🔵 미니 충전 드라이버 리튬배터리로 교체하기 (스위스밀리터리 4.8v)

#lithiumbattery #minirechargeablescrewdriver #nickelcadmium #swissmilitary I replaced the nickel-cadmium battery in my mini rechargeable screwdriver with a lithium battery. The original nickel-cadmium battery was 4.8V, and the replacement lithium battery has a full charge voltage of 4.2V. I'll briefly explain why this is acceptable. NiCd (nickel-cadmium) batteries and lithium batteries are virtually identical, as shown in the discharge efficiency graph. However, lithium batteries have a higher energy density, allowing them to store significantly more energy than nickel-cadmium batteries, resulting in a larger capacity. The nickel-cadmium batteries used in the screwdriver are four 1.2V, 600mAh batteries connected in series, for a total of 4.8V, 600mAh. The replacement lithium battery has a nominal voltage of 3.7V, 2000mAh, and a full charge voltage of 4.2V. A simple comparison of the batteries reveals that the NiCd battery has an output of 2.88 Wh (4.8 V x 0.6 A), while the lithium battery has an output of 7.4 Wh (3.7 V x 2 A). When both batteries are fully charged, the lithium battery has an output of 4.2 V and the NiCd battery has an output of 1.4 V to 1.45 V, resulting in a maximum output of 5.6 V to 5.8 V for four batteries in series. During initial operation, the higher voltage of the NiCd battery allows for faster motor RPMs and greater torque for a short time. However, under load, the capacity decreases rapidly, the voltage drops, and the torque quickly weakens. Lithium batteries have a lower voltage than NiCd, so the RPM is slower during initial operation. However, because lithium batteries have several times the capacity of NiCd, they can be used for longer periods without losing speed and torque. (In practice, using lithium batteries actually improves the driver's power.) Lithium batteries are also lighter than NiCd batteries. The natural discharge rate also varies significantly. For example, NiCd batteries, when stored after being charged, are often discharged and require recharging when ready to use. For reference, lithium batteries have an initial natural discharge of about 5% upon completion of the initial charge, and then a natural discharge of 1-2% per month thereafter. There are virtually no disadvantages to replacing lithium batteries. The only drawback is the temperature range. According to LG Energy Solution, the safe charging temperature range for lithium is 0 to 50°C, the operating temperature range. NiCd batteries have a slightly wider temperature range, -20 to 45°C. However, under normal conditions, there's no reason to use NiCd. So, while NiCd batteries were once widely used for military purposes, they're increasingly being replaced by lithium batteries. Thank you for watching.