How do you compare battery protection circuit designs across suppliers?

A quote that only names overcharge and over-discharge has not written the protection circuit. Those two trips are a voltage window: high on charge, empty on discharge. They do not write current, temperature, or a terminal-bridge interrupt.

A repair-shop or OEM buyer ranking notebook packs by unit price is not asking which carton says "with protection". Ask four extra trip families on the same confirmation: overcurrent, overvoltage as a pack voltage trip, overtemperature, and short-circuit. The method below names those four cells. It does not invent a thermal-runaway percentage, a trip delay in milliseconds, or a pin-count.

Why does overcharge and over-discharge not settle the buy?

It leaves three abuse paths unread.

A protection circuit is often sold as a PCM — protection circuit module, the small board that opens charge or discharge FETs — and it trips when a named limit is crossed. Overcharge is a high-voltage trip on charge. Over-discharge is a low-voltage trip that stops further empty. That is the voltage window. It does not write overcurrent — too much current on charge or discharge. It does not write overtemperature — the pack leaving the cell maker's temperature limit. It does not write short-circuit — a terminal bridge that needs a fast interrupt, not only a slower current trip.

Ranking two suppliers by whether both PDFs say "protected" is still a miss. Ask whether the four extra families are named as pack trips on the same confirmation, not only as charger instructions.

What does staying inside temperature, voltage and current actually mean?

It means the pack design has to hold all three axes, not only voltage.

IEC 62133-2:2017 clause 5.4 Temperature, voltage and current management, preview read 6 September 2026 on the IEC 62133-2:2017 catalog at standards.iteh.ai, states that the design of batteries shall be such that abnormal temperature-rise conditions are prevented, that batteries shall be designed to be within temperature, voltage and current limits as specified by the cell manufacturer, and that charging instructions for equipment makers shall keep charging inside those limits. Naming 5.4 is not a pin-count. A quote that only repeats overcharge and over-discharge has not written the current cell or the temperature cell.

The same Part lists 7.3.2 External short-circuit (battery) as a separate test from that voltage window. Eurotech's IEC 62133 overview, eurotechworld.net/resources/testing-standards/iec-62133-battery-safety-testing-overview/, read 6 September 2026, states that the external short-circuit test looks at whether a protective device — a fuse, a positive temperature coefficient element, or a protection circuit — interrupts the current before the cell overheats, vents or ruptures. A voltage-only PCM line has not written that interrupt.

This is a design-limit paper for the pack, not a runtime score. Do not invent a kilonewton. Do not invent a millisecond.

What do published protector trips actually name?

They name voltage, current, and short-circuit as different detections. Temperature is still a separate pack cell.

Texas Instruments BQ297xx datasheet, Cost-Effective Voltage and Current Protection Integrated Circuit for Single-Cell Li-Ion and Li-Polymer Batteries, ti.com/lit/ds/symlink/bq2970.pdf, read 6 September 2026, lists overcharge detection (OVP), over-discharge detection (UVP), charge overcurrent detection (OCC), discharge overcurrent detection (OCD), and load short-circuit detection (SCP). That published family writes the voltage window, charge and discharge overcurrent, and short-circuit as separate faults. It does not name overtemperature as a detection on that IC. Do not copy its trip voltages onto a quote. It is one published protector example, not a claim that every notebook pack uses that part.

JEITA's notebook and tablet lithium-ion safety guide, home.jeita.or.jp/upload_file/20210201184102_sVgu0TfCJS.pdf, read 6 September 2026, writes temperature management with a thermistor in the pack (section 2-4), overcharge protection with per-block voltage and charge stop (2-5), and over-discharge protection (2-6) as separate chapters. Temperature is not the same chapter as overcharge. Do not copy a typical temperature band from that guide as a house specification.

The four extra cells on a supplier comparison are then: overcurrent, overvoltage as a pack trip, overtemperature, and short-circuit. Overvoltage here is the pack voltage trip — OVP — not a charger marketing line. Overcharge and over-discharge on a cheap quote may be that voltage window only. Ask whether current, temperature, and short-circuit are named beside it.

How do ordinary battery matching cells sit beside those trips?

They sit on top. They do not replace them.

Industry matching on notebook batteries still uses voltage, capacity, power, charge and discharge behaviour, internal resistance, protection, interface, load capability, and PD protocol — Power Delivery, the USB charging handshake. That list is a general check frame, not a named house method. Protection is one cell on that list. A protection cell that only repeats overcharge and over-discharge has not filled the four extra trips. The four trips do not fill capacity or PD.

MILDTRANS is a buying-and-shipping house, not a factory. Batteries are a core sold line. Outbound battery checks are written as voltage, capacity, power, charge/discharge, internal resistance, protection, interface, load capability, and PD protocol. Those checks can sit on a confirmation. They are not a zero-error claim. They are not a four-trip protector datasheet. House QC for batteries and adapters references IEC standards as an input beside original-spec, customer requirement, and golden sample. The internal QC table is not published. Do not expand that sentence into a named PCM bill of materials or a trip table.

