25.2V Helkama E2800 Compatible Battery 18000mAh Li-ion

Helkama E2800 / Jopo Electro Series — 25.2V Li-ion 18000mAh Replacement Battery

This is a 25.2V lithium-ion battery pack rated at 18000mAh (453.6Wh), built to replace the original pack in Helkama E2800, E2800A, Jopo Electro, and TE2800 electric bicycles. When the factory pack loses charging capacity and range, this is the direct swap. Voltage, physical dimensions (272.50 × 153.50 × 103.80mm), and connector layout match the original mount point.

• E2800 and Jopo Electro platform fit: These models share the same frame battery bay, 25.2V motor controller voltage rail, and BMS communication protocol. One pack covers all listed variants without adapter modifications.
• Bench tested on actual hardware: We cycled this pack through repeated motor-assist load draws and monitored BMS cutoff thresholds. The protection circuit held stable under sustained climbing current without triggering false low-voltage shutdowns.
• First charge after winter storage: If the bike has been stored unridden through winter, charge at the lowest available rate setting before the first full session. Cold Li-ion cells carry higher internal resistance, and pushing full charge current below 10°C causes lithium plating on the anode that permanently reduces cycle life.

E2800 motor cutting out mid-hill on a new battery

Sustained climbing current on the E2800 motor draws significantly more amps than flat-road pedal assist. If the BMS detects a sustained high-current draw without a corresponding voltage recovery, it trips a protective cutoff to prevent cell damage. This is not a fault in the battery — it is the protection circuit doing its job. After the motor cuts, stop pedalling assist for five seconds to let the BMS reset, then resume at a lower assist level on steep grades.

Charger shows no activity after connecting a stored pack

If a Helkama pack has sat discharged for an extended period, cell voltage can drop below the threshold the charger uses to confirm a valid battery is connected. The charger will show no LED activity or fault-flash instead of a normal charge cycle. Connect the charger and leave it attached for up to 30 minutes — the BMS recovery circuit will slowly pull the cells back above acceptance voltage and the charger will then engage normally. If no response occurs after 45 minutes, check that resting pack voltage reads above 18V with a multimeter before proceeding.