Mitutoyo 12BAA240 Surftest SJ-201 Replacement Battery 6V 700mAh
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Mitutoyo 12BAA240 Surftest SJ-201 Replacement Battery 6V 700mAh - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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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Delivery and Shipping
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Disclaimer
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Mitutoyo 12BAA240 Surftest SJ-201 Replacement Battery 6V 700mAh - is backordered and will ship as soon as it is back in stock.
Voltage
6V
Amp
700mAh
Mitutoyo Surftest SJ-201 — 6V Ni-MH Replacement Battery (12BAA240)
This is a 6V, 700mAh Ni-MH replacement battery for the Mitutoyo Surftest SJ-201 portable surface roughness tester. It slots directly into the SJ-201 battery compartment and powers the instrument during surface finish measurements on the shop floor or in the lab. Voltage and cell count match the original 12BAA240 / 5HR-AAAU specification.
- SJ-201 compatibility: The SJ-201 runs a fixed 6V rail with five Ni-MH cells in series. This pack replicates that cell count and connector orientation, so the BMS handshake completes on first boot without triggering a voltage mismatch warning.
- Bench tested on actual hardware: We cycled this pack through the SJ-201's probe initialisation sequence, which briefly draws above the steady-state load. The BMS held without tripping on cold-start current spikes across multiple back-to-back measurement sessions.
- Calibration cycle before field deployment: After installing a fresh pack, run a full calibration cycle through the SJ-201 instrument menu before taking it into production. The instrument maps battery state during calibration — skipping this causes premature low-battery warnings to appear during the first measurement session.
SJ-201 shutting down mid-measurement after sitting unused for months
Ni-MH cells self-discharge at roughly 1–3% per day at room temperature. A pack left in the instrument for two or three months in a carry case can drop below the SJ-201's BMS recovery threshold — around 4.5V for this five-cell pack. When the charger is reconnected, the BMS may not recognise the depleted pack and will refuse to charge it. Reconnect the charger and hold the connection for at least 15–20 minutes to allow the BMS to wake from sleep mode before the charge cycle starts.
SJ-201 readings drifting or resetting mid-logging session
The SJ-201 drives the stylus drive motor and processes sensor signals simultaneously during a logging run. This sustained combined load pulls the pack voltage lower than during a single spot measurement. An ageing cell with elevated internal resistance causes a voltage dropout that the instrument interprets as a reset event, corrupting the in-progress log. If readings drop out consistently on longer traversals, check open-circuit voltage — a healthy pack should read above 6.0V at rest. A pack reading below 5.7V at rest under no load needs replacement.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Mitutoyo
- Manufacturer: CS
- Series: Standard
- Color: Green
- Product Type: Ni-MH
- Battery Type: Ni-MH
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
The SJ-201 powers on fine but shuts off the moment the stylus starts its traverse — why?
The stylus drive motor draws a short current spike at the start of each traverse stroke. If the pack voltage sags under that spike — common with a partially depleted or aged Ni-MH pack — the instrument's under-voltage protection trips before the measurement completes. We saw this on the bench with cells below about 5.5V under load. Charge the pack fully, then check that open-circuit voltage reads above 6.0V before running another traverse.
I left a new pack on the shelf for a few months and now the SJ-201 charger light won't come on — is the battery dead?
Ni-MH packs that have self-discharged below roughly 4.5V total can appear dead to the charger because the BMS sits in a low-power sleep state and does not respond to a normal charge handshake. Connect the charger and leave it connected for 20 minutes without interruption — this allows a trickle voltage to raise the pack above the BMS wake threshold. Once the charge indicator activates, let the pack complete a full charge before using the instrument.
The SJ-201 shuts down every time I transfer measurement data to a PC via USB — the battery reads fine before I plug in the cable.
USB data transfer adds a second load path on top of the instrument's active measurement circuits, and the combined draw can push the pack below the SJ-201's operating voltage floor even if the battery indicator looks acceptable before the transfer starts. This happens most often when the pack is at 60–70% state of charge. Charge the pack to full before any USB session, and confirm open-circuit voltage is above 6.0V before connecting the cable.
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