Simplex Firenze C8 25.2V 18Ah Compatible Battery

Simplex Firenze C8 / Milano C7 / Roma-e C8 (2011) — 25.2V Li-ion Replacement Battery

This is a 25.2V 18000mAh (453.6Wh) Li-ion replacement battery for the Simplex Firenze C8 (2011), Milano C7 (2011), Pedelec 8V (2011), and Roma-e C8 (2011) electric bikes. It slots into the same battery bay and connects to the same 25.2V pedal-assist drive system as the original pack. Capacity figures come directly from product data — 18000mAh at 25.2V nominal.

• Firenze C8, Milano C7, and Roma-e C8 compatibility: These three 2011 Simplex models share the same 25.2V battery architecture, connector pinout, and BMS communication protocol — the drive controller on each bike expects the same voltage rail and handshake signal from the pack.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles on a 25.2V e-bike drive system. The BMS correctly reported state-of-charge, engaged cell balancing across the series string, and tripped the low-voltage cutoff at the expected threshold under simulated motor load.
• Post-storage charge protocol for first spring ride: After winter storage, connect the charger and let the pack sit on a slow charge for a full cycle before riding. Cold Li-ion cells carry higher internal resistance — forcing a fast charge below 10°C causes lithium plating on the anode that permanently shaves capacity from the pack.

E-bike motor cutting out mid-hill on a new battery

Sustained climbing draws significantly more current than flat riding — a 25.2V system under heavy motor load can spike well above normal cruise draw. If the BMS detects that current pull exceeding its overcurrent threshold, it trips the output to protect the cell string. This is not a faulty battery; it is the protection circuit working as intended. The BMS resets automatically once the load drops — stop pedalling for a few seconds, then resume at a lower assist level to stay below the trip threshold on steep inclines.

Charger showing no activity after the bike sat unused all season

Li-ion packs that sit discharged for months can drop below the minimum voltage the charger's detection circuit accepts — typically around 20V on a 25.2V system. The charger reads the pack as absent or faulty and refuses to begin a charge cycle. Connect the charger anyway and leave it for 30 minutes without interruption; most chargers will enter a trickle pre-charge mode once the pack voltage nudges above the acceptance threshold. If the charge LED does not change state after 45 minutes, check that resting pack voltage is still above 18V with a multimeter — below that, individual cells may have reversed polarity and the pack cannot be recovered safely.