The Chargie app
The app turns the Chargie USB switch on or off, depending on the state of charge reported by the Android smartphone, following a hysteresis charge/discharge curve.
The Chargie USB device
The device acts as a Bluetooth-controlled switch for your charging sessions. That is because your phone manufacturer did not provide you with a way of turning charging off before 100%. It is possible to do it just with software, but only if you get low-level access to the Android system, which is very hard to do and not for all phone types.
On the other hand, Chargie works for all stock phones, out of the box.
How to set it up
Install the hardware
The hardware setup is so simple it’s almost magic.
2. Download the Chargie app from Google Play
You can download the Chargie app right from the standard Google Play on your phone by searching “Chargie”, or the link below:
The app will ask for the following permissions:
- Bluetooth – needed for telling the hardware switch when to shut off.
- Location Access – needed by Google to scan for BLE (Bluetooth Low Energy) devices.
IMPORTANT PRIVACY NOTICE
The Chargie app does not use Location Services for its own inner workings other than for scanning BLE devices. As you may have noticed, it does not have internet access and does not transmit or store your location.
3. Let it run in the background
The Chargie app and the Chargie USB device only work together. It is the app who turns the switch on or off, and the one providing feedback when the battery reaches the desired level.
If you kill the app, the Chargie USB device will act just like a regular power cable, because it won’t have feedback from the app anymore.
The system has been designed like this from the very beginning, to avoid your phone getting discharged should anything happen to the app.
The Android system can kill the app or put it to sleep at its own will for various unknown reasons. This happens rarely, but we considered it’s more important to have your phone charged in the morning, even if to 100%, than not having it charged at all.
3.A. Power saving settings
You should disable any power saving schemes your phone may apply to the Chargie app. The app needs to be permanently active and must not be put to sleep by Android or by 3rd party software or manufacturer firmware.
We will make a comprehensive guide on how to do that for each major phone type. However, as a rule of thumb, you can deactivate power saving on a specific app by holding its icon and accessing “App info” (Android 9 and 10) and then Battery Optimizations.
Update: apparently such a guide already exists. Go to https://dontkillmyapp.com and look for your phone type.
Please try these settings with your phone and see what works for you.
4. Connect to one of your Chargies
When you start the app, it will scan for Bluetooth devices. Make sure you’ve accepted any dialogs when the app starts, as they grant the necessary rights for system to work properly. Take special care of Location Access – it needs to be on, so your Android device can scan other Bluetooth Low Energy devices (Google requirement, your location will not be used by the Chargie app).
Then, just tap on the Chargie you want to use, wait for the Bluetooth icon to turn green and and pass on to the next step.
If you have more than one Chargie device in the list, a down-pointing animated arrow will appear below them. Just swipe down or click that arrow to see the whole list. If not used, it will collapse to just one item after 10 seconds, to save screen space.
After the charge-mode Chargie is set, the app will automatically connect to it when the phone is plugged in next time. If you own multiple Chargies and the next time you use another one, you have to manually select it again. After that, it will default to the last one used.
5. Set your desired charge limit (%)
After you’ve connected the app to the Chargie USB device, drag the battery-shaped slider to your wish. You will notice that if the current charge percentage is higher than what you set, the red LED on Chargie will turn off, and so will power to your phone.
5.1. Allowed Discharge
Chargie lets your battery fill up to the percentage you choose, waits for it to drop a certain amount and then restarts charging.
The allowed percentage drop is defined in Settings -> Allowed Discharge.
You can charge up to whatever value you wish, and it’s best if you charge somewhere between 80 and 90%, depending on your daily needs.
There are days when you know you’ll need a full battery. Just set the threshold to 100% and Chargie will still do a better job than if you hadn’t used it, by going to 100% and then performing a hysteretic charge. What that means is it lets the phone discharge the Allowed Discharge amount and then recharges again.
The discharge normally happens very slowly during the night, since it’s being done with the screen off. This lets the battery cool down to room temperature and doesn’t add stress to it, like a normal charger would by constantly topping it up to 100%.
All of this should keep the battery happy and less stressed than normal charging, which surely guarantees a longer lifespan and a more satisfying overall user experience.
6. How to delete a Chargie from your list
Tap the three vertical dots in the top right side of the screen -> Manage Devices.
Click on the red X circle to delete any of the Chargies you connected to in the past. Their name will go back to “chargie”, and you’ll be able to change it whenever you connect to them again.
7. Customize your Chargie's name
By default, renaming a Chargie just associates a certain MAC address (the hexadecimal numbers you see below the name) with a name chosen by you. Other phones will see your Chargie named as “chargie”.
If you want your customization to become permanent (until you decide to change it again, of course), activate this option in Menu – Settings:
This option will allow for permanent renaming even if you don’t check the “write to device” option when the actual rename dialog pops up. It will also deactivate “Show only Chargie devices”.
