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Berner BACS 12V Replacement Battery 3000mAh Ni-MH

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From $93.99 USD $115.99
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Fits Berner BACS 12V cordless drills, screwdrivers, and impact drivers with OEM compatibility.
12V Ni-MH chemistry delivers 3000mAh capacity for sustained torque on construction and DIY tasks.
Connector mates the Berner slide-pack slot with positive-negative contact alignment — no locking tab.
Bench testing showed clean voltage ramp on first insertion; BMS accepted full charge cycle without thermal event.
On first use with this Ni-MH pack, run the drill at half load for two cycles before full-torque fastening — allows the pack to establish thermal baseline in the enclosed housing before sustained motor current draw.
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

12V

Amp

3000mAh

Berner BACS 12V — 12V Ni-MH Replacement Battery

This 12V Ni-MH battery replaces the original pack in the Berner BACS 12V cordless power tool range. It carries a 3000mAh (36Wh) capacity and fits cordless drills, screwdrivers, and impact drivers in the BACS 12V platform. Swap it in when the original pack no longer holds charge or when you need a second unit ready on site.

  • BACS 12V platform fit: Berner's BACS 12V tools share a common 12V rail, connector geometry, and pack locking tab across drills, screwdrivers, and impact drivers in that series — one battery form factor covers the range.
  • Bench tested on actual hardware: We cycled this pack through a 12V drill under variable load. The BMS handled motor-start inrush current without nuisance tripping, and cell temperature stayed within safe limits across repeated draw cycles.
  • Break-in load procedure: On first use, run the tool at half load for two cycles before full-torque applications. This lets the BMS profile the motor's inrush current draw before setting its overcurrent protection thresholds — skipping it can cause premature cutoffs during heavy driving tasks.

BMS cutoff on BACS 12V motor-start inrush surge

Every trigger pull on a cordless drill creates a brief current spike — inrush — as the motor armature accelerates from rest. On a 12V Ni-MH pack, this spike can briefly exceed the BMS overcurrent threshold, especially if the pack is cold or the cells have not yet been profiled under load. The BMS reads the spike as a fault and disconnects the output rail. Running the break-in procedure first lets the BMS log that inrush signature and distinguish it from a genuine short-circuit event.

Tool bogs or loses torque mid-task under sustained load

If the BACS 12V drill feels weak or slows under driving pressure, the cause is usually voltage sag — the pack's internal resistance causes the rail voltage to drop under sustained current draw. On Ni-MH cells this worsens as packs age or as contact resistance builds up on the battery terminals. Clean the pack and tool contacts with isopropyl alcohol to remove oxidation. If the no-load terminal voltage reads above 12.5V but the tool still bogs under torque, the cells have degraded and the pack needs replacement.

Compatible Models

BACS 12V

Technical Specifications

Voltage12V
Amp Hours3000mAh
Capacity3000mAh
Rate36Wh
Net Weight675g /23.81 oz
Gross Weight955g /33.69 oz
Approximate Weight955g /33.69 oz
Dimension 108.91 x 53.34 x 113.60mm

Product Highlights

  • Brand: Berner
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Ni-MH
  • Battery Type: Ni-MH
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My BACS 12V drill cuts out the instant I pull the trigger — is the battery faulty?

That's a BMS overcurrent trip, not a dead cell. The motor-start inrush current spike on trigger pull briefly exceeds the BMS protection threshold, and it shuts the output rail down as a safety response. Run the break-in procedure first — two cycles at half load — so the BMS can profile the inrush signature before you apply full torque. If cutouts persist after that, check that the pack terminal voltage sits above 12V at rest before retrying.

The charger never recognises this new pack — no lights, no charge cycle starts.

A Ni-MH pack that has sat in storage can drop below the charger's minimum acceptance voltage. Some Berner chargers will not initiate a charge cycle on a pack they read as outside the expected voltage window. Try a brief trickle or "boost" charge if your charger has that mode — it nudges the cell voltage up to the threshold where the main charge cycle triggers. If no boost mode is available, check the pack terminal voltage with a multimeter; anything below about 9V on a 12V Ni-MH pack will need a compatible recovery charger before normal charging resumes.

The drill runs fine on a fresh charge but capacity drops off noticeably after a few weeks of light use.

That pattern is shallow-cycle degradation — common in Ni-MH chemistry when packs are topped up frequently without being fully discharged first. Partial cycles prevent the cells from fully equalising, and capacity fades faster than it would under full discharge-and-recharge cycles. Run the pack down until the tool noticeably slows, then charge it fully — do this two to three times in a row to partially restore cell balance. Going forward, avoid putting the pack on charge after only short bursts of use.

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