Depth of Discharge Calculator for Batteries

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Depth of Discharge Calculator

Estimate battery DoD, remaining usable energy, runtime to reserve, and cycle stress for home backup, solar, UPS, and smart home power packs.

🔋Real Battery Presets

⚙Battery and Load Inputs

Used for recommended DoD, efficiency, and cycle stress.
Use pack nominal voltage, not charger voltage.
Enter the label capacity at the rated discharge rate.
The SoC before the load runs.
Depth of discharge is the SoC drop from the start point.
Runtime is calculated only down to this reserve floor.
Use measured watts for inverters, hubs, cameras, routers, or loads.
DC loads may be 95-99%; inverter systems are often 85-94%.
Use 90 for a pack that now holds roughly 90% of rated capacity.
Approximate capacity correction for practical planning.
Depth of discharge is the percentage of usable battery capacity removed. For battery life planning, compare the calculated DoD with the chemistry recommendation and the reserve floor your system needs.
Depth of Discharge
0%
SoC drop
Energy Used
0 Wh
removed from battery
Usable Energy Left
0 Wh
above reserve floor
Runtime to Reserve
0 h
at selected load
Enter your pack details and calculate.

📊Selected Battery Spec Grid

1280
Rated Wh
1280
Effective Wh
80%
Daily DoD Guide
3000+
Typical Cycles

📘Depth of Discharge Reference Tables

Battery chemistry Common daily DoD Occasional deep DoD Typical cycle range Planning note
LiFePO4 lithium iron phosphate 70-80% 90% 3000-6000 cycles High usable capacity with a BMS cutoff usually below the user reserve.
Lithium ion NMC or NCA 60-80% 90% 800-1500 cycles Cycle life improves when full charges and very deep discharges are limited.
Flooded lead acid deep cycle 40-50% 80% 500-1200 cycles Repeatedly going below 50% SoC shortens service life quickly.
AGM sealed lead acid 40-50% 80% 300-900 cycles Good standby behavior, but deep cycling still costs cycle life.
Gel sealed lead acid 40-50% 75% 400-1000 cycles Prefers controlled charge voltage and moderate discharge depth.
Small SLA standby battery 30-50% 80% 200-600 cycles Alarm and UPS packs are often sized for reserve, not frequent deep cycles.
12V lead acid rest voltage Approx SoC Depth used from full 24V bank equivalent 48V bank equivalent
12.73 V 100% 0% DoD 25.46 V 50.92 V
12.50 V 80% 20% DoD 25.00 V 50.00 V
12.24 V 60% 40% DoD 24.48 V 48.96 V
12.10 V 50% 50% DoD 24.20 V 48.40 V
11.96 V 40% 60% DoD 23.92 V 47.84 V
11.66 V 20% 80% DoD 23.32 V 46.64 V
Common battery setup Rated energy Healthy daily use Typical reserve floor Good for
12.8V 100Ah LiFePO4 1280 Wh 900-1020 Wh 10-20% SoC Router, lights, small fridge controller, camera NVR
51.2V 100Ah rack LFP 5120 Wh 3600-4100 Wh 10-20% SoC Whole home network, automation panel, sump control
12V 18Ah AGM UPS 216 Wh 85-110 Wh 50% SoC Modem, router, hub, ONT, small PoE switch
24V 225Ah flooded bank 5400 Wh 2160-2700 Wh 50% SoC Cabin DC system, inverter backup, solar shed
52V 14Ah NMC pack 728 Wh 440-580 Wh 15-25% SoC Mobile gear, e-bike pack testing, portable DC loads
Load example Average watts Daily energy 5120Wh LFP runtime 1280Wh LFP runtime
Router, modem, smart hub 25 W 600 Wh/day 5.5-6.8 days 1.4-1.7 days
PoE switch plus 4 cameras 65 W 1560 Wh/day 2.1-2.6 days 12-16 hours
Network rack and NAS idle 140 W 3360 Wh/day 23-29 hours 6-7 hours
Backup lighting circuit 180 W 4320 Wh/day 18-23 hours 4-5 hours
Mixed outage essentials 350 W 8400 Wh/day 9-12 hours 2-3 hours

