Store Makita BL 18V packs at ~30–50% SOC (target ~40%), in cool (15–25°C), dry (<60% RH), ventilated storage. Label and FIFO-rotate packs, use non-conductive trays, and log temp/humidity. Do monthly visual + OCV spot checks and top up every 2–3 months. Quarantine any swollen/hot/smelling packs; use OEM charger for wake-ups and only perform current-limited lab wakes for deeply discharged units. Immediate: set spares to ~40% SOC, place a temp/RH logger, and start monthly OCV checks.

Storing Makita 18V BL-series packs at ~30–50% SOC in cool (15–25 °C), dry, well-ventilated conditions with routine visual and OCV checks plus a clear quarantine policy substantially reduces swelling, BMS lockouts, and premature capacity loss. This guide gives the exact SOC/temperature targets, handling and packing practices, inspection cadence, wake-up/charging rules, and warehouse-scale controls you can apply today to preserve life and reduce safety incidents.

Safety first

Immediately quarantine any pack that is swollen, hot, emitting odor, leaking, or smoking. Don’t charge, puncture, or compress it; move it to a non-combustible outdoor area and follow hazardous-waste/disposal rules.
Store packs in a cool, dry, well-ventilated area away from flammable materials and ignition sources. Use insulated trays or metal cabinets with ventilation for bulk storage.
Follow ESD precautions when handling PCBA/BMS exposed terminals; use PPE when checking suspect packs. Never store packs in direct sunlight, near heaters, or in vehicles left in hot conditions.

What you’ll need

Simple voltage meter / multimeter for spot OCV checks.
IR thermometer (optional) for surface-temp checks.
Humidity/temperature logger for storage room (recommended for fleet/warehouse).
Non-conductive separators or trays and anti-static packaging for individual packs.
Visible labeling supplies (date-in, SOC, lot/serial).

Recommended storage state-of-charge (SOC) & why

Store at ~30–50% SOC as a general rule. This range balances minimizing SEI growth (slows calendar fade) and avoiding deep-discharge BMS latches. For long storage (>6 months), target ~40% SOC.
Do not store at 100% (increases long-term chemical stress) and avoid leaving packs at 0% (risk BMS latch and irreversible cell damage).

Temperature & humidity — practical ranges

Ideal ambient: 15–25 °C. Cooler is better for calendar life but avoid freezing.
Acceptable short-term: 5–30 °C for temporary storage; avoid temperatures above 40 °C.
Relative humidity: keep <60% RH where possible; high humidity increases corrosion risk on contacts and terminals. Use desiccants or climate control for long-term indoor storage.

Physical storage & packing practices

Store packs seated upright or in manufacturer trays to prevent terminal contact and to minimize mechanical stress. Use non-conductive separators to avoid accidental shorting.
Keep terminals clean, dry and protected — do not stack packs so contacts touch metal. Cover or cap exposed terminals when possible.
Label each pack with date in, nominal SOC at receipt, lot/serial — rotate stock FIFO (first in, first out). For fleet spares, record last-use date and cumulative cycles if available.

Long-term storage intervals & periodic checks

Short term (<3 months): store at ~30–50% SOC, check monthly for visual issues.
Medium term (3–12 months): check every 2–3 months: visual inspection, OCV spot check, and top-up to target SOC if drifted significantly.
Long term (>12 months): recondition: measure OCV, attempt a controlled charger-wake (OEM charger) and perform a low-rate capacity check on samples; retire packs showing large DCIR rise or capacity < ~70–80% of rated (policy-dependent).
Maintain a simple log: date, pack ID, OCV, visible condition, any action taken.

Charging & wake-up rules before storage and after storage

Before storage: set stored SOC to ~40% using the OEM charger and allow the pack to rest (30–60 min) before shelving.
After long storage or if OCV is low: use the OEM charger first; if charger refuses, perform a current-limited bench wake only in a controlled lab (start ≤ C/20) — stop if pack heats or smells. Do not bypass BMS.
Avoid charging in very cold (<5 °C) or very hot (>40 °C) environments; warm or cool pack to recommended range before charging.

Handling degraded or suspect packs

If OCV is extremely low (<~10–12 V pack-level for many 18V packs) or the pack gets hot during small wake current, quarantine and escalate to qualified lab/RMA.
For packs with physical damage (cracks, crushed housing, leaking), do not attempt to charge; follow hazardous battery disposal procedures.
Keep suspect packs separate and mark QUARANTINE with date and observed symptom.

Warehouse tips for scale / fleet operations

Use climate-controlled storage rooms or cabinets for spares; a single temp/humidity logger in each room is often sufficient to spot excursions.
Implement a simple labeling system: Received date / Stored SOC / Next check date. Rotate stock and avoid single-pack “always hot” rotation.
Train receiving staff to perform a visual & OCV quick check on incoming returned packs and log results.

Simple inspections & quick tests before return to service

Visual: housing, label, terminals, no swelling, no leaks.
OCV: measure after 30 min rest. Expect ~20.0–21.6 V full; <17–18 V is a red flag for many 18V packs.
Tool swap test: if safe, put the pack in a known-good tool and observe immediate behavior; does the tool cut out quickly?
If suspect: run a controlled low-rate capacity spot test or send to lab. Do not disassemble packs in your general warehouse.

Fire safety & emergency planning

Store batteries away from general commodities; prefer metal cabinets or segregated areas with clear signage and fire extinguisher (Class D or appropriate battery fire suppression where required).
Have a documented emergency response: evacuation, quarantine procedure, who to call for battery disposal and whether local fire services must be notified.
Train staff on immediate steps for a thermal event: move people away, remove nearby combustibles, and only trained responders should approach a smoking/swollen pack.

Quick checklist

Set stored SOC to ~30–50% before shelving.
Keep ambient 15–25 °C and RH <60%; log temp/humidity.
Label packs with date-in and target check date; rotate FIFO.
Monthly visual/OCV checks for short/medium storage; every 2–3 months for medium term.
Quarantine & isolate any pack showing swelling, heat, leak, or strange odor.

Frequently Asked Questions

Q — Can I store Makita 18V packs fully charged for months?
A — Storing at 100% increases calendar aging; prefer ~30–50% SOC for months-long storage.

Q — How often should I top up stored packs?
A — Check every 2–3 months for medium-term storage; top up to target SOC if OCV drifted significantly.

Q — Is it safe to store packs in a metal cabinet?
A — Yes, if the cabinet is ventilated and terminals can’t short to metal. Avoid stacking packs with exposed contacts touching metal.

Q — What temperature is worst for battery shelf life?
A — High temperatures accelerate capacity loss; sustained temps above ~40 °C are particularly harmful.

Q — My pack shows “full” but drains fast after storage — why?
A — BMS miscalibration, elevated DCIR from aging, or cell imbalance can cause that. Run a controlled capacity/OCV test and consider lab evaluation.

Conclusion — one-line takeaway + 3 immediate actions

Store Makita 18V packs at moderate SOC (~30–50%), in cool, dry, ventilated conditions, with routine visual & OCV checks and clear quarantine rules for suspect units; these simple controls preserve life and reduce safety incidents.

Immediate actions:

Bring stored packs to ~40% SOC now and label with date-in.
Place a temp/humidity logger in your battery storage area and review the last 30 days.
Add a monthly visual + OCV spot-check to your receiving/returns workflow.

Safe Storage Practices for Makita 18V Lithium-Ion Batteries