Illustrative worked example. The inputs are assumptions, not a customer project. The arithmetic is real.
The scenario
A process plant needs to keep a 24 V control panel running during outages. The load is 10 A and the target is 8 hours.
Energy needed
24 V × 10 A = 240 W. Over 8 hours that is 1,920 Wh, or 1.92 kWh. If 90% of the battery is usable, the nominal energy is about 2.13 kWh.
Choosing the configuration
- Cells. Eight LiFePO₄ cells in series make 25.6 V nominal, the 24 V class.
- Capacity. A 100 Ah pack at 25.6 V holds 2.56 kWh, above the 2.13 kWh needed.
- Alternative. A 12 V (12.8 V) system would draw 20 A for the same power, so the cables and fuses would need to be heavier.
- Charger. The charger or DC supply must match the 25.6 V pack.
What Eldtek confirms
- The voltage window of the panel against the pack's range.
- Charger and BMS communication.
- Temperature and mounting conditions.
- Expected life at the daily cycling pattern.
See the battery energy storage systems page for the full range.
Frequently asked questions
How many amp-hours does a 24 V, 10 A load need for 8 hours?
About 80 Ah of usable capacity, or roughly 89 Ah nominal at 90% usable depth of discharge. A 100 Ah pack covers it.
Why use 24 V rather than 12 V?
For the same power, 24 V draws half the current of 12 V, which allows thinner cables and lower losses.
Have a similar requirement?Send your figures and an Eldtek engineer will size it for your site.
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