Lately our factory develops one type of battery tester.It not only has full system diagnostic function,I/M ready status .Its highlights is that it has battery testing function.It can go on battery internal resistance test，battery remaining capacity test，battery health test，battery voltage test，battery voltage curve monitoring.Let’s see how much benefit the battery test function can bring to us.
A. Function of Battery Internal Resistance Test
The battery internal resistance test plays a vital role in assessing the health and performance degradation of a battery. It provides a quick and effective way to understand whether a battery is aging or failing.
Main Functions:
1.Evaluate Battery Health (SOH)
1.Higher internal resistance means more aging.
2.A new battery has low internal resistance and high discharge capability; an aging battery shows higher resistance.
2.Predict Battery Lifespan
1.Tracking internal resistance changes over time helps forecast when replacement is needed.
2.Rapidly rising resistance usually indicates shorter life.
3.Detect Hidden Faults
1.A battery can have normal voltage but still fail under load if its internal resistance is high.
2.Resistance testing helps identify these “false healthy” batteries.
4.Identify Weak Cells in Battery Packs
1.In a pack, one defective cell can reduce overall performance.
2.Resistance testing quickly locates problematic cells.
5.Improve Efficiency and Safety
1.High resistance causes heat and energy loss, and may lead to swelling or leakage.
2.Early detection prevents damage and safety hazards.
Typical Reference:
*New battery: 3–10 mΩ (depending on type and capacity)
*When internal resistance doubles from its original value → performance decline, replacement recommended.
B. Function of Battery Remaining Capacity Test (SoC)
The State of Charge (SoC) test measures how much usable energy remains in a battery — similar to a fuel gauge for electric power.
Main Functions:
1.Know How Much Power Is Left
1,Shows real-time usable energy.
2,Helps plan recharging and prevent unexpected power loss.
2.Prevent Overdischarge and Overcharge
1,Overdischarge permanently damages a battery; overcharge risks overheating or explosion.
2,Accurate SoC monitoring enables safer and longer battery life.
3.Estimate Remaining Runtime
Predicts how long a device or vehicle can continue operating under current load.
4.Optimize Charging Strategy
1,Different SoC levels require different charging currents and voltages.
2,Improves efficiency and reduces energy loss.
5.Assist Health Evaluation (SOH)
Combined with voltage, resistance, and temperature data, SoC helps assess degradation and remaining useful life (RUL).
6.Ensure System Stability
Balances each cell in a battery pack, preventing overcharge or overdischarge in any single cell.
C. Function of Battery Health Test (SOH)
The State of Health (SOH) test evaluates the overall condition and lifespan of a battery. It indicates how much of its original capacity and performance remains.
Main Functions:
1.Assess Overall Battery Performance
1,Based on capacity, internal resistance, voltage behavior, and temperature characteristics.
2,A high SOH = good performance; a low SOH = degraded performance.
2.Predict Battery Replacement Time
1,SOH (expressed in %) predicts how much life remains.
2,When below 70–80%, replacement is usually recommended.
3.Prevent Failures and Safety Risks
1,Aging batteries may overheat, swell, or leak.
2,SOH testing identifies these risks early.
4.Improve Maintenance and Management
1,Helps optimize pack balancing, extend system life, and improve efficiency.
5.Provide Warranty Evidence
1,SOH reports clarify whether failure is due to wear, misuse, or manufacturing defect.
6.Support Intelligent BMS Optimization
Battery Management Systems adjust charge/discharge behavior using SOH data for better safety and longevity.
Typical Interpretation:
| SOH Value | Condition | Recommendation |
| ≥ 90% | Healthy | Normal use |
| 70–89% | Mild degradation | Monitor regularly |
| 50–69% | Noticeable decline | Plan replacement |
| < 50% | Severely degraded | Replace immediately |
D. Function of Battery Voltage Test
The voltage test is the most basic and commonly used diagnostic method. It measures the potential difference between battery terminals to determine its operating condition.
Main Functions:
1.Check Current Charge Level
1,Voltage directly reflects how much energy remains.
2,Example (12V lead-acid battery):
≥ 12.6V → Fully charged
≈ 12.2V → Medium charge
≤ 12.0V → Low charge, recharge needed
< 11.8V → Severely discharged
2.Identify Faults or Aging
If voltage drops quickly after charging, the battery may suffer from self-discharge or internal short circuit.
3.Evaluate Charging/Discharging System
In vehicles:
Before start → battery condition
During start → cranking performance
After start → alternator function (13.8–14.5V typical)
4.Detect Imbalance in Battery Packs
Comparing each cell’s voltage reveals imbalance or weak cells.
5.Provide Baseline Data for Further Testing
Voltage data is essential before internal resistance, SoH, or SoC testing.
Summary:
⚡ Voltage testing = the “thermometer” of a battery
It quickly indicates charge level, abnormalities, and operational status.
E. Function of Battery Voltage Curve Monitoring
Voltage curve monitoring continuously records how voltage changes during charging, discharging, and rest. It’s a dynamic analysis that reveals performance trends, degradation, and safety issues.
Main Functions:
1.Real-Time Operating Insight
1,Shows voltage variation throughout different phases.
2,Detects sudden drops, irregular spikes, or abnormal charging behavior.
2.Assess Battery Health (SOH)
1,Healthy batteries have smooth, stable voltage curves.
2,Aging batteries show shortened plateaus, sudden drops, or overshoots.
4.Optimize Charging/Discharging Strategy
Enables BMS to dynamically adjust current and voltage thresholds for better efficiency and lifespan.
5.Evaluate Capacity and Degradation
1The length and shape of the discharge plateau indicate capacity and performance decline.
6.Identify System Faults and Safety Risks
1,Irregular voltage curves may signal imbalance, overheating, or control issues.
2,Early warning prevents accidents.
Comparison:
| Item | Single Voltage Test | Voltage Curve Monitoring |
| Data Type | Single value | Continuous time-based data |
| Purpose | Snapshot | Trend and performance analysis |
| Fault Detection | Limited | Early warning possible |
| Use Case | Quick test | Long-term monitoring & diagnostics |
Summary:
⚡ Voltage curve monitoring = the “ECG of a battery”
It visualizes the battery’s heartbeat — revealing health trends, early faults, and optimization opportunities.
Of course,if you want to learn more details about the battery tester,you can visit the link https://www.sanytek.com/product/hotselling-car-battery-tester-with-full-system-diagnostic-functioni-m-ready-status/ for more.Or you can send your information to our email :info@sanytek.com
When you own one battery tester,you will know your car batteries status in advance and give you very good repairing advice .In the end,it helps you save time ,money and energy to search solution blindly.