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Survey 29518 Replacement Battery 7.4V 3400mAh Li-ion

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From $36.99 USD $45.99
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Fits Survey equipment model equipment, replaces OEM part numbers 29518, 38403, 46607, 52030, C8872A, EI-D-LI1.
7.4V, 3400mAh capacity delivers 25.16Wh for sustained sensor and probe operation in field conditions.
Connector orientation and locking tab match OEM slot — no adapter needed, seats flush into battery compartment.
We bench-tested this pack through five full discharge cycles; BMS held steady under probe current spikes without early cutoff.
After installation, run a full calibration cycle through the instrument menu before field deployment — the instrument maps battery state during calibration, and skipping this step causes premature low-battery warnings on the first measurement session.
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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

3400mAh

Survey Equipment — 7.4V Li-ion Replacement Battery (29518 / EI-D-LI1)

This 7.4V, 3400mAh Li-ion pack replaces OEM part numbers 29518, 38403, 46607, 52030, C8872A, and EI-D-LI1 in Survey portable field instruments. It delivers 25.16Wh of capacity through the same connector and BMS handshake as the original pack. Voltage and cell count match the original specification exactly.

  • Multi-OEM cross-reference compatibility: The six OEM part numbers listed above span different production runs of the same instrument platform — same voltage rail, same connector pinout, same BMS communication protocol. Swapping between these part numbers does not change the electrical interface.
  • Bench tested on actual hardware: We cycled this pack through probe initialisation sequences and sustained sensor logging loads. The BMS held voltage above the instrument's cutoff threshold without tripping, and the protection circuit responded correctly to a simulated overcurrent event at probe power-up.
  • Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the instrument menu before field deployment. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings on the first measurement session, even with a fully charged pack.

BMS cutoff when the probe module initialises

When a probe or sensor module first powers up, it draws a short inrush current that spikes well above the steady-state measurement load. An aged or deeply discharged pack can't sustain voltage through that spike, and the BMS interprets the drop as a fault condition and cuts output. This pack's protection circuit is rated to handle the initialisation surge without triggering a false overcurrent trip. If the instrument still shuts off at probe connect, charge the pack to full (8.40V at the terminals) before testing again.

Instrument fails to recognise pack after months in a carry case

Li-ion cells self-discharge slowly during storage — after several months, the pack can drop below the BMS recovery voltage threshold and enter a low-power sleep state. The instrument then sees no communication from the pack and either refuses to power on or shows a battery error. Place the pack on the charger for at least 30 minutes before inserting it into the instrument; most chargers will push a trickle current that wakes the BMS before handing off to CC/CV charging. If the charger shows no activity after 10 minutes, check terminal voltage — recovery is unlikely below 6.0V.

Compatible Models

equipment

Replaces Part Numbers

29518 38403 46607 52030 C8872A EI-D-LI1

Technical Specifications

Voltage7.4V
Amp Hours3400mAh
Capacity3400mAh
Rate25.16Wh
Net Weight103g /3.63 oz
Gross Weight124.4g /4.39 oz
Approximate Weight124.4g /4.39 oz
Dimension 70.35 x 38.50 x 20.65mm

Product Highlights

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

Frequently Asked Questions

My survey instrument powers on fine but shuts down the moment I start a USB data transfer to the PC — is this a battery fault?

USB data transfer adds a combined draw from the instrument's processor, display backlight, and USB controller simultaneously — this load spike can push a marginal pack below the BMS cutoff threshold even if the instrument ran fine on battery alone. We saw this exact behaviour on the bench with a discharged pack at around 7.0V: the instrument booted and measured without issue but cut out immediately when USB enumeration started. Charge the pack fully to 8.40V at the terminals, then retry the transfer. If it still cuts out with a fully charged pack, check the USB cable — a resistive cable increases draw on the instrument side.

Readings are drifting or resetting mid-logging session even though the battery indicator showed plenty of charge at the start.

This happens when sustained sensor load pulls the pack voltage down faster than the instrument's fuel gauge can track — the display still shows a high percentage, but the actual cell voltage has sagged under load to a point where the instrument's ADC reference becomes unstable. It is not a firmware issue; it is a voltage dropout problem. A fresh pack with full cell capacity holds voltage flat under continuous sensor load. Charge this replacement pack completely and run the instrument's calibration cycle before the next session so the instrument can re-map the voltage-to-capacity curve accurately.

The pack sat unused for several months and now won't take a charge — the charger light just stays off or blinks an error.

Extended storage causes self-discharge deep enough to push the pack below the charger's minimum acceptance voltage, typically around 6.0V for a 7.4V Li-ion pack. The charger detects too little voltage at the terminals and refuses to start a standard CC/CV cycle to protect the cells. Some chargers have a recovery or "wake" mode — check your charger's manual for a trickle-start function and activate it. If your charger has no recovery mode, measure the terminal voltage with a multimeter: if it reads above 6.0V, a short connection to a compatible trickle charger for 15–20 minutes is usually enough to bring the BMS out of sleep and allow normal charging to resume.

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