New Lithium Battery: Fusion Returns to Flashing Red After Reaching Full
On the very first charge of a brand-new lithium (LiFePO4) battery, a Fusion bank may reach solid green, then return to flashing red at a low current, and repeat that loop for several hours before settling on solid green for good. This is normal: the battery's BMS is top-balancing its cells for the first time, and the charger is responding correctly to the small voltage shifts the BMS creates during this process.
What's Happening
A new lithium battery's cells leave the factory at slightly different states of charge. The first time the pack reaches a full charge, the BMS bleeds the highest cells down through internal resistors so all four cells finish at the same voltage. That bleed-down causes the pack voltage to drop slightly, which the Fusion correctly reads as "the battery has lost a little charge," so it restarts a charge cycle, and the bank's mode LED returns to flashing red. Because the BMS is regulating internally, only a trickle of current flows. The cycle repeats until the cells are matched.
This is most visible on the Fusion 4-Bank because each bank's battery balances independently, so you may see different banks in different stages at the same time.
What To Do
1. Leave it plugged in. A new lithium pack needs an uninterrupted first charge to balance properly. Unplugging mid-cycle can leave cells out of sync for many cycles afterward.
2. Expect the first charge to take several extra hours. Plan on a full overnight charge for a brand-new battery.
3. Check back periodically. When balancing is complete, the bank holds solid green and stops drawing meaningful current.
4. From the second charge onward, the loop should be brief or gone.
When This Is Not Normal
This balancing behavior is specific to a brand-new lithium battery. Contact support if:
- The battery has been in service for more than a few full charge cycles and still loops solid green to flashing red.
- The Error notification LED (⊠) is flashing red; this is a polarity or voltage-mismatch issue, not balancing.
- The Low Voltage notification LED (⚠) is flashing red; use Force Start (hold the bank's MODE button 5 seconds).
- The bank stays solid red for more than a minute; see our article Fusion Charger Shows Solid Red but Isn't Charging.