Traction batteries for EV and HEV Applications
Typical battery requirements apply traction Traction applications have traditionally been working for lead acid batteries, but the restrictions lead acid batteries, including the high cost alternative, which in turn limits the range of potential uses battery powered traction. A typical family car would have the battery capacity of about 40 kWh to provide one way to the 200 miles and 40 kWh of Lead Acid batteries weighs 1.5 tons.

The situation changes, however, the new battery chemistries and supporting technologies have created new technical solutions and economic benefits of making the battery pay for traction applications that were previously unprofitable and unrealistic. In particular, the use of lightweight nickel metal hydride and lithium batteries instead of the heavy and bulky lead acid batteries has a practical electric vehicles and hybrid electric vehicles, the possibility for the first time.

General requirements:

It is obvious that low cost, long time (more than 1000 cycles), low self discharge rate (less than 5% per month) and low maintenance costs are the basic requirements for all applications. Traction batteries usually operate under very difficult operating conditions and must withstand a wide temperature range (-30 ° C to +65 ° C), as well as shock, vibration and abuse. Low weight is not always a priority to ensure stability of the heavy weight of material handling equipment such as forklifts and handle the necessary aircraft tugs to tow heavy loads. However, low weight is essential to ensure high-capacity EV vehicles and HEV batteries used in passenger vehicles and that excludes the lead to these conclusions.
Circuit protection is also essential to the battery using a non-Lead Acid chemistries.

Purchase Specifications:
Traction batteries are very expensive and, like all batteries they deteriorated during their lifetime. Customers are demanding a minimum level of performance even at the end of battery life, so the buyer can specify the results expected by the end of life (EOL), and not the beginning of life (BOL). Under normal circumstances, applications for GE's ability EOL is defined as no less than 80% of the capacity of BOL. HEV applications for changes in the internal impedance is often used as an indicator of age. In this case EOL internal impedance can be defined as no more than 200% of BOL's internal impedance.
12 Volt Automotive SLI (starting, lighting and ignition) Battery Operating Requirements One deep discharge a short time (50% depth of discharge (DOD) with at least 5C rate), and then trickle charging. The battery is essentially always fully charged. No prolonged collaboration with the deep discharge. Typical capacity 0.4 - 1.2 kWh (33 Ah - 100Ah.) Maximum power 2.4 -3.6 kW (200 - 300 amperes).
PowerNet 36/42 Volt Battery Operating Requirements One of the deep discharge followed by intermittent heavy loads of electricity. No prolonged collaboration with the deep discharge. High efficiency and high cycle life necessary, especially if you stop / start functions used to run support. Tolerant to repeated high current pulses.are n Typical capacity of over 1 kWh. Peak power 5 to12 kW.
EV, HEV and PHV Battery Specifications The graph shows a comparison of the battery and the capacity requirements for a vehicle of the same size and weight, as EV, HEV or a PHEV configuration. Models of batteries can be optimized for power or capacity (energy content), but not both (see the energy trade-offs in the section Cell Construction), and therefore the type of cells used, and not just quantity, must be selected for use.
In the case of EV, the battery is the only source of power, and so the battery must be selected to achieve this power more or less continuously. EV capacity must be sufficient to achieve the required range, but also because it is not desirable to fully discharge the battery, a margin of about 20% is required to discharge depth shall not exceed 80%. Further margin of around 5% is also required to take regenerative braking charges a battery has just been charged. In othe words the battery should be directed to ensure the required capacity at the maximum SOC is 95% and up to 80% DOD. Continuous discharge rate of batteries are optimized for efficiency is typically about 1C, although some cells can tolerate pulsed currents to 3C or more for short periods. EV battery deep discharge usually one day from an intermediate topping the regen braking and the typical life of lithium-EV can be from 500 to 2000 cycles.

Corresponds to a series of hybrid batteries must also be able to provide the same power as the battery EV, because these vehicles are essentially the same size and weight, and intermittent periods of battery will be the only source of energy. However, due to global demand for energy is made available in an internal combustion engine (ICE) of the required battery capacity is much smaller. Parallel hybrids can have different arrangements for the sharing of power and so their energy requirements may be addressed by less battery power. HEVs, therefore an additional burden and complexity of the exercise about two power sources, each of which is large enough to power the vehicle on its own.
As a result, severe restrictions on the formula weight and size of the battery, which can be taken into account and HEV batteries are typically less than one-tenth the size of EV batteries used in the same vehicle size. Unavoidable consequence is that in order to obtain the same power of a battery one tenth the size of the HEV batteries must be able to supply current to 10C and more. Fortunately, the power is disconnected (but much longer than the required short pulse), because it is shared with ICE. Battery capacity is therefore less important than the supply of energy in hybrid vehicle, because the scope can be extended by a motor. Therefore, HEV batteries optimized for power.
The downside is that because of its low capacity of the HEV battery is constantly charged and discharged during normal operation and may be subject to the equivalent of one hundred per-discharge cycles per day. With deep discharge of the battery is, unfortunately, to be consumed within a few weeks. But we know that the life cycle of batteries is increasing exponentially in the DOD is limited (see the cycle of life and the DOD in the section on battery life) so that the HEV batteries must be carried out at partial DOD to extend the life cycle. This means that the battery capacity must be increased to allow for lower Dods although full capacity is almost never used. In this example, the HEV battery operates from 40% to 80% SOC. Longer working time can be achieved with even higher capacity batteries so that the desired capacity can be transported between the SOC ranged from 60% to 75%.

Plug in hybrids must work part time in EV mode, the depletion charge and part time in maintenance mode HEV fees. See detailed PHEV requirements below. PHEV battery requirements to be a compromise between energy storage and energy supply.
This is a major challenge for producers of the cells.