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BK Precision 2650A Replacement Battery 7.4V 5200mAh MB400

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From $51.99 USD $63.99
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Fits BK Precision 2650A, 2652A, 2658A digital multimeters; replaces OEM battery MB400.
7.4V, 5200mAh lithium-ion cell sustains measurement sessions without mid-test shutdown on sustained probe loads.
Slides into the battery compartment with a single locking tab; connector seats flush and latches positively.
We bench-tested this pack under continuous measurement mode with probe initialization cycles; BMS held steady at 7.4V without dropout.
After installing, run the instrument's full calibration sequence in the menu before field use — the multimeter maps battery state during calibration and skipping this step triggers premature low-battery warnings during your first measurement session.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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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.

Delivery and Shipping

🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

Disclaimer

⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

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

Voltage

7.4V

Amp

5200mAh

BK Precision 2650A / 2652A / 2658A — 7.4V Li-ion Replacement Battery (MB400)

This is a 7.4V, 5200mAh Li-ion replacement for the BK Precision MB400 battery pack. It fits the 2650A, 2652A, and 2658A handheld digital multimeters. These meters are used for electrical diagnostics and extended field measurement sessions where battery life directly affects workflow.

  • 2650A / 2652A / 2658A compatibility: All three models share the same battery bay geometry, 7.4V rail, and MB400 connector footprint. The BMS handshake protocol is identical across the series, so one pack covers all three meters without modification.
  • Bench tested on actual hardware: We cycled this pack through the 2650A's probe initialisation sequence, which draws a brief current spike at power-up. The BMS held the voltage rail steady and did not trip into protection mode during repeated cold starts.
  • Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the instrument's menu before field deployment. The 2650A maps battery state during calibration — skipping this step causes premature low-battery warnings during your first measurement session, even with a fully charged pack.

BMS lockout after the 2650A sat unused in a carry case for months

Li-ion cells self-discharge over time. If the pack drops below approximately 2.5V per cell during long storage, the BMS enters a protection state and blocks charging entirely. The meter will show no charge activity and may not power on. To recover the pack, apply a charge at a low rate using a compatible external charger that supports recovery mode — or re-seat the pack in the meter and attempt a charge cycle several times. Most BMS circuits re-initialise once terminal voltage climbs back above 2.8V per cell.

Readings resetting or dropping out mid-logging session

Sustained sensor load during a logging session draws consistent current from the pack. If the cells have capacity fade from shallow cycling, voltage can sag enough mid-session to cause the meter's processor to reset or lose the active log. This is not a firmware fault — it is a voltage dropout event. Fitting a fresh 5200mAh pack restores the voltage headroom the meter needs to sustain continuous measurement without interruption. Check that the pack is fully charged to 8.4V before starting any long logging run.

Compatible Models

2650A 2652A 2658A

Replaces Part Numbers

MB400

Technical Specifications

Voltage7.4V
Amp Hours5200mAh
Capacity5200mAh
Rate38.48Wh
Net Weight205.6g /7.25 oz
Gross Weight355.6g /12.54 oz
Approximate Weight355.6g /12.54 oz
Dimension 140.00 x 39.50 x 21.30mm

Product Highlights

  • Brand: BK Precision
  • Manufacturer: CS
  • Series: Standard
  • Color: Grey
  • Product Type: Li-ion
  • Battery Type: Li-ion
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My BK Precision 2650A powers on fine but shuts off the moment I plug in the USB cable to transfer data — why?

USB data transfer adds a second load on top of the active measurement circuit, and if the pack voltage is already low from a long session, the combined draw pulls voltage below the meter's minimum threshold and triggers a shutdown. This is a load-induced cutoff, not a meter fault. Charge the pack fully to 8.4V before any USB transfer session, and confirm the host PC is not pulling bus power from the meter at the same time.

The 2650A refuses to charge after a new pack install — the charge indicator never lights up.

If the pack sat in transit or storage for an extended period, the cell voltage may have dropped below the BMS recovery threshold, and the meter's internal charger circuit will not engage until minimum voltage is met. Remove the pack, use an external Li-ion charger in recovery or "wake" mode to bring each cell above 2.8V, then re-install and charge normally through the meter. Once the BMS sees voltage above that threshold, the charge indicator will activate within a few minutes.

The battery percentage on the 2650A display jumps around — shows 80% at startup, then drops to 40% after one measurement — is the pack faulty?

The 2650A uses a voltage-threshold method to estimate charge state, not a dedicated fuel gauge IC. A new pack has slightly different voltage curves than the original cells, so the display reads inconsistently until the meter re-calibrates its thresholds over one or two full charge-discharge cycles. Run the pack down to the meter's low-battery warning, then charge fully to 8.4V — repeat this twice and the percentage readout will stabilise to an accurate baseline.

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