💡Depth of Discharge Tips

Use SoC drop for DoD. A battery that starts at 100% SoC and ends at 45% SoC has a 55% depth of discharge. If it starts at 80% and ends at 35%, that cycle is 45% DoD.
Reserve is not wasted energy. Keeping a 10-20% lithium reserve or a 50% lead-acid reserve protects battery life and leaves margin for inverter cutoff, cold weather, and measurement error.
This calculator estimates planning values from nominal voltage, rated Ah, capacity derates, and average load. Battery monitor readings and manufacturer limits should guide final operating settings.

When you utilize a battery system, you have to understand the differance between the capacity of the battery and the usable energy of the battery. Many peoples will assume that if the battery has a 100Ah capacity, then the battery can provide 100Ah of usable energy. However, batteries cannot be used as fuel tank for vehicles, for instance.

When you draw energy from a battery, the depth of discharge of the battery decrease. The depth of discharge is a measurement of the energy removed from the battery compared to the total capacity of the battery. Thus, if you have a battery with 100 percent of the energy within the battery, and you use 30 percent of the energy from that battery, then the depth of discharge will be 30 percent, but the state of charge will be 70 percent.

Battery Capacity and Usable Energy

Furthermore, as batteries experience a depth of discharge, the chemical reaction within the battery are stressed out. The more the depth of discharge of the battery decreases, the more chemical stress is place upon the battery. The chemistry of the battery will determine how deep you can discharge the battery.

For instance, lead-acid and AGM batteries should not experience a depth of discharge beyond 50 percent. If lead-acid batteries experience a depth of discharge beyond 50 percent, the lead acid batteries will experience a permanent loss of their capacity. Therefore, if you utilize lead acid batteries, you will have to purchase batteries that contain twice the capacity of what you think that you require.

In contrast, lithium batteries, specifically LiFePO4 batteries, can better handle deep discharges. Such lithium batteries can have 80 or 90 percent of their capacity utilize without damaging the battery. However, as with any other battery, there is a limit to the depth of discharge for the lithium batteries.

If the depth of discharge of the battery goes beyond that limit, then the battery will begin to fail. Beyond the chemistry of the batteries, there is also energy loss that must be considered. For instance, all inverter will lose some of the energy of the battery as heat.

Thus, you will lose energy to the inverter. Another factor that will reduce the amount of energy that the battery delivers is the temperature at which the batteries are being use. When you use batteries in cold environments, the chemical reactions within the batteries will occur at a slow rate.

Thus, the battery will deliver less energy if it is within a cold environment. For instance, a battery that can provide 100Ah at room temperature may only be able to provide 70Ah in a cold environment. In addition to these factors, you must create a floor for the battery’s state of charge so that the battery does not experience a depth of discharge to 100 percent (or a state of charge of 0 percent).

While there are Battery Management Systems in place to prevent this from occurring, you should not solely rely upon them. A manual floor should be created at 10 or 20 percent of the batteries capacity to account for any error in the systems measurement of the batteries state of charge. Finally, you must consider the age of the batteries when calculating the usable energy of the batteries.

Batteries are consumable item; over time, they will lose their ability to hold as much energy as they are rated for. For instance, a battery that is three years old may only hold 90 percent of the energy that it could hold when it was new. Thus, if you calculate the energy requirement of a system based off the original design capacity of the battery, the battery will provide less energy than is calculated.

Therefore, you should factor the age of the battery into energy calculations so that a realistic expectation of the energy that the battery will provide can be made. Through consideration of each of these factor, the battery can be made a reliable tool in fulfilling the energy need of a system.

Depth of Discharge Calculator for Batteries

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