About this replacement
Eloik BY-A6 / BY-A6s — 11.1V Li-ion Replacement Battery (ALK-618650S)
This 11.1V 7800mAh Li-ion pack replaces the ALK-618650S battery in the Eloik BY-A6 and BY-A6s fusion splicers. It fits the original battery bay with no modification. Voltage and cell count match the factory specification exactly.
- BY-A6 and BY-A6s compatibility: Both models use the same 11.1V three-cell architecture, the same ALK-618650S connector pinout, and the same BMS handshake protocol. One pack covers both variants without any wiring or adapter changes.
- Bench tested on actual hardware: We ran this pack through a full charge-discharge cycle on a BY-A6 unit. The BMS communicated correctly at every charge state, and the protection circuit responded to the motor-drive current spike during arc calibration without tripping.
- Post-install calibration on the BY-A6: After fitting this pack, run a full calibration cycle through the BY-A6 instrument menu before going into the field. The splicer maps battery state during that sequence — skipping it causes the battery indicator to show premature low-power warnings during your first splicing session.
Why the BY-A6 shuts down during arc discharge or motor drive
The BY-A6 draws a sharp current spike when it fires the electrode arc or drives the fibre alignment motors. An aged or degraded cell pack has elevated internal resistance, which causes the pack voltage to sag below the BMS cutoff threshold during that spike — triggering an immediate shutdown. The fault disappears between splices because the voltage recovers under low load. A fresh pack with low internal resistance holds voltage through the spike and keeps the instrument running.
BY-A6 not recognising a new pack after storage
If the replacement pack sat in a warehouse for several months, its resting voltage may have dropped below the BMS re-initialisation threshold. The splicer powers on briefly and then cuts out, or shows a battery error immediately. Place the pack in the BY-A6 charger and leave it for at least 30 minutes before attempting to boot the instrument — the charger applies a low-current recovery charge that wakes the BMS. Once the pack registers above 10.5V, normal charging and communication resume.