One example of the battery management challenges associated with a higher power application is a battery powered string trimmer. The electric motor, which puts the load on the battery, is in the tool head near the ground. To give better weight distribution, the battery pack is typically near the handle. This means there are several feet of cable between the power source and the load. When the motor is running, it could be drawing 10, 20, or even 50A for short bursts, and even higher under stall conditions. So when the motor kicks on and off, there can be very high voltage spikes, as there is some inductance due to the long cable, and very fast current transients with a high power motor. Thus, there are high voltage spikes on the battery terminals and the battery management circuit needs to handle this. Additionally, for many power tool applications, the discharge currents can be very high. Most tools are used for only a few seconds or minutes, with rest periods in between. So, the power transistors used in the battery protection circuit need to handle up to 100A or more. However, these packs are typically charged at only a few amps. If the traditional series FETs are used, then both FETs must be rated for 100A even though the charge FET only needs to pass a few amps. This of course will affect the cost of the components used. To save this cost, many designs actually use separate contacts for charging and discharging the battery pack. The charging path uses lower current power switches to save in the overall BOM cost of the system.