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Published on April 18th, 2013 | by Yellow Magpie


Electric Battery Terms: Electric Batteries Made Simple

Electric Battery Terms: Photo By Claus Ableiter

Electric battery terms are important to comprehend when it comes to choosing the right battery for your needs. This is especially critical when picking the right battery for your electric bike.

There are several different terms, some of which are combined, that can be confusing to people being confronted by these nomenclatures for the first time. Yellow Magpie will take a look at these electric battery terms and demystify them.

Electric Battery Terms: Not As Difficult As You Might Think

Battery terms can be initially quite befuddling. However, once you understand one or two concepts you can quickly learn them in less than five minutes. There are four basic terms that need to be understood. Volts, amps, cycles and the C-rate.

Amps (short for amperes) is the amount of electrical current flowing through an electric circuit for a certain duration of time. In other words, it is the rate at which electricity flows.

Volts is the force at which the current (amps) pass from one place to another. A common analogy used is water pressure.

Watts is the rate at which energy changes from one state into another. In the case of electric bicycles watts are a measurement of the amount of energy that is either stored or used.

The C-rate is the assessment of how long it takes to charge or discharge a battery in one hour.

Combining The Basic Terms

Now that you have these basic concepts down what is left is just a combination of these terms. Electric bicycle batteries commonly are 36 volts  or 48 volts. The higher the voltage the faster the electric bicycle will be and the larger the battery the greater its amp/hours. A 15-amp-hour battery will provide greater range than a 12-amp-hour battery.

 Electric Battery Terms: Lithium Iron Phosphate (LiFePO4) Photo By Rudolf Simon

The total capacity of a battery is measured in watt-hours. To get the watt-hours you simply multiply the volts by the amp-hours. For example, a 36 volt 20 amp-hour battery will provide roughly 800 watt-hours (40 x 20=800).

Electric bicycle batteries will always have a higher nominal voltage than the common number given to them. For instance, a ’36’ volt battery will be close to 40 volts. This is in the same way that the standard ’12’ volt car battery is much closer to 14 volts than 12.

Electric Battery Terms: The Importance Of C-Rate

The C-rate of a battery dictates just how much power it can output and how quickly it can be be charged. A 30-C battery, 1,000 watt-hour battery can provide 30,000 watts of power. Although it will run flat in just two minutes. The higher the C-rate the better the battery’s performance although most electric bicycles will only require a C-rate of less than ten.

Larger long-range batteries need much lower C-rates as they are big enough to provide power to the electric motor without getting stressed. If the peak-power of a motor is 1,000 watts the battery should have a C-rating that provides sufficient watts to match this. A 500 watt-hour two-c battery would meet the above criteria. Lithium cobalt oxide batteries can produce a C-rate as high as 100-c.

Electric Battery Terms: Cycles

Finally, there is the amount of cycles a battery can undertake before its capacity gets severely reduced. A full cycle, also known as a 100 per cent depth of discharge is when the battery is run completely flat. Batteries will last longer if they are only discharged to 80 per cent. The 20 per cent reserve helps to greatly prolong their lifespans.

Knowing electric battery terms helps you to choose the right battery to meet your needs. However, it also provides you with the information to get the best performance and lifespan out of your electric battery.

Recommended Reading

Visit Endless Sphere for more information on electric bikes and suitable battery chemistries from one of the best internet forums on the subject.

You may also wish to check out more in our battery series Lithium Batteries: The Ideal Choice For Electric Bicycles and Electric Batteries Of The Future.

Electric Bicycles: The Electric Revolution For Everyone and Electric Cars: Welcome To The 21st Century.

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