Free, and what a membership adds

Working out the pack is free, unlimited and needs no account. A membership keeps the design.

What the money buys

Keeping your work. Sign in with a Leumas membership and an accepted design saves to your account, up to fifty of them, readable from any browser you sign in on. Revision history and a bill of materials export are specified but not built, and the table below marks them as coming rather than as included. The calculation itself runs in your browser and costs us a page load, so it stays free and needs no account.

What stays free, permanently

The whole designer for batteries and capacitor banks, the cell library, every explanation, and a watermarked export. Charging for the arithmetic would be charging for the step before the one worth paying for.

Questions

Do you recommend where to buy cells?

Not currently. Every cell page links to the manufacturer’s datasheet and nothing else. If supplier links are ever added they will be disclosed on the page, and the ranking will still be computed from electrical fit alone — a designer that recommends the cell paying the most commission is worthless, and it would look exactly like one that does not.

Are these designs safe to build?

They are a design aid, not an engineering sign-off. Every result states the assumptions it used so you can check them, marks which figures rest on a typical value rather than a measurement, and always includes the protection the pack needs. Anything that will be charged unattended should be reviewed by somebody qualified.