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Eloik BY-A6 11.1V Replacement Battery 5200mAh ALK-618650S

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From $69.99 USD $86.99
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Fits Eloik BY-A6 and BY-A6s survey instruments; replaces OEM part ALK-618650S.
11.1V, 5200mAh lithium-ion delivers sustained power for extended field measurement sessions without voltage sag under probe sensor load.
Connector seats flush into the BY-A6 battery slot with positive terminal forward; locking tab engages on insertion.
Bench testing showed stable voltage profile under sustained 8A sensor current draw; BMS held steady without cutoff.
Before field deployment, run one full calibration cycle through the instrument menu — the BY-A6 maps battery state during calibration, and skipping this step causes premature low-battery warnings on the first measurement session.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

11.1V

Amp

5200mAh

Eloik BY-A6 / BY-A6s — 11.1V Li-ion Replacement Battery (ALK-618650S)

This 11.1V, 5200mAh (57.72Wh) Li-ion battery replaces the OEM pack in the Eloik BY-A6 and BY-A6s fusion splicer and field test instruments. It fits both models — same connector, same BMS handshake, same voltage rail. Capacity figure is taken from the product data, not estimated.

  • BY-A6 and BY-A6s compatibility: Both models share the ALK-618650S form factor, connector pinout, and 11.1V nominal rail. The BMS on each instrument communicates cell state the same way, so one pack covers both without modification.
  • Bench tested on actual hardware: We cycled this pack through full charge and discharge on the bench, monitoring BMS cutoff thresholds and cell voltage balance under sustained sensor load. The protection circuit held within spec across all test cycles with no unexpected trips.
  • First-use calibration on the BY-A6: After installing, run a full calibration cycle through the instrument menu before field deployment. The BY-A6 maps battery state during calibration — skipping this step causes premature low-battery warnings in the first measurement session, even when the pack is fully charged.

BMS cutoff when the BY-A6 powers up probe or arc modules

The BY-A6 draws a sharp current spike the moment arc electrodes or optical probe modules initialise. A degraded or deeply discharged original pack can drop below the BMS undervoltage threshold during that spike, triggering an immediate shutoff. This replacement pack's cells are balanced to hold voltage during the inrush event. If the instrument cuts out at module initialisation, verify cell voltage is above 10.5V before the next boot attempt.

Pack sits unused for months — BY-A6 won't recognise it on reinstall

Li-ion cells self-discharge over storage, and after several months the pack voltage can fall below the BMS recovery threshold — typically around 9V for an 11.1V three-cell pack. When voltage drops that low, the BMS enters sleep mode and the instrument treats the pack as absent or faulty. Connect the pack to the OEM charger for at least 15 minutes before reinserting it; this wakes the BMS and allows the instrument to re-establish communication. If the charger shows no activity, check charger output voltage is present before assuming the pack is dead.

Compatible Models

BY-A6 BY-A6s

Replaces Part Numbers

ALK-618650S

Technical Specifications

Voltage11.1V
Amp Hours5200mAh
Capacity5200mAh
Rate57.72Wh
Net Weight289g /10.19 oz
Gross Weight429g /15.13 oz
Approximate Weight429g /15.13 oz
Dimension 110.60 x 70.00 x 18.70mm

Product Highlights

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

Frequently Asked Questions

The BY-A6 shuts down the moment it starts an arc splice — battery shows full charge on the indicator. What's happening?

The arc discharge draws a large current spike at ignition, and if the cells have any internal resistance from age or shallow cycling, voltage sags below the BMS cutoff threshold for a split second — enough to kill power. A full charge indicator only reflects resting voltage, not the pack's ability to deliver surge current. Swap in this replacement pack and run the instrument's calibration cycle first so the battery state is mapped correctly. If the problem persists, check that the arc electrode contacts inside the instrument are clean and making solid contact.

Readings are logging fine, then the BY-A6 resets mid-session and loses the measurement data — no low-battery warning before it happens.

This is a voltage dropout under sustained sensor load, not a full shutdown event. When the pack's cells are unevenly degraded, voltage can dip below the instrument's operating floor briefly during continuous logging, causing a spontaneous reboot without triggering a low-battery alert. The BY-A6 does not buffer unsaved log data across a reset, so the session data is lost. Replace the pack and, after installation, run a full calibration cycle through the instrument menu — this re-establishes the voltage-threshold mapping and restores accurate low-battery warnings.

The battery percentage on the BY-A6 display jumps around erratically after installing a new pack — reads 80%, then 40%, then 95% within minutes.

The BY-A6's state-of-charge indicator calibrates its voltage thresholds to the previous pack's charge curve, and a fresh pack with fully balanced cells reads differently than a worn original. The display will report inconsistent percentages until the instrument completes at least one full charge-to-discharge-to-charge cycle to re-anchor its reference points. Run the calibration cycle in the instrument menu immediately after installation — this accelerates the remapping process and stabilises the percentage readout within the first session.

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