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I work for a major repair chain and the company practice is to replace batteries that test over the rating on the battery which is 3.8v calling it a voltage leak however I always believed that 3.8-4.2v was the operating voltage with 4.2v being 100% charged. Batteries are not designed to resist voltage to my knowledge, they are just an open gate unlike a step down transformer. I charged a battery to 100% in the phone and then tested the voltage which read 4.2v however I also have a Kaisi battery activation and charging board. That will charge a battery to 4.33v and then stop, so can anyone confirm this? Thanks
Can you explain this policy a bit more…it seems rather uninformed. A Li-ion battery has a nominal voltage of ~3.7V…that means this is the normal operating voltage. It is hardly a failed battery when it is at 3.8V. A fully charged battery will be ~4.2V. The phone will operate with the battery as low as ~3.1V. Voltage is not the proper way to determine if the battery needs replacement or not. The proper way to do it is to look at the actual design capacity of the battery, via software tools like coconutBattery or 3uTools. There are also some hardware solutions available that do the same thing. You are essentially reading the data off the gas gauge IC inside the battery pack. The challenge nowadays is that most replacement batteries have sketchy readings from the gas gauge. I ordered one batch of batteries from a supplier and noticed they all had the same serial number and design capacity specs…dubious at best. The other option is to physically test the battery against a dummy load. I certainly wouldn’t do this on every battery but it’s a great way of spot checking a supplier or a particularly frustrating repair where you need to be certain the battery is good (despite good data from the gas gauge). This is a good/new battery running at 0.1C. Note how the majority of the time, the battery is operating around 3.7V (hence the nominal rating) and it lasts around 8 hours.
This is a dead/dying battery (23% of design capacity). It also operates around 3.7V but only lasts 48 minutes before hitting the 3V threshold.
You may have noticed the bounce back effect in this second chart. Once the battery hits 3V, the load is cut and you can see the battery voltage bounce back to ~3.8V. The battery is fully depleted yet still shows 3.8V without a load (such as a multimeter).
HI, you will find that the Kaisi board is not a safe way to charge a battey and has no safe way to charge. Please take a look at the below links to get the best answer. https://www.aonemobiles.com.au/2018/06/i… https://www.aonemobiles.com.au/product-c… Please let me know if you need further assistance.
