Voltage Sag Testing

Measuring what a pack does under load, not at rest.

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Measuring what a pack does under load, not at rest.

Measuring sag under a known load

Measure at the terminals, not at the load, or the cable becomes part of the measurement.

Interpreting the result

Compare groups of cells under the same load; the spread matters more than the absolute number.

Voltage & sizing questions

Short answers to the ones that come up most.

How do I choose a voltage?

Set by the equipment — 12V small loads, 24V light traction, 48V storage and traction.

How do I work out runtime?

Ah x V = Wh, divided by the real load, minus losses.

Why 12.8V?

Four 3.2V LFP cells in series.

What is C-rate?

Current relative to capacity.

Series different batteries?

No — same model, capacity and age.

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