Battery Cycle Aging Calculator

Estimate capacity loss from cycling, heat, and usage patterns. Compare chemistries and scenarios quickly side-by-side. Export reports, track trends, and plan maintenance schedules today.

Calculator Inputs

Used to set typical degradation sensitivities.
Reference: ~25°C, 1C, 100% DoD, mid SOC.
Higher C-rate increases internal heating and stress.
Higher average SOC generally accelerates aging.
Simple stress relief heuristic (not chemistry-specific).
Conservative buffer subtracted from remaining capacity.
Tip
If you already ran a calculation, the export buttons above will download that latest result.

Example Data Table

Sample scenario inputs and typical outputs for quick reference.
Scenario Chemistry Cycles DoD (%) Temp (°C) C-rate Calendar (mo) Remaining (%) Notes
EV moderate NMC 600 80 30 1.0 18 ~82–90 Balanced usage with mild heat exposure.
Hot fast-charge NCA 450 90 40 2.0 12 ~70–85 Heat and high rate accelerate cycle fade.
Stationary gentle LFP 1200 60 25 0.5 24 ~80–92 Lower stress supports longer cycle life.
Ranges are illustrative. Use the calculator for consistent assumptions.

Formula Used

1) Cycle aging
N_eff = N · f(DoD) · f(C-rate) · f(Temp) · f(SOC) · f(Rest)
Q_loss_cycle = 0.20 · (N_eff / N80_ref)^b
  • N80_ref is your “rated cycles to 80%” at reference stress.
  • b depends on chemistry (typical 0.55–0.72).
  • f(Temp) uses a Q10 rule: ~2× per +10°C.
2) Calendar aging
Q_loss_cal = k_cal · sqrt(t_months) · f(T_storage) · f(SOC_storage)
  • Square-root time behavior is common in simplified diffusion-limited models.
  • k_cal depends on chemistry family.
  • Higher storage SOC and temperature typically increase fade.
3) Remaining capacity (combined)
Q_remain = (1 − Q_loss_cycle) · (1 − Q_loss_cal)
C_remain(Ah) = C0(Ah) · Q_remain
E_remain(Wh) = C_remain(Ah) · V_nom(V)
This combination avoids double-counting by applying losses sequentially.

How to Use This Calculator

  1. Select your cell chemistry family (or closest match).
  2. Enter initial capacity and nominal voltage for your pack/cell.
  3. Fill in rated cycles to 80% from a datasheet or test data.
  4. Provide your real usage: cycles, DoD, temperature, C-rate, and average SOC.
  5. Enter calendar aging months plus storage SOC and storage temperature.
  6. Click Calculate Aging to see results above the form.
  7. Use CSV or PDF export to save a snapshot for reporting.

Engineering note: For high accuracy, fit parameters using your cell’s measured capacity-vs-cycle data across temperature and DoD ranges.

Cycle aging drivers

Cycle aging mainly comes from charge–discharge work: electrode expansion, micro‑cracking, lithium inventory loss, and impedance rise. The calculator converts your cycle count into effective stressed cycles using depth of discharge, C‑rate, temperature and average state of charge. A Q10 temperature rule approximates faster side reactions as heat increases. Higher DoD and higher C‑rate raise stress multipliers, so the same 500 cycles can behave like far more under aggressive use.

Calendar aging drivers

Calendar aging occurs even without cycling. It is dominated by time‑dependent growth of the solid‑electrolyte interphase and electrolyte oxidation, which are accelerated at storage temperature and high storage SOC. The calculator models this using a square‑root time relationship, scaled by chemistry‑specific coefficients. For planning, compare one year at 25°C and 50% SOC versus one year at 40°C and 90% SOC—the second case shows higher fade.

Interpreting stressed cycles

Effective stressed cycles help translate mixed usage into a single comparable metric. For example, 800 shallow cycles at 50% DoD may produce a similar effect as 400 full cycles, depending on chemistry and temperature. This output is useful when you have partial discharge patterns, regenerative braking, or variable loads. Treat it as a normalization tool rather than a measurement; it aligns scenarios under consistent assumptions.

Design and operations decisions

The results can guide engineering trade‑offs. Lowering average SOC by even 10–15% can reduce SOC‑driven stress, while thermal management that keeps cells near 25°C improves both cycle and calendar life. If fast charging is unavoidable, limiting peak temperature and avoiding high SOC dwell time reduces degradation. Use the safety margin input to produce conservative capacity planning for warranty, range targets, or stationary storage reserve requirements.

Reporting and validation

For credible decisions, calibrate the model against your cell’s test data. Compare predicted remaining capacity to periodic capacity checks and update rated cycles‑to‑80% accordingly. Keep a log of temperatures, C‑rates, and DoD distributions; the export feature supports reporting to stakeholders. Because real aging can be non‑linear and chemistry‑specific, treat outputs as engineering estimates and validate before final design commitments.

FAQs

What does “rated cycles to 80%” mean?

It is the cycle count at which a cell typically reaches 80% of its original capacity under reference conditions. Use datasheet values or your test data for the closest temperature, rate, and depth-of-discharge assumptions.

Why does temperature affect aging so strongly?

Many parasitic reactions accelerate with heat. The calculator uses a Q10-style factor, meaning degradation can roughly double for each 10°C increase, which is a common engineering approximation.

Is remaining capacity simply cycle loss plus calendar loss?

No. The calculator combines them multiplicatively by applying each loss to the remaining capacity. This avoids overstating degradation when both mechanisms act together over the same time period.

How should I choose average SOC values?

Use the time-weighted average SOC during operation and the average SOC during storage. If you have logs, compute the mean over the relevant window. If not, estimate based on your charge limits and dwell time.

What is “effective stressed cycles” used for?

It converts your usage into an equivalent cycle count at reference stress, factoring DoD, C-rate, temperature, SOC stress, and rest. It helps compare scenarios and explains why similar cycle counts can age differently.

Can I rely on the estimate for warranty decisions?

Treat it as a planning estimate. Validate with periodic capacity tests and adjust inputs to match observed behavior. For warranties, apply conservative safety margins and confirm performance across temperature and load extremes.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.