Hello everyone, welcome to the ZimZimDIY channel. For the previous clip, I made a clip explaining to my friends that connecting parallel batteries in balance is useless. Even though the voltage flows the same, the capacity value will hardly change at all. As for the best method that I recommend, it is to charge each battery to its full capacity and then assemble it into a pack. At least we can be sure that our batteries have the same full capacity. But now, there will be a question. If there are only a few batteries, 3-4, it's okay, no problem, we can still charge them separately. But if there are a lot of batteries, 30, 40, sitting and charging them leisurely, enjoying the view, one by one like this, it's not possible, right? For this clip, I will introduce a method for charging a large number of LFP batteries using only one charger. There are about 2-3 main techniques, which are guaranteed to be safe and truly usable. Let's look at the first point. 1. Let's try to select each battery. Keep the voltage at about 3.2V or higher. If the voltage is lower than this, it is recommended to charge it to that voltage first. And it is recommended to charge with a low current of about 0.5A. Many people may wonder why use such a low current? Because at a voltage lower than 3.2V, the battery will have very little energy left or almost depleted. If we charge with high current now, it may cause heat to build up and adversely affect the life of the battery cells in the future. 2. Connect the batteries in parallel. It is recommended to connect a maximum of 20 batteries in parallel. 3. Use any charger that can control the voltage and charging current. If it is a Powersply, choose one with the CC or Constant Current symbol. If it is a BuckConverter, choose one that can adjust the charging current. But if you have a Smart Charger, that's even better. 4. Charge with a current not exceeding twice the capacity of a single battery. The more batteries there are, the longer it will take to charge. That's why I recommend connecting no more than 20 batteries in parallel because it will take too long to charge. So how do you know when the batteries are full? If the battery is full, the voltage will touch 3.65V and the current will be less than (0.05C x total capacity), which means the battery is full. Suppose there are 5 batteries in parallel, the total capacity is 25Ah. 25Ah x 0.05C = 1.25 If the current is less than 1.25A, it means that the battery set is full. That's it. It is considered a simple method but gives very good results. However, in some cases, they use a switching power supply that cannot adjust the current. The output current is freestyle 30-40A. If it is charged, what will happen? It turns out that one of the batteries explodes. Boom... the cores burst out. Initial Cause At the scene, we assume that one of the battery cells has a lower capacity than the others or that the battery cell is deteriorated and has a problem. That is, if you find a battery like this, these batteries tend to have lower voltage than their friends and tend to consume more current than the other batteries in order to catch up. Especially if the other batteries are saturated with current, they don't need current, right? All the current will flow to charge the problematic battery, only one battery, causing extreme heat until it explodes. But if our charger sets the charging current not to exceed 2 times the capacity of 1 battery, even if the total current is 2 times, it will take it by itself, about 2C. At least, it may be just warm and hot, which is enough for us to observe the symptoms and guess the symptoms because LFP batteries are known for their durability. If it does not exceed the actual cause, the chance of it exploding is very low. This is why me and Brother Bear repeatedly emphasize that the charging current of the charger is an important matter that we should not overlook. For this clip, I will explain this much first. Thank you to all friends who have followed and watched.