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Battery Pack Balancing – The Key to Maintain Top Hybrid and Electric Car Performance

By • Aug 28th, 2009 • Category: Battery Technology for Hybrid and Electric Cars, Clean Car Talk Daily Snapshots

As the automobile industry moves toward alternative energy vehicles, near-term solutions include the already popular hybrid cars and the upcoming electric cars. Ironically, the single common performance killer among these new breeds of cars turns out to be their energy storage or battery packs that help them achieve their high mileage. Batteries tend to be unreliable and greatly affect the performance of any hybrid or electric car. Reliability of hybrid or electric cars can be improved with proper battery pack balancing.

Why is Battery Pack Balancing Needed?

Battery pack balancing is the maintenance of each battery cell, which centers on preventing the cells from reaching the minimum and maximum limits with every full charge and discharge cycle. Balancing the battery pack’s SOC, or state of charge, and making sure that the battery stays at an optimal level between full charge and full depletion can help your battery stay in great condition and can considerably lengthen the life of a single battery pack.

The full depletion of a battery pack is not advised since the extreme ends of a battery’s charge can sometimes cause changes to the electrode surfaces of the batteries. This sometimes happen due to SOC deposits that affect the original composition of the batteries. This may then lead to battery problems and possibly cell damage. To keep the battery pack balanced, the recommended operation is in the mid 30% to 50% of the SOC.

The Challenge of Battery Pack Balancing

Battery pack balancing is not a straightforward exercise. One of the most commonly advised practices is to charge each battery cell individually using separate low-voltage chargers instead of charging them together using a high-voltage charger. This will help prevent imbalance, though it could be a bit taxing and time-consuming to have to use multiple chargers. It is also advisable to shuffle the charges from high to low SOC, though this would require complex circuits and may be faced with certain limitations.

Battery pack designers also recommend the use of shunt clamps while charging. By shunting the current from one battery to the next each time a battery pack reaches the necessary clamp voltage, every battery will remain in the same maximum starting voltage. Aside from that, the use of a passive network may also be helpful. A passive network is an affordable and a manageable way of equalizing the voltage, but make sure to avoid deep discharges as this may affect the life span of the battery pack.

Battery Pack Monitoring

In order to ensure that the battery pack is optimally balanced, monitoring the pack closely is critical. Failing batteries should be identified and replaced when necessary. If a failing battery is not determined in a timely manner and left to continue to function within the pack, it can weaken the battery and its pack, and adversely affect the performance of your hybrid or electric car.

Battery pack monitoring is thus a significant function for proper battery pack balancing. Read more on “Design Considerations for Keeping Your Battery Pack in Top Performance: Balancing and Equalization vs. Pack Monitoring.”

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is a marketing communications consultant working in the San Diego area. Cuong is dedicated to helping individuals and companies maximize their presence on the Internet and efficiently take products and services to market through SEO and network marketing. Cuong also maintains a blog on Marketing at You can also find Cuong Huynh's profile on LinkedIn. For fun he maintains a blog on Vietnamese pho, soccer and do storyboards for movie and film projects. Follow Cuong on Twitter @CuongHuynh, @LovingPho, @CleanCarTalk, @BlockbusterFilm, @SoccerUSA.
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2 Responses »

  1. Hi

    I really enjoy some of your stories and your website in particular.

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