Prevent Battery Swelling on Unattended Devices
Repurpose old smartphones and tablets for 24/7 smart displays, security cameras, and IoT nodes without the risk of bloated batteries or fire hazards. Online Battery automates your WiFi smart outlet to keep your device strictly within its healthy 40%–70% charge window and safe temperatures.
Why Leaving Smartphones Permanently on AC Power Causes Catastrophic Failure
When an Android device is kept plugged into a standard wall charger 24 hours a day, its lithium-ion cells remain pinned at their maximum cell voltage (~4.35V). Combined with the internal heat generated by CPUs running dashboards or camera feeds, this accelerates electrolyte decomposition, causes gas pouch swelling (pillowing), and drastically increases the risk of thermal runaway and fire.
Battery Swelling & Delamination
Constant high-voltage float charge leads to gas formation that pushes the screen off the chassis and bends the device frame.
Thermal Degradation
Ambient room temperatures plus charger heating cook the device above 35°C–40°C, destroying battery chemistry in just a few months.
The Online Battery Solution
We wirelessly cut AC power at your chosen ceiling (e.g. 70%) and resume only at your floor (e.g. 40%), simulating gentle, healthy battery cycles.
Works Over WiFi with Your Favorite Smart Plugs
No proprietary hubs or cloud middleman required for standard cycling. Online Battery speaks directly with popular smart power outlets over your local network.
TP-Link Tapo
Native protocol integration for popular Tapo plugs (such as P100, P105, P110). Connects directly on your local WiFi using secure session handshake.
- Fast local switching
- No external bridge needed
Shelly Devices
Zero-latency local REST HTTP API control for Shelly Plug, Shelly Plug S, Plus Plug, and Shelly 1PM relays (Gen1, Gen2, and Gen3).
- Local Gen1 / Gen2 HTTP RPC
- Rock-solid reliability
Home Assistant
Have Zigbee, Z-Wave, or Matter smart plugs? Trigger any Home Assistantswitch.*entity seamlessly via Long-Lived Access Tokens.
- Any entity supported by HA
- Local REST API endpoint
Peace of Mind with Cloud Heartbeat & Immediate Thermal Alerts
When running unattended devices in offices, warehouses, or remote locations, you need to know the instant something goes wrong. Subscribe directly through the Google Play Store (managed by RevenueCat) to unlock real-time fleet health checks:
Devices periodically check in. If an app is killed by Android battery optimization or a WiFi router reboots, you are alerted before the battery drains or overcharges.
Receive high-priority email alerts sent via Resend the second device battery temperature breaches your maximum limit (e.g. > 35°C).
Fleet Telemetry Pipeline
Engineered for Unattended Stability
Everything you need to turn spare Android hardware into permanent, maintenance-free equipment.
Customizable Range Thresholds
Define the exact charge boundary for your device. Choose 40% to 70%, 30% to 80%, or any custom window suited for your lithium chemistry.
Active Thermal Cutoff
If ambient sun or intensive tasks push device temperature above your threshold (e.g. 35°C), the plug is immediately shut off regardless of battery percentage.
Local-First Privacy
Your smart outlet IP addresses and passwords are never transmitted to our cloud. All outlet toggles happen over your local WiFi LAN.
Auto-Start on Boot
After an unexpected power outage, Online Battery automatically launches in the background and resumes monitoring without requiring user interaction.
Cloudflare Worker Heartbeat
Lightweight HTTP pings sent at regular intervals verify that the device is running, cycling, and responsive.
Simple RevenueCat Billing
Subscriptions for fleet management are managed securely through your standard Google Play Store account. Cancel anytime with a single tap in Play Store settings.
Common Questions & Architecture
Does Online Battery require root access on the Android device?
No! Traditional battery limters require root access because Android does not provide an API to stop charging while physically connected to power. Online Battery solves this elegantly without root by toggling the external AC power outlet over your local WiFi.
What happens if my WiFi network goes down?
Online Battery is designed with defensive programming. If the app cannot reach the smart outlet to toggle power, it retries with exponential backoff and logs the connection fault. If you are subscribed to Fleet Monitoring, the Cloudflare Worker will flag the missed heartbeat and notify you.
How does the 24-hour GDPR data auto-purge work?
We practice strict data minimization. We only store the device ID and registered alert email necessary to dispatch alerts while an active subscription exists. Exactly 24 hours after your Google Play subscription lapses, a scheduled database job irrevocably erases your device records. You can also request immediate deletion via our Data Deletion form.
Give Your Old Android Devices a Long, Safe Second Life
Stop worrying about battery fire hazards and swollen screens. Download Online Battery and pair your first smart plug in under 3 minutes.