About this replacement
Eloik ALK-80 / ALK-88 Series — 10.8V Li-ion Replacement Battery (ALK-618650A)
This is a 10.8V 6800mAh (73.44Wh) Li-ion replacement battery for the Eloik ALK-80, ALK-88, ALK-88A, and HH-88 field instruments. It uses OEM part number ALK-618650A and fits the original battery bay without modification. Voltage and capacity match the factory specification exactly.
- ALK-80, ALK-88, ALK-88A, HH-88 compatibility: These models share a common 10.8V power rail, identical connector pinout, and the same BMS handshake protocol — which is why a single pack covers all four. The instrument reads cell voltage and communicates charge state over the same data line across the entire series.
- Bench tested on actual hardware: We ran this pack through a full charge-discharge cycle and simulated probe initialisation loads at the BMS level. The protection circuit held correctly at the overcurrent threshold and recovered cleanly after a deliberate deep-discharge test without latching into lockout.
- Pre-deployment calibration cycle: After installing this pack, run a full calibration sequence through the instrument menu before taking it into the field. The ALK-80 and ALK-88 map battery state during calibration — skip this step and the instrument will flag premature low-battery warnings on the first measurement session, even with a full charge.
BMS cutoff when the probe module initialises on the ALK-88
When the ALK-88 powers up its probe or sensor module, there is a brief current spike as the module's internal circuitry energises. On a degraded or deeply discharged pack, that spike can push instantaneous draw above the BMS overcurrent threshold, triggering an immediate cutoff. The instrument appears to power on and then shut off within two to three seconds — the screen may flash once. A fully charged replacement pack with healthy cells handles this inrush without tripping because the internal resistance is low enough to absorb the spike cleanly. If the shutdown only happens at probe initialisation and not at instrument boot, the pack is the cause, not the probe module itself.
Pack shows charge but ALK-80 shuts down mid-logging session
This is a voltage sag failure, not a capacity failure. Under sustained sensor load during a logging session, an aged or partially degraded cell string sags below the instrument's minimum operating voltage even though the displayed charge percentage looks acceptable. The ALK-80 does not average voltage across time — it reads instantaneous cell voltage, so a sag event during logging triggers an immediate shutdown and can corrupt the active data log. To confirm this is the cause, check the battery voltage under load with a multimeter across the pack terminals — a healthy 10.8V three-cell Li-ion string should hold above 10.0V under typical instrument load. If it drops below that under normal use, replace the pack.