What is the voltage of a hybrid battery cell?

The voltage per cell in a hybrid battery depends on the chemistry: nickel-metal hydride (NiMH) cells are typically about 1.2 volts per cell, while lithium-ion (Li-ion) cells run about 3.6–3.7 volts per cell.

In practice, hybrids string many cells in series to form a high-voltage pack that powers the electric motor. NiMH packs in traditional hybrids generally sit in the 100–200 volt range (with examples like the Toyota Prius around 144 V), while Li-ion packs used in newer hybrids and plug‑in hybrids typically operate in the 200–400 volt range (with plug‑ins often approaching 360 volts or higher, depending on design).

Cell chemistry and nominal voltages

Nickel-metal hydride (NiMH)

NiMH cells used in many traditional hybrids have a nominal voltage of about 1.2 volts per cell. They typically operate within roughly 1.0 to 1.4 volts per cell, influenced by temperature and state of charge.

NiMH cell voltage in practice

• Nominal cell voltage: 1.2 V per NiMH cell


• Typical operating range: approximately 1.0–1.4 V per cell


• Common pack voltages: many NiMH HEV packs in the 100–200 V nominal range (e.g., Prius around 144 V)


• Cell count per pack: dozens of cells arranged in series/parallel to achieve target pack voltage and capacity

Conclusion: NiMH cells carry modest voltage per cell, but their series configuration yields the practical high-voltage supply for traditional hybrids.

Lithium-ion (Li-ion)

Li-ion cells used in hybrids generally have a nominal voltage of 3.6–3.7 V per cell. The typical full-charge voltage is around 4.1–4.2 V per cell, with some chemistries (such as LFP) having lower maximum voltages.

Li-ion cell voltage in practice

• Nominal voltage per cell: 3.6–3.7 V (common for NMC/NCA chemistries)


• Maximum charge voltage per cell: about 4.1–4.2 V (depends on chemistry)


• Typical HEV pack voltage: roughly 200–300 V; plug-in hybrids: about 300–400+ V


• Common pack configurations: dozens to hundreds of cells in series to reach target pack voltage; common chemistries include NMC, NCA, and occasionally LFP

Conclusion: Li-ion packs deliver higher voltage per cell, allowing a higher-energy pack with fewer cells in some designs, which can reduce weight and improve efficiency in modern hybrids.

Summary

In short, the voltage of a hybrid battery cell is dictated by chemistry: NiMH cells are around 1.2 volts each, while Li-ion cells are around 3.6–3.7 volts each. The overall pack voltage is the sum of many cells in series, typically placing NiMH-based packs in the 100–200 V range and Li-ion-based packs in the 200–400 V range, with plug-in hybrids often at the higher end of that spectrum. For precise figures, consult the vehicle’s specifications from the manufacturer.

Are all battery cells 1.5 V?

Voltage difference: Primary batteries typically have a nominal voltage of 1.5v when fresh, while rechargeable batteries like lithium-ion, NiMH or NiCd batteries have a nominal voltage of 1.2v. This voltage difference may affect the performance of certain devices.

Is 14.7 volts too high on a battery?

A 14.7-volt reading is generally not too high for a 12-volt lead-acid battery while it's being charged, as it's within the typical range for a healthy alternator or charger, though it is at the upper end. However, if the voltage stays at or above 14.7 volts for a prolonged period after the battery is fully charged, or if readings are consistently above 15 volts, it could indicate overcharging and lead to damage. 
This video explains the ideal voltage range for a car battery: 1mOBD InsightsYouTube · Feb 13, 2025
What to know about 14.7-volt readings

• While running: A reading of 14.7 volts is common and usually indicates the charging system is working correctly to keep the battery full while the engine is on. 
• Maximum limit: Voltages above 15 volts are a strong indicator of overcharging. 
• Monitor the voltage: If you see 14.7 volts, monitor the charging process to ensure the voltage drops to a lower, maintenance level once the battery is full. 
• Potential for damage: Prolonged overcharging can cause the battery to lose water and shorten its lifespan. 

