12 kW Felicity inverters named in the ready-made systems state a battery range that starts at 40 or 42 V. The FLA48100 and the FLA48200 mount on a wall or stand on the floor, by their records; the FLA48500 is floor-standing only.

Where amp-hours times volts is not the printed figure

Multiply 200 Ah by 51.2 V and you get 10.24 kWh; the FLA48200 record states 10. Multiply 500 by 51.2 and you get 25.6; the FLA48500 record states 25. We print both figures as they are and do not choose between them. When you size, work with the smaller one, the record's.

Choosing a size from your load

The rule: energy needed = daily consumption × hours on the battery ÷ 24. Then pick a battery that covers it once 90% of its nominal energy is counted as usable, which is what the system calculator does.

• An apartment using 13.8 kWh a day that wants four hours: 2.3 kWh, which the 100 Ah size at 51.2 V covers twice over.
• The same apartment for eight hours: 4.6 kWh, and its system page names the 200 Ah size, the FLA48200.
• A house with no grid using 25.4 kWh: two of the 500 Ah size, as in the off-grid house system.

One large battery or several small ones?

The records allow parallel banks: up to 15 units for the 25.6 and 51.2 V sizes of the FLA range, up to 16 for the 12.8 V sizes. Five 100 Ah batteries give about the energy of one 500 Ah battery, at 48 kg a piece instead of 218 kg in one. Small units are easier to carry and to extend; a large one has fewer connections. Only parallel units of the same model.

What every size shares

Every size in the tables above is LiFePO4, with a depth of discharge of 95% or more on its record, 6,000 cycles or more (8,000 on the FLA48350TG2 record), a charging temperature range of 0 to 55 °C, and CAN and RS485 communication. Size does not change the chemistry; it changes energy, weight and room. Against gel: the G12V200AH gel battery holds 2.4 kWh and weighs 60 kg, where the FLA12200 holds 2.56 kWh and weighs 15 kg. The detail is in the lithium and gel comparison.

Where the rest of the figures are

Each size has a product page with its price and a datasheet, such as the FLA48200 datasheet. The price shown is the price you pay, and orders are collected from our store in Dubai or Riyadh. Before buying, measure the space: dimensions in the tables are in the order the record gives them, width, height, depth.