Why Does My 43V Battery Show 100% While It's Still Charging?Updated 3 hours ago
If you have a 43V Foil Drive Battery, you may notice that both the Battery Caddy and the Foil Drive App display 100% State of Charge while the battery remains connected to the charger and is still actively charging.
This is completely normal and is part of how lithium battery charging and the Battery Management System (BMS) work.
Why does this happen?
The Battery Management System (BMS) continuously estimates the battery's State of Charge using several factors, including:
- Battery voltage
- Current flow
- Battery behaviour during charging and discharging
As the battery approaches full charge, the charging process slows significantly to protect the battery and maximise its lifespan.
Although the app may display 100%, the charger may still be:
- Balancing the individual battery cells
- Gently topping up the final portion of the battery's capacity
This ensures every cell reaches the correct voltage before charging is complete.
A simple analogy
Think of charging your battery like filling a car with fuel.
Most of the fuel goes in quickly, but as the tank nears full, the fuel pump automatically clicking off when the tank is essentially full.
If you've ever gently squeezed the nozzle after the first click, you'll know you can often add a small amount more before the tank is completely full.
Lithium batteries behave in a similar way.
The Foil Drive App and Battery Caddy display 100% once the battery is effectively full for normal use, while the charger continues the final balancing and top-up process in the background.
Why doesn't the percentage keep increasing?
The battery percentage is an estimate of usable charge rather than a direct measurement of every individual cell.
Once the battery reaches its usable full capacity, the displayed State of Charge remains at 100%, even though the charger may still be performing the final balancing process.
This is expected behaviour and does not indicate a fault with the battery, charger or Battery Caddy.
A closer look at your battery
Unlike many battery-powered products that only display a simple percentage, the Foil Drive App provides detailed battery information, including:
- State of Charge (%)
- Total battery voltage
- Individual cell voltages
- Remaining amp-hours (Ah)
- Charging status
- Cell balancing information
This provides a real "look under the hood" of what the battery is doing internally. Rather than simply showing Full or Empty, the app allows you to monitor the health and behaviour of the individual cells that make up the battery pack.
Is this normal?
Yes.
If your 43V battery shows 100% while it remains connected to the charger, this simply means the battery has reached its usable full capacity and the charger is completing the final balancing and top-up process.
You can remove the battery from the charger once it reaches 100% charge, but if you're not in a rush, leave it connected to the charger to finish the final balance charge.