It can show that a battery is clearly dead, and very little else. Resting voltage says nothing about capacity, and a pack that reads correctly can still collapse the moment a real load is applied — which is what a load test or a counted discharge reveals.
A multimeter is indispensable and is the wrong instrument for the question people most often point it at.
What it answers well
Whether voltage is present, where it is being lost along a run, and whether a connection is the cause of a voltage drop under load. Measured at two points simultaneously, it locates a bad joint faster than anything else on the bench.
What it cannot answer
How much energy is stored. Voltage is a symptom that depends on recent history, temperature and load, and on some chemistries it barely moves across most of the usable range. A confident reading on a nearly empty LiFePO4 pack is routine.
What does answer it
A counted discharge: charge fully, run a known load, total the energy out. A shunt monitor does this during ordinary use, and a bench load tester does it deliberately. Either produces a quantity; the multimeter produces an indication.
The measurement that is genuinely worth taking
Voltage at the battery and at the load, at the same moment, with the load running. The difference between the two is the installation, and it is the fault most often blamed on the battery.
What people ask before they order
What does a load test add?
It applies a known current and watches the voltage, which exposes internal resistance. It is a quick screening test rather than a capacity measurement, and it is what distinguishes a tired battery from a flat one.
Is internal resistance a useful number?
As a trend for a given pack, yes — a rising figure over time indicates ageing. As an absolute value compared between different products, much less so.
Last reviewed 16 September 2026