charge time
| Battery Type | Typical Charge Time | Notes |
|---|---|---|
| Lead-acid | 8-12 hours | Slow charge time, can be faster with a fast charger. |
| LFP (Lithium Iron Phosphate) | 2-4 hours | Similar to lithium-ion but may take slightly longer. |
| Lithium-ion (Li-ion) | 1-3 hours | Fastest charging, especially with modern fast chargers. |
Common Rechargeable Battery Internal Resistance and Aging
| Battery Type | Nominal Voltage | Capacity Range | Internal Resistance (New) | Internal Resistance After ~200 Cycles | Notes / Applications |
|---|---|---|---|---|---|
| AA NiMH | 1.2V | 1800–2500 mAh | 20–50 mΩ | 30–80 mΩ | Consumer electronics, toys |
| AAA NiMH | 1.2V | 600–1200 mAh | 30–70 mΩ | 40–100 mΩ | Small electronics, remote controls |
| 18650 Li-ion | 3.6–3.7V | 2000–3500 mAh | 30–80 mΩ | 40–120 mΩ | Laptops, power banks, flashlights |
| High-drain 18650 Li-ion | 3.6–3.7V | 1500–3000 mAh | 15–30 mΩ | 25–50 mΩ | Power tools, e-cigarettes, high-current devices |
| 26650 Li-ion | 3.6–3.7V | 4000–6000 mAh | 10–40 mΩ | 20–60 mΩ | High-capacity flashlights, e-bikes |
| 12V Lead-Acid (SLA/AGM) | 12V | 7–20 Ah | 0.12–0.3 Ω | 0.15–0.4 Ω | Scooters, UPS, emergency lighting |
| 12V LiFePO4 | 12.8V | 10–20 Ah | 5–20 mΩ | 10–30 mΩ | E-bikes, solar storage, UPS |
| 9V NiMH | 8.4–9V | 150–300 mAh | 150–300 mΩ | 200–400 mΩ | Smoke detectors, small electronics |
| NiCd AA | 1.2V | 600–1000 mAh | 30–100 mΩ | 50–150 mΩ | Older toys, cordless phones |
| LiPo (3.7V per cell) | 3.7V | 500–5000 mAh | 20–100 mΩ | 40–150 mΩ | Drones, RC cars, FPV drones |
Notes on Internal Resistance Change:
- Internal resistance increases gradually with usage cycles and charging/discharging.
- The amount of increase depends on:
- Battery chemistry and quality
- Depth of discharge and charging rate
- Temperature and storage conditions
- Higher resistance results in lower peak current capability and slightly reduced capacity over time.
Types
Sodium-ion Battery
A common question is: "Since we already have Lithium Iron Phosphate (LFP) and Ternary Lithium batteries, why develop Sodium-ion batteries?"
Advantages (Key Strengths)
- Extremely Low Cost & Resource Independence: Lithium resources are scarce with volatile prices, while sodium resources (from table salt) are abundant on Earth. Once scaled up, costs can be approximately 30% lower than LFP.
- Superior Low-Temperature Performance: Lithium batteries often struggle in outdoor temperatures of -20°C (rapid power drop, slow charging). Sodium-ion batteries can still maintain over 80% discharge capacity at -20°C, and charging speeds remain largely unaffected, making them ideal for cold climates.
- Higher Safety: Lower internal resistance and higher thermal runaway temperature make them less prone to fire or explosion.
Disadvantages
- Lower Energy Density: The energy density of CATL's 1st/2nd generation sodium-ion batteries is around 160 Wh/kg. While this matches some low-end LFP batteries, it is still far behind ternary lithium batteries. Consequently, they are not suitable for high-end EVs requiring long range (e.g., over 700km).