The main issue leading to malfunction, loss of capacity and diminished performance is improper charging. Charge current must be tapered down adaptively as charge voltage rises and the battery state approaches full. LiFePO4 batteries can not properly accept charge power once fully charged and prefer to sit idle while in a partial state of charge. You immediately risk damaging or reducing the life cycle of the battery when held completely charged or discharged for any period. You should avoid float, trickle and equalization charging when possible as these settings are designed to maintain Lead batteries in continuously fully charged states. When not in use, simply leave the battery in a partially charged state. You do not need to charge immediately after use unless they are completely discharged, or generally below 20%. 50% to 80% is ideal. To slow capacity loss over time, store in cooler dry conditions and charge up after six months to combat self discharge.
A LiFeP04 cell is essentially fully charged at 14.2V (3.55 Vpc). Charging above this voltage is acceptable but additional power gain is negligible and the risks of over cell charging due to cell imbalance becomes drastically elevated.
Low temperatures reduce the rate at which the battery can properly absorb current. Lithium ions, with no where to go, will begin piling up on the anode. This leads to irreversible Lithium metallic plating which will essentially begin instantaneously. Performance, output and lifecycle become diminished and the battery becomes increasingly less safe under stressful conditions.
We do not recommend charging below 0°C (32°F). It is safe to charge your battery between 0°C and 45°C without extra care.
The following rule of thumb applies when charging below 0°C to avoid non-reversible, capacity diminishing damage.
- Current must be reduced to:
- 0.1C max from -10°C to 0°C
- 0.05C max from -20°C to -10°C
Charging efficiency decreases above 40⁰C.
- Use only chargers that specific to LiFePO4 technology. Other Lithium chargers and Lead Chargers may not have the same charging requirements and can damage your cells.
- Use a Constant Current (CC) - Constant Voltage (CV) charger with cut-off at 14V - 14.6V.
- 0.2C charge rate, or less, is recommended to increase cycle longevity and decrease capacity loss.
- Up to 0.5C charge rate is generally acceptable.
- 1C is the maximum charge rate and it should not be utilized unless for short and infrequent periods.
- If you must charge with a charger designed for other battery types you must ensure it falls within proper current and voltage parameters.
- Do not float, trickle or equalize charge.
- If you are using a system that has a standard Float parameter, set it OFF or low as possible 12.8V - 13.6V
- If you are using a system that has a standard Absorption phase, set it OFF or as low as possible 0 - 10 mins. 14V - 14.4V