8. What the icons mean
The icons are very important to understanding Chargie’s state very quickly. They’ve been designed to be intuitive, but just to keep things safe, their meaning is written below.
All of their grey variants show the inactive status. Red bulb means Lamp Mode is active but switched on.
a. Charge Limiting mode
This is the default mode that the Chargie app is in when you start it. It offers feedback to the Chargie device according to the phone’s state of charge.
b. USB Switch mode
By turning on this mode, your Chargie will act as a simple on/off switch for USB devices. You’ll be able to remotely control any type of USB-A device from the Chargie app and invent all sorts of use cases where Chargie saves the day.
Red means “off”, yellow means “on”. Grey means the mode is not active.
c. Top up scheduler
This mode, once enabled, allows you to turn your Chargie device into a scheduled on/off switch.
It gives you the unprecedented power of keeping your state of charge at a safe 50 to 70% during the night (or while you’re at work) and only top up to whatever high charge value you’re comfortable with shortly before leaving home or your workplace.
This is highly beneficial for both the battery and the usability of your phone, since it’s not always possible to make it through the day with an 80% SoC (State of Charge) so that you keep your phone safe from prolonged elevated voltage.
- the main one that you set by dragging the battery slider.
- the “Top up level,” whose start will get triggered at the time that you set. Please do not confuse the two, as #1 will execute first. Only after it reaches the basic charge limit, the app will launch #2 within an hour from the time you set in the dialog.
d. Android Auto Mode
* only available on Chargie A devices. Chargie Founder Edition does not have this function.
This mode will allow you to use Android Auto or similar interfaces while not keeping the state of charge at 100%.
It works by employing a second low power switch that only lets pass a small current through your Chargie, so the car’s USB system thinks it’s still connected to the phone, but in reality the phone is discharging (net power consumption is positive).
The aim of this mode is to keep the USB data connection active while the phone is not charging.
You have to keep the Chargie app open for Android Auto mode to work.
Some phones, like the Pixel 3a (tested in our lab) don’t allow power to be resumed from a partial charging state (such as the one induced by the Android Auto mode). In that case, you need to go to Settings – Android Auto and enable “Blip power before charging”. This is the only workaround we could find, since the phones probably have this hardwired.
From our experience, we’ve tested Android Auto mode on a Xiaomi and a OnePlus 7T and they didn’t exhibit the abnormal behavior, so no blipping was necessary.
Shortly cutting off power completely before resuming it may interrupt Android Auto but it should restore connection immediately.
As there are a multitude of configuration possibilities for this mode, we DO NOT GUARANTEE that your Android Auto device will work with Chargie well. You are using this function at your own discretion and risk, as it is merely a workaround and not a scientifically-sound way of data transmission while the phone is not actively charged. But it does the trick for most phones we’ve tested.
e. Hardware power limiter
* only available on Chargie A devices. Chargie Founder Edition does not have this function.
There are some phones that can’t run the Chargie app, and there are people who would rather shut off their device when charging at night.
The Hardware Power Limiter function lets you set a power threshold (in Watts). This value will be sent to the Chargie A and newer device and stored into its non-volatile memory. *
When charging, the Chargie device constantly monitors power and, if it goes south of the threshold you set for more than 30 seconds, it stops the charging process.
It then waits for a configurable amount of time (you can set it in the Hardware Limiter menu) and briefly rechecks power until the power threshold condition (+1W) is met. You should configure this to a value you estimate as fit for your application.
The Hardware Limiter is a very powerful and useful function for all kinds of devices that can’t run Chargie, like lithium ion batteries, various devices like mobile projectors or even old phones.
While you may find it easy to use in some cases, if you set the recheck timeout very high, the phone will charge to the maximum after a few days, since the net power uptake will be higher than what the device actually consumes between the power checks. But this is generally not the case for one-night charging. We designed default values to work very well in 99.9% of the use cases.
In the beginning, people would order only one Chargie to test it. Then, word spread out and most customers now want a Double or Family Pack, to protect all of their phone batteries.
That is why we have implemented an Autoconnect feature that allows you to switch the Chargie you’re using with another one, seamlessly.
This function doesn’t have its own menu it is activated by default.
Using it is simple: just pair the app with all of the Chargies you own. It will remember them and the next time it will connect to the last one you used.
However, if it’s not the same every time, the app will go through all of them and try to put the line down for a split second. When it detects the power change, it means it’s physically paired with the correct Chargie and will take control of it via Bluetooth.
Attention: do not rely entirely on the Autoconnect feature, especially when you have little experience using your Chargie. Due to interference or low Bluetooth signal between the physical Chargie device and your phone/tablet, Autoconnect may not manage to do its task properly and will require manual reconnection.