Overview
The Kaisi Battery Charger is one of our favorite tools and we think it's an essential tool for all repair stores. It's great because it's an inexpensive tool at less than $30 that can do a wide range of things that benefit repair stores. It has 6 connectors so it can work with iPhone 4 through iPhone 6s & 6s plus batteries and with the proper cables you can also use it with iPad batteries.
Activating Dormant/Sleeping Batteries
The first thing we'll address is it's ability to activate dormant or sleeping batteries. Lithium Ion batteries in cell phones have protection circuits that are triggered when the battery goes below a preset voltage which is usually between 2.2 to 3 volts depending on the battery manufacturer. This means that if the protection circuit is triggered at 3 volts then if the battery sits for too long or is drained below 3 volts the battery voltage at the connector will read zero volts. Most phones won't recognize or charge a battery once the protection circuit has been triggered so the battery needs to be activated or boosted using a slow charge to raise the voltage above 3 volts in this example. The Kaisi will activate these batteries when you push the Battery Activation button which can bring back to life what was thought to be a dead or bad battery.
Charging Batteries
Another feature is the ability to simply charge batteries so if you have an iPhone that has a low battery you can charge the battery while repairing the phone. Customers are always happier when they get their phone back and the battery isn't dead or has a good charge so they can test it or are able to use it immediately after the repair. The Kaisi has the capability to charge 2 batteries at the same time by connecting one to the connectors on the left side of the board and then using the connectors on the right side to charge a second battery.
USB Ammeter
The Kaisi unit also functions as a USB Ammeter which can be useful for several purposes. Many stores have a porta-pow or some other USB Ammeter, the Kaisi will do some of the same things. USB Ammeters will measure how many amps are going through it and the voltage. These can be used to test data cables, charging blocks and identify charging/power issues with devices. We'll talk about charging issues first. A common problem with iPhone 5 and later devices is fake charging, intermittent charging or not charging at all. Many stores start by replacing the charge port flex or battery and it might appear to fix the issue. It's important to know if the device is pulling the correct number of amps when it's charging though and the Kaisi unit or another USB ammeter will show you how many amps the device is drawing if any. If the amps are fluctuating or at zero you can be sure you have a charging issue which frequently points to being a tristar issue although there can be other causes. To use this effectively it's important to know what the amp draw for a working phone of the same model so you can compare the readings and know whether it's normal or not.
A couple other things can determine how many amps are displayed on the Kaisi though. The first is the charger or charging block that is being used to power the Kaisi. Different chargers and blocks are rated with different amps, ones that were designed for older model phones might be .5 amps or less. Others that are designed to work with iPads might be 2 amps so the charger or charging block is going to determine the maximum number of amps available which can affect how fast a phone will charge. Newer phones can typically charge faster since they can handle more amps than older phones. If you want to charge your phone faster it's good to make sure the charger/block you are using provides as many amps as your device can support. The other factor that affects the amps is the data cable that connects the charge block and USB Ammeter. Some data cables due to the wiring handle a smaller number of amps than other cables. Be sure when comparing amps across devices you are using the same or comparable cables and charging blocks. As a whole the Kaisi is a flexible and useful tool for repair stores. At times it may be beneficial to have a dedicated USB Ammeter as in some comparisons we've found our PortaPow USB Ammeter to be more accurate. If you're checking for any current draw or wondering if current is fluctuating the Kaisi unit can do this for you.
Summary
The Kaisi unit is available from several sources for under $30 and we think it's a valuable tool for any repair store. We do cover the Kaisi in both our Fundamentals Training course for new technicians and also use it and other USB Ammeters in our Micro Soldering & Board Repair course. We also use it regularly for our board level repairs and troubleshooting we do daily at Device Pro Solutions. Feel free to reach out to us if you have any questions or needs at contact@deviceprosolutions.com