Battery testing should give you a clear answer. However, the words on the battery label, tester screen or printed result might make that answer harder to understand than it should be.
For instance, what’s the difference between CCA and reserve capacity? Does ‘Good Battery’ mean the battery is fully charged and good to go? Why might the tester tell you to charge and retest instead of giving you a clear pass or fail?
This Midtronics testing jargon buster explains the terms you’re most likely to see when testing starter batteries and vehicle electrical systems or when browsing our website.
Cold cranking amps
The battery’s rated cold-starting power
Cold cranking amps, or CCA, show how much current a starter battery can supply in cold conditions. The CCA figure on the label is the battery’s rating when new. Enter this figure into the tester so it can compare the battery’s current starting ability with the performance it should provide.
Rated CCA is the figure printed on the battery label. Measured CCA is the tester’s estimate of what the battery can provide now.
Reserve capacity
How long the battery can support an electrical load
Reserve capacity shows how long a fully charged battery can supply a set electrical load before its voltage falls too low. A battery can often still start the engine but have poor reserve capacity. This can lead to low-voltage faults and, eventually, non-starts.
Ampere-hours
The battery’s capacity over time
Ampere-hours, or Ah, show how much current a battery can provide over a set period. For example, a 100 Ah battery could theoretically provide 5 amps for 20 hours under specified test conditions.
It’s one of the main battery ratings, alongside CCA, but it measures capacity rather than starting power. When testing, always enter the rating that the tester asks for, using the battery label.
Conductance
A measurement linked to the condition of the battery plates
Conductance shows how easily electrical current can flow through the battery. Ageing, corrosion, sulphation and plate damage make this harder. Midtronics testers use conductance to check whether the battery can still provide enough power to start the engine. They do this without applying the long, heavy load used in a traditional load test.
Conductance Profiling
Midtronics technology that looks beyond a basic CCA result
Conductance Profiling™ is a patented Midtronics technology that combines conductance testing with a wider check of cranking ability and reserve capacity, as mentioned above. It gives you a fuller picture of the battery’s state of health, including whether it can still start the engine and support electrical loads.
State of charge
How much charge the battery contains right now
State of charge, or SoC, tells you how ‘full’ the battery is. It doesn’t, however, tell you whether the battery is healthy. In other words, a good battery can have a low SoC after short journeys, long periods of standing or an electrical drain. An ageing battery can be fully charged (full SoC) but still have poor SoH and fail the test.
State of health
The battery’s remaining ability to ‘do its job’
State of health, or SoH, compares the battery’s current performance with its expected performance when new. The tester may use cranking ability, conductance, reserve capacity and other data to work this number out, which may be shown as a percentage. Use SoH as one part of the overall test result. Don’t rely on it alone to decide whether to replace a battery.
Dynamic charge acceptance
How well the battery can accept incoming charge
Dynamic charge acceptance, or DCA, shows how well the battery can take in charge as conditions change. This is especially important on start-stop and smart-charging vehicles, where the battery may have only short periods to recharge. It may still start the engine but fail to recover (recharge) during normal vehicle use.
Battery type
The battery technology you select before testing
Depending on the equipment, you may see battery types such as:
- Flooded lead-acid (FLA)
- Enhanced flooded battery (EFB)
- Absorbent glass mat (AGM)
- Spiral-wound AGM
- Gel
- Lithium iron phosphate (not all testers support this battery type yet)
If you select the wrong battery type on the tester, it will use the wrong test rules and give you an unreliable result. Check the battery label. Don’t guess from the battery case, vehicle type or application.
Battery rating standard
The standard used for the battery’s stated rating
Battery labels may show EN, SAE, IEC, DIN, EN2, JIS or another rating standard.
- EN – European Norm, used across Europe.
- SAE – SAE International standard, mainly used in North America.
- IEC – International Electrotechnical Commission standard.
- DIN – German standard from the German Institute for Standardisation.
- EN2 – An alternative European test method.
- JIS – Japanese Industrial Standards.
Each standard uses different test conditions, so a 600-amp EN rating isn’t the same as a 600-amp SAE rating. Enter the exact rating and standard shown on the battery label.
