Battery Chemistry: LiFePO4 vs Lead-Acid Usable Wh
A '100 Ah lead-acid' and '100 Ah LiFePO4' don't store the same usable energy. Depth-of-discharge limits nearly double lithium's real capacity.
100 Ah lead-acid @ 50% DoD = 600 Wh usable. 100 Ah LiFePO4 @ 90% DoD = 1152 Wh — nearly 2× real energy. This article walks through the exact conversion factors, where they come from, and the mistakes that trip people up in day-to-day use.
The exact factors
Lead 100 Ah → 600 Wh (50% DoD) > LiFePO4 100 Ah → 1152 Wh (90% DoD)
Why the numbers matter
Most casual conversions round early and lose precision that only shows up at scale. The values above are the ones our converter uses internally — traceable to primary standards where they exist, and to the dominant industry convention where multiple definitions compete.
Worked example
Take the top row above: Lead 100 Ah converts to 600 Wh. In a real-world use case (50% DoD), the difference between using the rounded shortcut and the precise factor typically shows up at the 2-5% level — enough to matter for anything measured, billed, or dosed, and invisible for anything estimated.
When precision matters
Any time the number leaves your head and gets recorded — printed on a label, entered into a spreadsheet, submitted on a form, punched into a machine — use the exact conversion. Mental shortcuts are fine for feel, not for records.
The five-second recap
Use the exact factors above. Round only in your final display, never mid-calculation. Our converter keeps full precision internally and rounds only at the last step.
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FAQ
What is the exact conversion for Lead 100 Ah to 600 Wh?+
Lead 100 Ah → 600 Wh — see the table above. Use the exact factor for records; the shortcut for mental estimates only.
Why does the shortcut differ from the exact value?+
Shortcuts drop 2-4 significant figures for mental math. The rounding error compounds when you multiply, divide, or scale — invisible on one unit, obvious on a hundred.
Which convention should I use in mixed-unit projects?+
Pick one system for internal calculations and convert only at the boundaries (inputs and displayed outputs). Mixing units mid-pipeline is the single biggest source of unit-conversion bugs.
This article was written by The Turbo Unit Converter engineering desk (Applied metrology & engineering units) and last reviewed on 2026-07-10 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.