crop_vbat.awk

stream discharging battery data crop utility

Rev.1.01 (2026-02-17)

Takayuki HOSODA

crop_vbat.awk reads numeric voltage samples from standard input or files and extracts (crops) discharge segments based on monotonic voltage behavior. It is designed as a UNIX-style stream filter that can be composed with small tools.

Synopsis

crop_vbat.awk
  [-v v_start=V]
  [-v v_term=V]
  [-v v_delta=V]
  [-v v_abn=V]
  [-v cont=N]
  [-v myname=NAME]
  [FILE ...]

Description

Input must contain one numeric value per line. Non-numeric lines are rejected and reported to stderr. All computations are done numerically, but output preserves the original text format.

Start and termination of a discharge segment are detected using either delta-based or absolute threshold criteria. Multiple segments can be extracted from one stream when continuation mode is enabled.

Input format

One numeric sample per line
Optional sign, decimal, and scientific notation supported
Trailing CR characters are removed automatically
Original numeric formatting is preserved on output

Accepted examples:

+01.234
0.98
3.01E+00
.75
2.

Decimal point must be '.' (no locale conversion).

Segment detection

Start condition (output enabled):

If v_start not specified: current < previous - v_delta
If v_start specified: current < v_start

Termination condition (output disabled):

If v_term not specified: current - previous > v_delta
If v_term specified: current < v_term

Options

All options are given via awk -v variables.

v_start=V — absolute start threshold voltage
v_term=V — absolute termination threshold voltage
v_delta=V — delta threshold (default 0.02 V)
v_abn=V — over-range rejection threshold (default 10.0 V)
cont=N — number of segments to output (1 … 2⁵³ - 1, default 1)
myname=NAME — stderr log prefix label

Integers are exact up to 2⁵³ - 1.

Output

Cropped samples are written to stdout unchanged. Diagnostic messages are written to stderr with the program label prefix.

Exit status

0 — normal completion
1 — argument validation error

EXAMPLES

Extract a voltage column and crop one discharge segment:

cut -f 4 data.tsv | crop_vbat.awk

Use explicit thresholds:

crop_vbat.awk -v v_start=1.25 -v v_term=0.95 log.txt

Allow three discharge segments:

crop_vbat.awk -v cont=3 log.txt

Capacity estimate with fixed interval and load:

cut -f 4 sample1.dat \
| crop_vbat.awk \
| stats.awk -v out=tsv \
| grep sum \
| awk -v r=2.5 -v dt=10 '{print $2 * dt / r / 3600 * 1000}'

Download

Download crop_vbat.awk-1.01.tar.gz — SPDX-License-Identifier: BSD-3-Clause

Hash values

Archive contains SHA256 and MD5 hash files.

SHA256 (crop_vbat.awk) = 25c3aa6c3ff62ad085f3c4cf19bfea486810f7fe6faec62a0429ccb402bd9a7f
MD5 (crop_vbat.awk) = 83c3400f7ca388c1e81f7745bec8cfab

Users can verify the distributed crop_vbat.awk using:

sha256 crop_vbat.awk
md5    crop_vbat.awk