What your battery test result means
Had your battery tested and not sure what the result means? This page explains how we test, what each result tells us, and what happens next, in plain language.
How we test
- 1Inspect the battery
First we inspect the battery itself: the terminals and the case, checking for damage, corrosion or leaks. What voids the warranty
- 2Check the charge
Next we measure the voltage to see how charged the battery is. If it's flat, it has to be charged before we can test it properly.
- 3Test the battery
Then we test how much starting power the battery still has. We use a digital tester and a load test, and on batteries with removable caps we also check each cell with a hydrometer.
- 4Test the car
With the battery in the car, we can also test the starter motor and the charging system (the alternator), so we know the problem isn't somewhere else.
Battery test results
The tester gives one of five results. Here's what each one means for you.
What the voltage tells us
This is measured with the engine off, after the battery has rested for a while. The voltage tells us how charged the battery is.
Why can't we test a flat battery? Below about 12.4 V, the tester can't tell the difference between a battery that is simply flat and one that is worn out. So we charge it first and then test it, which means you only replace a battery that really needs replacing. A battery that has dropped below about 10 V may not recover, even after a full charge.
Starter and charging results
These tests are done with the battery in the car and the engine running. They show whether the starter and alternator are working properly.
StarterIs the car cranking properly?
- Cranking voltage OK: the starter is working normally and nothing needs fixing.
- Cranking voltage low: the battery is fine, but the starter is drawing too much power. The starter motor or its wiring should be checked.
- Charge battery: the battery is too low to test the starter properly. We charge it first, then test again.
Charging systemIs the alternator putting power back?
- Normal: the voltage is right for your battery type (see below), so the alternator is doing its job.
- Low or none: the battery isn't being charged and will slowly go flat. Often a slipping belt, bad connection or worn alternator. Battery or alternator?
- High: the battery is being overcharged, which overheats it and can make the case swell. Usually a faulty voltage regulator.
Normal charging depends on the battery type
This is measured with the engine running. Each type of battery needs a slightly different charging voltage.
- Stop/start cars use smart charging. The car raises and lowers the charging voltage as you drive, so a lower reading isn't always a fault.
- AGM and EFB batteries need the right settings. The car's computer must know which battery is fitted, otherwise it can undercharge or overcharge it. That's why we check whether your car needs a BMS reset, battery registration or coding. Where required and supported, the applicable procedure is included with your Battery24 battery replacement. Battery types explained
A new battery won't fix a charging fault. If the alternator isn't charging properly, a new battery will soon go flat as well. That's why we check the car, not just the battery.
Good to know
We test any battery for free at our Brackenfell or Stellenbosch branch, while you wait.
The printed slip shows the test result and the voltage. Keep it, as it's useful if you ever need to make a claim.
To make a warranty claim, you'll need your invoice as proof of purchase. How warranty works
Want your battery tested?
Visit our Brackenfell or Stellenbosch branch for a free test. You don't need to buy a battery to have it tested.