Hello everyone, welcome to the ZimZimdIY channel. Have you ever wondered why the lithium batteries we use in most electronic devices have such a short lifespan? For example, a cheap solar cell lamp that can only be used for 2-3 months can't hold a charge very well, unlike the first few days when you first bought it, which was bright until morning. Sometimes I secretly wonder if they put a battery or a capacitor inside. Many of you might say, "Well, Mr. Sim, you bought something cheap, so they put a poor quality battery in it. It broke after a short time." Yes, there are quite a few factors involved, but usage behavior can speed up the deterioration of the battery by 10 or 20 times. Today, let's analyze and find the answer together with Brother Bear and the ZimzimDiy channel as usual. Let's see what causes it. For example, let's say I bought an LFP battery and the factory specified that it has a cycle or lifespan of 2,000 cycles. 2,000 cycles if charged and used once a day, that's more than 5 years. But there is a condition that the DoD must be at 80%. What is a DOD of 80%? DoD is an abbreviation for Depth Of Discharge. Delp means depth. Discharge means discharge. Translated together, it means the depth of discharge. Therefore, if the battery is discharged no more than 80%, it can be used for up to 2,000 cycles. The lower the DoD percentage, the longer the battery will last. Note that this battery says that a DoD of 65% can be used up to 5,000 cycles, and a DoD of 40% can be used up to 8,000 cycles. The question is, how do we know that our battery has discharged to 80%? In fact, we can look at The capacity of the battery that we bought and used. For example, let's say this LFP 32650 battery has a capacity of around 5,000mAh, we multiply 5,000 by 80% to get the capacity of 4000mAh. Simply put, we should use 4,000 mA and store the remaining 1,000mAh in the battery. This way, the battery will definitely last a long time. Now, our big problem is that we don't know when the battery will discharge to 4,000mAh. To be sure, we need to use a device to measure the capacity, which is not easy. And if we look at the Volte, the Volte of the LFP battery is... not related to the capacity value. Do you know? The voltage range of LFP batteries from 3.2v to 3.4v has a possibility that the battery may have a capacity between 20% - 80%. Therefore, we cannot predict the voltage from the LFP battery. This is a big problem that circuit designers often have a headache with regularly. Now, we have to guess. Let's set the voltage lower than 3.2V, the battery is considered to be less than 20% of its capacity. Therefore, if you want your battery to last a long time, one option that will be presented is to try not to let the voltage fall below 3.2V. But in reality, what happens? We use electricity until the BMS cuts off, right? And the question is, at what voltage does the BMS cut off? Most are around 2.75V, 2.5V. Some models are 2.35V. If it is a 1s BMS, it is 2.2V. So the question is, at a voltage that low, does the Dod exceed 80%? Yes, it may even go to 90% or 95%. And if you use it like that every day, repeatedly, the battery will deteriorate faster. The IR value will increase and the capacity will decrease. When the capacity is reduced, the battery starts to store less power. Store less electricity, causing the charging cycle to decrease from 5 years to only 5 months. Some people have 3 months, less than 1 year. But in this bad luck, there is still some good luck. That is, if the BMS cuts off, you have to quickly charge the electricity back in. When the BMS cuts off, it charges immediately. This is even better. The battery will not be damaged much. Because if the LFP battery is left at a very low capacity for many days without charging it back in, it may cause the battery to deteriorate permanently. Therefore, the life cycle of the LiFePO4 battery, whether short or long, the Dod value is quite a big factor. For today, Brother Bear and I have given all the information to our friends. Thank you to all our friends who have been following and watching.