Battery testers

Before you replace a battery, it pays to know whether it is truly worn or simply flat. A battery tester settles that in seconds: it reads voltage, estimates real cranking ability against the rated figure and, on many models, checks the alternator as well.

We sell testers from MOTOBATT and FULBAT for 12 V car, motorcycle and marine batteries.

What a tester measures

• Resting voltage: shows state of charge. With the engine off for several hours, a full 12 V lead battery sits around 12.6–12.8 V; near 12.2 V it is half charged.
• Conductance or internal resistance: electronic testers use it to estimate available cold cranking amps (CCA, EN, SAE or DIN) and compare them with the label. That comparison gives the state of health.
• Cranking test: logs how far voltage drops while the engine turns over. A very deep dip points to a weak battery or a starter motor drawing too much.
• Charging system: with the engine running, voltage should fall within the range the vehicle maker specifies, usually above 13.5 V and not beyond roughly 14.8 V.

Reading the result

Low voltage with good health means the battery only needs a full charge from a suitable battery charger. If measured CCA stays far below the rating after charging, capacity has gone and replacement is due. Always retest with the battery charged: a reading taken on a flat battery is not conclusive.

When owning one makes sense

Workshops, fleets, motorcycle dealers and anyone with several vehicles will get good use from one. It flags a failing battery before winter and avoids changing one that is still fine. If a replacement is needed, browse car batteries or the MOTOBATT brand.

Battery tester FAQ

Will a multimeter do the same job?

A multimeter reads voltage but cannot tell how much current the battery can deliver. A sulphated battery can show 12.6 V and still fail to crank.

Do they work with AGM, EFB and lithium batteries?

Electronic testers usually let you choose between flooded, AGM, EFB and GEL. For lithium, check the product sheet for compatibility.

Must the battery be disconnected to test it?

Usually not. Switch off loads and wait a while so surface charge does not distort the reading.