Charge and retest
An instruction to charge the battery before making a decision
‘Charge & Retest’ isn’t a pass or fail result. It means the battery’s charge is too low for the tester to make a reliable decision. Charge the battery using the correct process, then test it again. If the battery keeps losing charge, check the vehicle for an underlying fault. If it still won’t accept charge, carry out further diagnosis and follow the tester’s decision.
Good Battery, Good Recharge and Replace Battery
Test decisions that tell you what to do next
- ‘Good Battery’ means the battery has good cranking performance and, where tested, good reserve capacity. It doesn’t guarantee how long the battery will last or mean it’s charged to exactly 100%.
- ‘Good Recharge’ means the battery has good cranking performance, but its charge level is low. Fully charge it and check why it became discharged.
- ‘Replace Battery’ means the battery has poor cranking performance, low reserve capacity or both. Follow the tester’s instructions and check the connections before replacing it.
Surface charge
Extra charge that can temporarily raise the voltage reading
Surface charge can remain on the battery plates after the alternator has been charging the battery or after you disconnect an external charger. This temporary rise in voltage happens because the chemical conditions near the battery plates take time to settle after charging.
Basically, surface charge makes the battery voltage look higher than it really is. Follow the tester’s instructions to remove it. You may need to apply a short electrical load or leave the battery to rest before testing again.
Open-circuit voltage
The battery voltage when no load is being applied
Open-circuit voltage is the voltage you measure when the battery isn’t being charged or used. A fully charged, rested 12-volt lead-acid battery will read around 12.6 volts. This can help you estimate state of charge, but it won’t give you a full diagnosis. A battery may show normal voltage and still fail under load.
Cranking voltage
The battery voltage while the engine is starting
Cranking voltage is the voltage measured while the starter motor turns the engine. A large voltage drop may point to a weak battery, poor connections, damaged cables or a starter fault. Don’t replace the battery based on cranking voltage alone. Test the battery and inspect the full starting circuit. You might need a new starter motor, cable, connector or terminal instead.
Charging voltage
The voltage supplied while the engine is running
Charging voltage is the system voltage produced while the alternator is working. It powers the vehicle’s electrical loads and recharges the battery. A low result may point to poor alternator output, cable resistance, bad connections or demand exceeding the alternator’s output. A high result (unlikely) may indicate a regulator, wiring, sensing or bad earth and could damage the battery. Always follow the vehicle manufacturer’s figures, especially on smart-charging systems.
Ripple
Unwanted changes in the alternator’s electrical output
Alternator ripple is a change in voltage caused by the alternator’s AC output not being fully converted into DC. Too much ripple points to a damaged diode or another alternator fault. It is likely to affect battery charging and vehicle electronics.
In-vehicle test
A battery test carried out while the battery’s still connected
An in-vehicle test lets you check the battery without removing it. This saves time and can provide a more representative real-world test, but the tester may detect interference from connected vehicle systems. Make sure the ignition and electrical loads are off. Follow the tester’s instructions and connect directly to the correct battery posts or test points.
Out-of-vehicle test
A battery test carried out with the battery disconnected
An out-of-vehicle test involves removing the battery. It means you don’t have to account for the effect of the vehicle’s electrical system and can analyse the battery alone. It can help when an in-vehicle result isn’t clear. However, disconnecting the battery may affect vehicle settings, security systems or control units. Follow the correct shutdown and reconnection process before you remove the battery terminals.
Test code
A code that records or confirms the test result
Some Midtronics testers create a test code after completing the battery or system test. You can use this code as a record of the result. It may also support warranty decisions, workshop reports or fleet maintenance records. Make sure you enter the correct vehicle and battery details before testing.
ROBIS
An online system for storing and reviewing battery test data
ROBIS collects battery and electrical-system test data from compatible equipment. It helps you see whether technicians are following the correct testing process. You can also use it to review results, identify repeat faults, track trends and manage battery maintenance across several vehicles, workshops or locations.
Turn individual test results into useful battery data
Alongside the jargon, your inputs also matter. Select the correct battery type, rating, standard, test location and vehicle details before you begin. A tester can only give you a reliable result when you give it the right information.
Here at Rotronics, we supply professional Midtronics battery and electrical-system testers. We also help you get set up with ROBIS. Get in touch with our team so we can better understand your fleet, dealership or fast-fit workshop. We’ll recommend the most appropriate testing and charging solutions for your operations.
