Battery chemistry & storage

Depth of discharge vs cycle life calculator

Enter your battery's rated cycles and the depth of discharge it was tested at. See your adjusted cycle life at any target depth, plus a full breakdown across the range.

Your numbers

1 Project details Optional
Shown on your exported report. Leave blank to skip.
2 Your battery
From the datasheet.
The DoD the rated cycle count was measured at.
3 Your target usage
The depth you actually plan to cycle to.
Adds a years-of-service estimate to the results.
Adds a usable energy per cycle figure to the results.

How it works

Three steps to see the full DoD tradeoff

Step 1

Find your rated cycle count and its test DoD

Most datasheets list a cycle rating alongside the depth of discharge it was tested at, commonly 80%. Both numbers are needed to adjust for a different target depth.

Step 2

Set your actual target depth of discharge

Add cycles per week and capacity for a fuller picture, including years of service and usable energy per cycle at your target. The charge rate vs lifespan tool covers a related variable worth checking alongside this one.

Step 3

Scan the full breakdown table for the best tradeoff

Compare cycle life across the full range from 100% down to 10% depth of discharge to find where usable energy and service life balance out for your situation, then check the cycle count to years converter for a second opinion on your chosen depth.

Understanding your depth of discharge tradeoff

Why depth of discharge is the biggest lever you control

Chemistry and manufacturer set a battery's baseline cycle life, but depth of discharge is the one variable a homeowner adjusts directly, simply by choosing how far to run the battery down before recharging. A battery rated for 6,000 cycles at 80% depth of discharge can deliver closer to 9,600 cycles if run at 50% instead, without any change to the hardware, a relationship NREL's energy storage research has characterized as one of the strongest single predictors of real-world cycle life across chemistries.

The real tradeoff: less energy per cycle, more total cycles

Running shallower cycles delivers less usable energy each time, so getting the same total energy over the battery's life often means starting with a slightly larger bank, a tradeoff the oversizing for future battery calculator can help you plan for from the start rather than discovering the gap later. The capacity over time calculator factors this same depth-of-discharge relationship into a full year-by-year capacity projection.

Why the relationship isn't perfectly linear in the real world

This calculator uses a simplified inverse relationship as a planning approximation, but real cycle life curves from manufacturers often show diminishing returns below about 20% depth of discharge, where calendar aging and other wear mechanisms start to dominate over pure cycle stress. The discharge rate vs lifespan tradeoff tool covers a related variable that compounds with depth of discharge, and the battery lifespan estimator is a good independent check if you want a second projection that isn't built on this same simplified curve.

What to check next

Once you've settled on a target depth of discharge, run it through the cycle count to years converter using your actual cycling frequency, or compare chemistries directly with the LFP vs NMC cycle life comparison. This same depth-of-discharge tradeoff factors into how the DOE's Office of Electricity evaluates operating strategies for extending grid-scale storage asset life.

Questions

Frequently asked

A battery rated for 6,000 cycles at 80% depth of discharge delivers roughly 9,600 cycles if cycled at 50% depth of discharge instead, since shallower cycling puts less stress on the cells. Cutting depth of discharge in half roughly doubles the number of cycles delivered.

A shallower depth of discharge trades some usable energy per cycle for a much longer service life, which can lower the effective cost per kWh delivered over the battery's full lifespan. Oversizing a battery bank slightly and running it at 50% instead of 80% depth of discharge is a common way to extend service life without changing chemistry.

This calculator uses a simplified inverse relationship, where halving depth of discharge roughly doubles cycle life, which is a common industry approximation rather than an exact physical law. Real cycle life curves vary by manufacturer and cell chemistry, and often show diminishing returns at very shallow depths of discharge below 20%.

Most residential LFP systems run between 80% and 90% depth of discharge day to day, balancing usable capacity against cycle life. Lead acid systems are typically kept closer to 50% depth of discharge to avoid sharply shortening an already limited cycle life.

Related tools

Keep planning your battery's life

Cycle count to years converter Capacity over time calculator Discharge rate vs lifespan tradeoff Charge rate vs lifespan tradeoff LFP vs NMC cycle life comparison Degradation vs usage pattern Battery state of health calculator All battery chemistry tools