18V 4Ah Battery Pack for Professional Cordless E-Screwdriverr
On August 12, 2025, a German power tool maker contacted CMB to develop a higher-capacity battery pack.
It was for its new professional cordless screwdriver platform. The battery needed to deliver steady power during a full 6 to 8 hour work shift. It also had to work in hot outdoor conditions. It needed to meet certification requirements for distribution in the European market.
In addition to extending runtime, the customer required a battery pack that could withstand continuous high-load operation without excessive heat buildup or unexpected BMS shutdowns. The project also had to meet a tight product launch schedule.
Within 6 weeks, CMB designed, tested, and delivered a custom 18V 4Ah lithium-ion battery pack. It met the customer’s performance, safety, and certification needs. This enabled the successful launch of its professional screwdriver series.
Customer Overview
The customer is a Germany-based power tool maker.They are launching a professional cordless screwdriver product line for the European trade market. Its main users include HVAC installers, industrial maintenance technicians, and EV chassis assembly workers.
>They often run tools nonstop during 6–8 hour outdoor or field shifts. The battery pack was a critical component for ensuring uninterrupted productivity while satisfying the compliance requirements of the customer’s European distribution partners.
18V 4Ah Battery Pack Design for Electric Screwdriver
Product Highlights
- Cell configuration: 5S4P (INR18650 20 cells)
- Max continuous discharge rate : 20 C
- Peak / stall current: 80A — 100 ms delay window before BMS trips
- Thermal sensors: Dual NTC — cell core + BMS PCB
- Short-circuit response: <200 µs hard cut
- Thermal derating: −15% output at 50°C (no hard cut until 60°C)
- Cycle life: ≥500 cycles @ 80% DoD
| No. | Item | Specification | Note |
|---|---|---|---|
| 1 | Nominal Voltage | 18V | 3.6V/Cell |
| 2 | Nominal Capacity | 4Ah | @0.2C |
| 3 | Minimum Capacity | ≥3.9Ah | / |
| 4 | Initial Internal Impedance | ≤45mΩ | AC 1KHZ |
| 5 | Standard Charge Voltage | 21V | 4.2V/Cell |
| 6 | Standard Charge Current | 2A | @0.2C |
| 7 | Max Charge Current | 4A | |
| 8 | Standard Discharge Current | 20A | @0.2C |
| 9 | Max. Discharge Current | 80A | / |
| 10 | Discharge Cut-off Voltage | 13.75V | 2.5V/Cell |
| 11 | Cycle Life | ≥500 cycles | Retention: ≥80% |
| 12 | Charge Temperature | 0°C~45°C | Standard Charge |
| 13 | Discharge Temperature | -20°C~60°C | Standard Discharge |
| 14 | Storage Temperature | -20°C~ 45°C | ≤3 Months |
| 0°C ~ 25°C | ≤1 Year | ||
| 15 | Weight | About 560g | / |
18V 4Ah Battery Pack FAQs
Our operators work 6–8 hour outdoor shifts. Will 4Ah be enough without swapping?
For moderate screwdriving load, a 4Ah pack at 18V supports approximately 2–2.5 hours of use before depletion. Most field operations include natural breaks — moving between work stations, setting up, inspecting completed work — which effectively extend usable shift coverage. In practice, most construction and installation clients find 1–2 packs per operator sufficient for a full 8-hour shift.
What certifications are required to sell a cordless screwdriver battery in the EU?
For EU market entry you need: a CE Declaration of Conformity backed by IEC 62133-2 (safety of portable cells and batteries at cell level), UN38.3 (transport safety — required for any air freight), and RoHS 3 (restriction of hazardous substances). CMB provides a full documentation package with each order — including the underlying test reports, not just the declaration — which is what EU distributors and customs authorities increasingly require as standard.
Why does my current 4Ah pack from another supplier keep cutting out in summer?
Most likely cause: single-point thermal sensing. If the thermistor is only on the BMS PCB and not in direct contact with the cell array, the BMS is reading ambient-adjacent temperature, not actual cell temperature. Under high-ambient conditions with sustained 15–20C load, cells can run 10–15°C hotter than the board sensor detects. The pack trips — or worse, doesn’t trip when it should. Dual NTC placement as used in the CMB 4Ah design eliminates this blind spot.
Can we brand the pack with our own label and housing colour?
Yes. CMB operates as a white-label and private-label battery manufacturer. Housing colour, surface finish, label printing, and fuel gauge LED configuration can all be customised.
Tailored Customization
Our design team can create custom battery designs for just about any device or machine.
Timely Delivery
Our efficient production and distribution process gets your product delivered in a timely manner.
Quality Guarantee
We stand by our products and guarantee you’ll be happy with your purchase.
