Where Android battery actually goes
Your radio (Wi-Fi/cellular) is the biggest per-byte energy consumer on the phone, and it operates in high-power states after each transmission, decaying slowly. Every ad download, tracking beacon and telemetry ping is a radio wake-up — often while the screen is off, when each wake costs the most. Hundreds of background requests per hour mean the radio never fully rests.
The second consumer is CPU: decoding banner assets, running video ads and executing ad SDK logic all burn cycles that produce nothing for you.
What a local firewall costs
A local VPN firewall adds a userspace packet filter. Its cost is dominated by matching DNS queries against a rule set — and with an efficient structure this is tiny:
- Radix-Trie matching evaluates each domain in O(k) — sub-0.4 ms, negligible CPU per request.
- Zero wake loop: the engine holds no timers of its own; it sleeps whenever the radio sleeps. NULLOG's design explicitly avoids periodic CPU wake-ups when the screen is off.
- Memory footprint under 32 MB — a rounding error on any modern device.
- Measured overhead: under 1% daily battery — dwarfed by what the blocked ads themselves would have consumed.
The comparison nobody shows you
| Component | Battery effect |
|---|---|
| Video ad preloading + playback (blocked) | High — radio + CPU + GPU |
| Background telemetry wake-ups (blocked) | Medium — repeated radio wakes |
| Local firewall packet matching | Under 1% / day |
| Remote cloud VPN tunnel | High — constant encryption + remote hop |
Note the last row: the expensive architecture is not local filtering, it is remote cloud VPNs, which encrypt every byte twice and add a server hop. On-device filtering avoids both.
How to verify this on your own phone
- Note battery usage per app in Settings → Battery before installing anything.
- Run NULLOG for three normal days, then compare: you are looking for unchanged total drain and reduced background activity from previously noisy apps.
- Check NULLOG's own entry — it should sit near the bottom of the consumers list.
Put it into practice with NULLOG
NULLOG runs every technique in this guide locally on your Android — ads, trackers and telemetry filtered in device memory. No root. No cloud. No logs.
Download NULLOG APK (v1.0.2)