A 72V battery voltage chart details the voltage parameters of 72V battery systems across charge/discharge cycles. For lead-acid batteries, full charge voltage peaks at 81-87V (6x12V cells at 13.5-14.5V/cell), while lithium-ion variants like NMC/LiFePO4 reach 84V (20S) or 87.6V (24S). Discharge cutoff occurs at 63V (lead-acid) or 65-68V (lithium), with real-world operation typically between 72-75V under load.
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How does voltage vary during discharge for 72V batteries?
72V batteries exhibit voltage sag proportional to load. Lead-acid systems drop from 81V (full) to ~75V at 50% capacity, reaching 63V cutoff. Lithium variants maintain tighter voltage curves—LiFePO4 stays above 72V until 20% remaining. Pro Tip: Use 10% voltage bands for capacity estimation (e.g., 84V=100%, 76V=20% in NMC).
The discharge curve isn’t linear—voltage plummets rapidly below 25% charge. For example, a 72V LiFePO4 pack might hold 78V at 50% load but drop to 68V within 10 minutes of heavy acceleration. Transitioning from partial to full discharge, lead-acid batteries lose ~0.5V per 10Ah consumed, while lithium systems show sharper drops near empty. Why does this matter? Voltage-based fuel gauges become unreliable below 30% charge without coulomb counting.
| State of Charge | Lead-Acid Voltage | LiFePO4 Voltage |
|---|---|---|
| 100% | 81V | 87.6V |
| 50% | 75V | 79.2V |
| 20% | 68V | 73V |
What are the full-charge voltages for different 72V battery types?
Full-charge voltages depend on chemistry: lead-acid peaks at 81V (13.5V/cell), NMC lithium at 84V (4.2V/cell), and LiFePO4 at 87.6V (3.65V/cell). Overcharging beyond these thresholds causes electrolyte breakdown in lead-acid or lithium plating in Li-ion cells.
Chargers must match battery chemistry—a LiFePO4 charger set to 87.6V would overcharge lead-acid within minutes. Practically speaking, 72V lithium packs require ±0.5% voltage precision. For instance, a 20S LiFePO4 configuration needs 3.65V±0.02V per cell balancing. Real-world example: Charging a 72V 50Ah lead-acid battery to 87V (14.5V/cell) accelerates water loss, reducing lifespan by 40-60 cycles.
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How does temperature affect 72V battery voltage?
Voltage drops 0.3-0.4% per °C below 25°C in lithium batteries—a 72V NMC pack at -10°C reads 82V instead of 84V when full. Lead-acid suffers worse cold performance: 81V full charge at 25°C becomes 78V at 0°C. Always temperature-compensate charging voltages in extreme climates.
What voltage indicates 72V battery failure?
Cell imbalance ≥0.5V in lithium packs or post-charge sag >10% signals failure. A 72V lead-acid battery dipping to 70V immediately after charging indicates sulfated cells. Lithium batteries with ≥5mV variance between cells during charging require immediate balancing.
| Failure Mode | Lead-Acid Voltage Sign | Lithium Voltage Sign |
|---|---|---|
| Sulfation/Imbalance | Cell ≤12.8V after charge | Cell ≤3.2V under load |
| Internal Short | Rapid self-discharge to ≤60V | Pack voltage drops 5V/hour |
Redway Battery Expert Insight
FAQs
No—lithium requires higher voltage precision (84V±0.5V vs. 81V±2V). Mismatched chargers risk undercharge or BMS shutdowns.
Why does my 72V battery show 75V after full charge?
Normal for lead-acid resting voltage—surface charge dissipates to 81V→78V within 24 hours. Lithium should maintain 84V/87.6V unless imbalanced.
Max Voltage for 72V Lithium-Ion Battery