This video demonstrates what a charging voltage too high can look like: 56s1A Auto: Repair Tips & Secrets Only Mechanics KnowYouTube · May 11, 2020
When to be concerned

• If you consistently see a reading above 15 volts. 
• If the voltage remains at 14.7 volts for a long time, even after the car has been running for a while. 
• If you notice other symptoms of overcharging, such as a glowing check engine light or a rotten egg smell. 

If you are concerned about your battery's voltage, it is best to have a professional check the charging system for you.

What is the voltage of a Toyota hybrid cell?

A single Toyota hybrid battery cell has a nominal voltage of 1.2V1.2 cap V1.2𝑉, but the cells are connected in modules, and the voltage can vary depending on the model and state of charge. For example, a common hybrid battery module (containing six cells) has a nominal voltage of 7.2V7.2 cap V7.2𝑉 and can be fully charged to about 8.2V8.2 cap V8.2𝑉. 
Cell and module voltage

• Individual cell: A single NiMH (nickel-metal hydride) cell has a nominal voltage of 1.2V1.2 cap V1.2𝑉. 
• Battery module: Modules, which are made of multiple cells, have different voltages. 
  • Nominal voltage: 7.2V7.2 cap V7.2𝑉 (for a module with six 1.2V1.2 cap V1.2𝑉 cells). 
  • Fully charged: 8.2V8.2 cap V8.2𝑉. 
  • Fully discharged: 6V6 cap V6𝑉. 
• High-voltage pack: The total high-voltage battery pack is made up of many modules. For example, a Toyota Prius high-voltage battery can have a total voltage of over 200V200 cap V200𝑉. 

Why voltage readings are important

• Monitoring health: Monitoring the voltage of individual modules is a way to check for a failing battery.
• Identifying issues: If one battery module's voltage drops significantly when the engine is off, it may indicate a faulty cell within that module. 

Is there a way to test a hybrid battery?

Yes, you can test a hybrid battery, but it's a complex process that is best performed by a professional with the right tools. For a DIY approach, you can look for signs of a weakening battery like reduced fuel efficiency and monitor performance with an OBD-II scanner, which can read data like voltage and charge cycles. However, to test the actual capacity and individual cells, a deep dive with specialized equipment is necessary. 
Professional testing

• Scan tool: A professional mechanic can use a scan tool to access the vehicle's computer and get a real-time snapshot of the battery's performance, including voltage, temperature, and charge cycles. 
• Deep discharge testing: Professionals can deep discharge the battery and measure the voltage of individual modules. If they don't discharge equally, it indicates an imbalance or weak cells. 
• Load testing: Due to the high voltage, load testing a hybrid battery as a whole is not possible in the same way as a 12-volt battery, but testing individual cells under load can be done. 

This video explains why testing a hybrid battery is difficult and demonstrates how a professional tests individual cells: 43sThe Car Care NutYouTube · Jan 11, 2025
DIY checks and observation

• Monitor fuel economy: A significant and sudden drop in MPG can be a subtle indicator that the battery isn't functioning efficiently. 
• Watch the dashboard: Look for warning lights or messages like "Check Hybrid System" or "Service Hybrid Battery". 
• Use an OBD-II scanner: Purchase or borrow an OBD-II scanner that is compatible with your hybrid model. 
  • Plug it in and check for any Diagnostic Trouble Codes (DTCs) related to the hybrid battery. 
  • Some scanners allow you to monitor real-time data like the battery's state of charge. 
• Capacity estimation (advanced DIY): With an appropriate scanner and by using a known load, you can estimate the battery's capacity by timing how long it takes to discharge from a specific state (e.g., 80% to 20%). 

This video demonstrates how to use the diagnostic mode on a Toyota Prius to check the hybrid battery's health: 55shybrid32494YouTube · Sep 5, 2018
Important safety note

• Hybrid batteries operate at dangerously high voltages.
• Testing and working on hybrid batteries should only be performed by trained professionals.