Surprisingly affordable all-in-one testers offer all the necessary measurements to reliably distinguish counterfeit batteries from genuine ones and provide a general estimate of battery health. These testers are not only accurate but also versatile, making them ideal tools for both casual and more technical battery testing.
With a variety of models available, this section explores their capabilities and key differences, helping you find the right fit for your testing needs.
You can use these testers with non-rechargeable batteries as well, for example if you are curious about the overall quality of a particular vendor or battery series. Just be aware that a discharge test deplets the battery, so the specimen under test will be rendered useless after the test. Also you must disable charging mode with primary batteries so the tester won’t try and re-charge a non-rechargeable battery.
Overview
Most test devices provide the following core features:
- Discharge Test: Discharges a battery to a predefined (configurable) stop-voltage and logs the mAh (milliampere-hour) and mW (milliwatt-hour) capacity, making it easy to see how much usable energy a battery can deliver. While most batteries specify their total capacity in mAh, the true energy capacity is more accurately expressed in mWh, as this unit accounts for the voltage drop that occurs during discharge and is helpful when comparing different batteries.
- Charging and Test: Fully charges a battery while logging the mAh and mW transferred to the battery. Charging is typically limited to LiIon/LiPo battery types due to the charger ICs used; LiFePO₄ and other battery chemistries cannot be charged. Never use this mode with non-rechargeable batteries!
- Auto-Testing: Performs a complete test cycle, starting with fully charging the battery, then discharging it to determine capacity, and finally recharging it to prepare for use. Never use this mode with non-rechargeable batteries!
- Internal Resistance: Measures the battery’s internal resistance using a straightforward “multimeter method” (DC Test). Although this is not as precise as lab-grade methods, it’s useful for a quick estimate of battery health.
- External Connectors: While many devices are tailored for specific battery types (e.g., 18650 cells) and include compatible holders, most also feature screw terminals or other connectors to support various battery types. This flexibility allows for testing multiple battery formats without additional equipment.
Most testers are limited to 5V battery input, which is suitable for single-cell LiIon, LiPo, and LiFePO₄ cells, as well as AA/AAA cells. However, they are incompatible with multi-cell batteries (e.g., 12V LiFePO₄ or 7.4/11.2V LiPo packs). Connecting batteries with voltage above 5V will damage these devices.
Additional Tips for Using Battery Testers
- For Accurate Readings: Ensure the battery is correctly inserted, and allow a brief warm-up period for the tester.
- Testing Different Battery Chemistries: Stick to the chemistries specified for the device to avoid inaccurate readings or potential damage. Lithium-based chemistries (LiIon, LiPo, LiFePO₄) tend to work best with these testers.
- Non-Rechargeable Batteries: With non-rechargeable batteries, you may want to set the stop voltage to the lowest possible value to measure the total battery capacity. Make sure you are using a test mode that does not involve automatic charging!
- Interpreting Results: High internal resistance or low capacity often indicates a battery near the end of its lifespan. Frequent full charge-discharge cycles may reduce battery life for certain chemistries.
With these features and tips, you can make the most of your battery tester to gauge battery performance, identify counterfeit units, and extend the lifespan of quality batteries.
Differences
The test devices differ in the following aspects:
- Portability: Some testers reserve one battery bay solely for powering the measurement circuitry, making these devices independent from external USB power. When battery-powered, these testers can only perform discharge tests, as the supply battery doesn’t provide sufficient power to charge the battery under test. The downside is that one battery holder is unavailable for testing, even if the device is powered externally.
- Multiple Batteries: While some testers evaluate only one battery at a time, others can test multiple batteries simultaneously. This feature is crucial for testing larger numbers of batteries, as a complete discharge test can take several hours.
- Discharge Current: All testers use simple load resistors, so they cannot maintain a constant discharge current or allow adjustments. The discharge current is solely determined by the value of the load resistor and the gradual voltage drop as the battery discharges. Some testers have a maximum discharge current of 1A, while others limit it to 500mA, depending on the resistor used.
- Charge Current: Testers with charging capabilities rely on standard LiIon/LiPo charging ICs and are limited to charging these specific chemistries. The maximum charging current is generally capped at 1A, which is suitable for average 18650 cells but may be too high for smaller LiPo batteries.
- Fan Cooling: The load resistor dissipates energy as heat, and without cooling, it can become extremely hot. Some devices incorporate fans to help dissipate heat, protecting components and ensuring more stable readings.
- Missing Features: Certain devices have limited functionality, offering only discharge tests without charging capabilities. This limits their use, as they cannot perform automated tests where a battery is first fully charged before testing. Others only measure current state of charge, providing no discharge load or capacity testing.
Simple Improvements
Many devices can be enhanced with small upgrades:
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Additional Battery Types: By connecting additional battery holders to the screw terminals or solder pads, you can test various battery form factors beyond the device’s default configuration.
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Heat Sink: Adding a simple heat sink to the load resistors improves heat dissipation and reduces the risk of accidental burns. Without a heat sink or fan, these resistors can reach temperatures around 80°C; a heat sink can lower this to 60°C, and the vertical fins reduce the exposed hot surface.
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(content created Oct 28, 2024)