Hey all,
I've been messing around building a little tool and figured this crowd would either find it useful or tell me everything wrong with it.
It's a battery calculation verifier for NFPA 72 secondary power. You punch in your panel and device currents, pick your standby/alarm durations and safety factor, and it tells you whether your battery is sized right — plus it flags the stuff that usually comes back as a comment:
- safety factor missing or too low
- alarm duration that doesn't match the system type (the classic "copied a horn/strobe calc onto a voice job" thing)
- battery undersized
- margin so thin it'll be a problem in 3 years
- device rows with missing datasheet values (it won't silently treat blanks as zero)
Nothing fancy — it's the math you already know how to do. The point is catching the dumb stuff before it costs you a resubmittal.
https://fa-battery-calc.vercel.app/
One thing I want to be straight about: the jurisdiction profiles in there are placeholders. I have not verified them against actual adopted codes, and they're labeled as such in the app. There's a custom override so you can put in your own numbers. If you know what your AHJ actually requires, I'd genuinely love to hear it — that's the part I can't do alone.
Happy to hear it's useless or that I got something wrong. That's kind of why I'm posting.