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Understanding Lithium Ion Capabilities and Limitations


Capabilities:

1. Lithium Ion Chemistry in Batteries haves high energy density. The energy density of lithium-ion is typically twice that of the standard nickel-cadmium. There is potential for higher energy densities.

2. Better weight to energy density ratio. A typical lithium-ion battery can store 140 watt-hours of electricity per Kg weight of battery. A lead-acid battery can store only 30 watt-hours per kilogram.

3. Lithium-ion is low on maintenance battery.

4. There is no more memory effect in present Lithium Ion Batteries.

5. In addition, the self-discharge is less than half compared to nickel-cadmium

Limitations:

1. Due to Chemical reaction Ageing is by default.

2. Capacity deterioration is noticeable after one year, irrespective of usuage.

3. Temperature above 35 degrees C affects Lithium Ion battery pack performance instantly and may become permanent if extended exposure persist may be over two months period.

4. Even performance of lithium-ion batteries decreases in cold weather.

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Lithium Ion Battery pack in xEV

In Electric Vehicle application there are typical occurring of short pulses as per driving, load, breaking and road gradient profile, this means that for the given event occarance, the battery is required to produces power for handling the same, and is also required to maintain energy density for coverage of travel distance. In view this scenario expectatations Lithium Ion Batteries are best Choice in present state of "Energy Storage Technology" availablity, inspite of reffered limitations.

There is lack of information amongst the most of Auto manufacturer regarding the performance of Lithium Ion Batteriesas under different terrian typically that of Indian climatic conditions It is observed that to compensate for loss in capacity in ambient above 35 degree C applications EV manufacturers tend to increase the size of the batteries to allow for take care of degradation within the service life, and operate below available capacity by controlling state of Charge and Discharge through BMS, to do away with extra cost for incorporating collant circulation system for reffered Power-pack

How to Keep Lithium Ion Battery Healthy in xEV

1. Avoid 'deep discharging' of the batteries.

2. Maintain state-of-charge within 50-70 percent of capacity, before leaving it unused for an extended period of time

3. Ensure to at least in every 2 days even if the State of charge is 60%. Please note Lithium-ion batteries tends to last longer when they are charged and discharged more shallowly, rather than charging from 0 to 100 percent.

4. Once a week, keep the battery pack plugged in for overnight charging for atleast about 10 hrs since this enables the Battery Management System (BMS) to attain proper balance of individual cells in reffered Power-pack.

6. Always Keep your xEV in cool sheltered Parking as batteries are sensitive to heat.