Advanced algorithms and hardware for intelligent batteries

New portable equipment tends to use rechargeable (secondary) batteries because they are cost-effective over the lifetime of the product. Manufacturers who use rechargeable batteries also need advanced electronics to accurately predict a battery´s fuel capacity and quickly recharge the battery. All of this capability is needed in a compact, cost-effective package. National Semiconductor is introducing packaged solutions that meet a user´s needs. This paper discusses the problem and shows how a joint hardware and firmware package solves a wide range a users needs. Portable notebook computers are a significant portion of the market size where a National solution fits. The computer market uses numerous batteries (usually eight to ten in each computer battery pack) and users often buy an extra pack or two because they don´t want to be caught short-charged. Every mobile computer´s power management circuitry needs accurate charging and discharging algorithms. National´s solution provides advanced algorithms that utilize NeuFuz (technology in standard product availability). This technique uses Ni-Cd (nickel-cadmium) and Ni-MH (nickel-metal-hydride) battery packs as its test vehicle. These chemistries represent challenges for state-of-charge determination, due to their discharge profile being nearly flat. It is equally difficult to terminate fast charging because relatively rapid temperature and voltage changes occur suddenly. National´s method monitors several crucial battery parameters: cell temperature, pack voltage and current flowing into or out of the battery pack