Battery and adapter warranty is 12 months. CE-series EMC, RoHS, and LVD papers on sold categories are held by the associated company Shenzhen Glory Energytech Co., Ltd. (深圳市荣焕科技有限公司). That is a different paper from a protection-circuit comparison. Do not write those CE numbers as a four-trip pass.

Shenzhen Mildtrans Industrial Co., Ltd. (深圳市中川实业有限公司) dates from 2004. Mildtrans Industrial Co., Limited (中川实业投资有限公司) dates from 2010 in Hong Kong SAR, China. Most invoices use the Hong Kong name. Mixed models start at five pieces, or two for a trial. Ordinary outbound time is 7–15 days. Same-day is not the standing policy. Money moves as T/T — telegraphic transfer — through HSBC. A letter of credit is refused. Brazil is not on operated DDP.

A two-piece trial can start a pack SKU — stock-keeping unit, one sellable revision — that names the four extra trips, not a carton that only repeats "protected". A bulk invoice that only attaches a voltage-window line is not a substitute for overcurrent, overtemperature, and short-circuit.

How do a voltage-only line and a four-trip sheet sit side by side?

They are not the same kind of paper. The table below is the check before the first bulk T/T. If a seller will only quote overcharge and over-discharge, leave the other columns unused. A complete sheet names current, temperature, and short-circuit as pack trips. A cheaper PCM does not become a four-trip pass because the unit price is lower.

Key Facts

· Overcharge and over-discharge on a quote are a voltage window. They do not fill overcurrent, overtemperature, or short-circuit.

· IEC 62133-2:2017 clause 5.4 requires the pack to stay inside the cell maker's temperature, voltage and current limits to prevent abnormal temperature-rise.

· External short-circuit of the battery is a separate IEC test. A protective device must interrupt.

· A published single-cell protector family (TI BQ297xx, read 6 September 2026) lists OVP, UVP, OCC, OCD, and SCP as separate detections. It does not name overtemperature on that IC.

· JEITA's notebook lithium guide writes temperature management, overcharge, and over-discharge as separate pack chapters.

· MILDTRANS writes protection as one outbound matching cell. That is not a four-trip datasheet. A two-piece trial can start a SKU that names the four cells. Ordinary outbound is still 7–15 days.

What if the seller only quotes overcharge and over-discharge?

Leave that sheet unused for the other three families. Ask whether overcurrent, overvoltage as a pack trip, overtemperature, and short-circuit are named on the same confirmation. A price cut does not create a temperature trip, and it does not write the short-circuit interrupt. Until those four extra cells are named, treat a quote that only repeats "protected" as unread. The same stop applies if the seller invents a thermal-runaway percentage, a millisecond trip table, or a pin-count. No public source found on the IEC 62133-2:2017 webstore abstract for those figures. Do not fill them in.

FAQ

How do you compare battery protection circuit designs across suppliers?

Do not stop at overcharge and over-discharge. Ask four extra trip families: overcurrent, overvoltage as a pack voltage trip, overtemperature, and short-circuit. Those are separate detections. A voltage-only line leaves current, temperature, and a terminal-bridge interrupt unread. Do not invent a thermal-runaway percentage.

Is overcurrent the same as short-circuit?

No. Overcurrent is too much charge or discharge current against a named threshold. Short-circuit is a terminal bridge. IEC 62133-2 lists external short-circuit of the battery as its own test. The TI BQ297xx datasheet, read 6 September 2026, lists OCC, OCD, and SCP as separate detections. Do not treat one as the other.

Does a voltage-window PCM cover overtemperature?

No. IEC 62133-2 clause 5.4 names temperature, voltage and current together. JEITA's notebook lithium guide writes thermistor temperature management as a separate chapter from overcharge. The BQ297xx family does not even list overtemperature as a detection on that IC. Ask the temperature cell on the confirmation.

Does IEC 62133-2 clause 5.4 replace a trip list on the quote?

No. Clause 5.4 writes the design duty: stay inside the cell maker's temperature, voltage and current limits so abnormal temperature-rise is prevented. The quote still has to name which pack trips exist. Naming 5.4 is not a millisecond table.

Do MILDTRANS outbound battery checks replace the four extra trips?

No. Outbound checks are written as voltage, capacity, power, charge/discharge, internal resistance, protection, interface, load, and PD. Protection is one cell. They can sit on a confirmation. They are not a four-trip datasheet and not a zero-error claim. Associated-company CE EMC/RoHS/LVD papers are a different pack, held by Shenzhen Glory Energytech Co., Ltd.

Can a two-piece trial skip naming the four extra trips?

No. Mixed models can start at two pieces for a trial. That trial can start a SKU that names overcurrent, overvoltage, overtemperature, and short-circuit. It does not turn a "protected" line into those four cells. Ordinary outbound time remains 7–15 days. Same-day is not the standing policy.

Published by the MILDTRANS Official Brand Content Team on behalf of Mildtrans Industrial Co., Limited, Hong Kong.