#6 · Using a Battery Pack Safely: What Matters Most?

#6 · Using a Battery Pack Safely: What Matters Most?

The short answer
  1. The protection circuit (BMS) inside a battery pack is a safety device that guards against overcharge, over-discharge and overcurrent. Even so, good habits are needed so that risks such as outside heat, wrong wiring or a charger that does not match the specification are avoided before the BMS ever has to cut off.
  2. Series connection is never allowed; charge with the dedicated charger and store packs with some charge left.
  3. If swelling, leakage, an unusual smell or smoke appears, stop using the pack; if there is heat, gas or smoke, do not touch the pack, evacuate and call the fire service (119 in Korea).

Articles #1 to #5 covered how to read a spec sheet and choose a battery pack. This article covers how to use the chosen pack safely. The rules below are a few essentials drawn from the safe-use guide and safety guide that POWERCRAFT provides to customers.

1. Charging — use the dedicated charger and disconnect when full

  • Use the dedicated charger. Lithium batteries must be charged in constant-current, constant-voltage (CC-CV) mode. For safe use, choose a charger that matches the battery's charge voltage and charge current specification.
  • Always check the charge current on the spec sheet. Accepted charge current differs between standard packs, power packs and custom-built packs (article #5).
  • Disconnect when fully charged. Do not leave or store a pack with the charger still connected.
  • Charge before first use. For safety, most battery packs leave the factory at 20–40% charge.

2. Connection — no series wiring, and generous cable ratings

  • Do not connect packs in series. The protection circuit inside each pack is designed for that pack's voltage. Connecting two packs in series puts a higher voltage on the circuit than the design allows, and the protection may not work properly. If a higher voltage is needed, a new pack of that voltage must be ordered (see article #1).
  • Do not mix new and used packs. Parallel connection is possible only to a limited extent, between new packs of the same specification.
  • Rate cables and terminals for the voltage and current. When wiring, choose cables and terminals based on the maximum voltage and maximum current the battery can deliver (a 1.5× margin over the specification is recommended). How to read current is covered in article #4.
  • Check wiring and connections before switching on. Installation and wiring should be done by a qualified electrician, with regular checks afterwards.

3. Temperature and environment — avoid high heat and impact

  • Charge and discharge within 0–45°C. The best range for performance and service life is 15–30°C.
  • Places to avoid. Direct sunlight, enclosed spaces where heat builds up, places where water can reach the pack, and places with repeated vibration or shock.
  • For use in special conditions such as high or low temperature, high humidity or vibration, please consider a custom build designed for that environment.

4. Storage — disconnect and leave some charge

  • Store with the charger and the machine disconnected; for long-term storage, 30–50% charge is recommended.
  • Check the voltage and top up every 3 months. The protection circuit draws a small amount of power even in storage. A pack left below 5% can reach over-discharge within 1–2 weeks, and a pack damaged by over-discharge may not be rechargeable.
  • A battery pack is a consumable. Ageing progresses over time even with little use. Check older packs regularly for their condition and runtime, and consider replacement if performance has clearly dropped.

5. Warning signs — stop when seen, evacuate when serious

  • Swelling, leakage, cracks or signs of impact — stop using and charging, and contact the manufacturer.
  • Rising temperature, an unusual smell, hissing or gas — do not touch or move the battery; warn others, evacuate and call the fire service.
  • Smoke or flames — evacuate the whole area and do not go back in. When calling, say first that a lithium-ion battery is involved.

A lithium battery fire behaves differently from an ordinary fire and can reignite after the flames go out. The rule is to evacuate first rather than trying to put out the fire or move the battery alone.

In short
  1. Charging. Charge with a dedicated charger that matches the specification, and disconnect when full.
  2. Connection. No series wiring, and cables and terminals rated with a 1.5× margin or more.
  3. Storage. Disconnect the charger and the machine, keep 30–50% charge for long-term storage, and check every 3 months.
  4. Warning signs. Swelling or leakage means stop using; heat, gas or smoke means do not touch, evacuate and call the fire service.
Order from the official shopSafety guide (.pdf)

— charging conditions and operating temperatures for all 49 standard packs are listed on each product's spec sheet. If the pack must be used in special conditions such as high or low temperature, high humidity or vibration, browse the POWERCRAFT custom build projects and fill in the specification request. POWERCRAFT will quote to suit the operating environment.

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