August 26, 2017

Electric Bike Battery

electric bike battery

Electric Bike Battery

Everything you need to know about electric bike battery

Electric Bike Battery: battery is the most important part of your electric bike. It defines the amount of energy you can count on, while riding an electric bike. Better (lighter and more powerful) battery has less weight, consists more energy and extends the distance you can use the assistance. Therefore, it is always good to know more about different battery types and their capacities before you are going to buy an electric bike.

Electric Bike Battery Life

Electric bike battery can last several hundred charge cycles in theory. But how many cycles exactly? That depends on the battery type concerned. Battery lifetime depends on the way you take care of your battery. If you store your battery in dry conditions and protected from temperature changes, it will last longer. Normally, an electric bike battery becomes less efficient after 3 to 5 years of regular use.

The lifetime of Electric bike battery is mainly determined by the battery type. The most commonly used batteries on electric bikes are lithium batteries. Lithium batteries may hold up to 1000 charge cycles or even more. With nickel batteries you can expect around 500 cycles.

Electric Bike Battery Types

There are three types of batteries commonly used for an electric bike. Their difference comes from the use of different chemical combinations. These combinations are – Lead Acid (PbA), Nickel combinations and Lithium combinations. What’s the difference you may ask?

1)Lead Acid Batteries (PbA)

electric bike battery lead acid
Lead Acid batteries are the oldest, cheapest and heaviest battery option. Only couple of years ago, most of the electric bikes sold worldwide (nearly 80%) used Lead Acid battery packs, but these days are over. Life-cycle of the Lead Acid battery is the shortest (don’t expect much more than 200 cycles). For electric bikes, the most commonly used Lead Acid packs are 12-48V with 7Ah-12Ah capacities. It is important to know that you should only expect about 60-70% of the promised Amp-hours. The weight of the lead acid battery is simply too much for a decent 40-50km range of bike ride, therefore expect do cover shorter distances.

2)Nickel combinations (NiMH and NiCad)

electric bike battery nickel
The most common Nickel combinations are Nickel Cadmium and Nickel Metal Hydride. Nickel combination batteries have better Life-cycle than Lead Acid batteries. Nickel Cadmium (NiCad) batteries are about 20% heavier than Nickel Metal Hydride (NiMH) or Lithium combinations, but they are still weight savings over Lead Acid batteries. NiMH batteries in the other hand, are 30% less voluminous than a NiCad batteries of the same capacity. They have similar discharge and charge characteristics, but NiMH batteries are available in higher capacities than NiCad packs. Because NiMH is safe for disposal in the landfill, the NiCad has almost completely disappeared.

3)Lithium combinations (LCO, LiPo, Manganese and LiFePO4)

electric bike battery lithium
Lithium-ion have become the default battery type on the market (more than 90%). Lithium technology is the newest and is considered to be the best. Almost all the electronics nowadays, that have plug-in charger, have Lithium batteries. Li-ion batteries are widely used because they last longer and generate more power and weight less than other battery types. On the negative side, they require all kinds of electronic features to prevent them from self-destruction or even catching fire! Of course, this is not exactly your problem. Manufacturers have already eliminated the dangers and guarantee you a safe ride. But like all the better things in this life, they come at higher price! There are four widely known and popular Lithium combinations for electric bikes.

a)Lithium Cobalt

Lithium Cobalt (LCO) is the lightest electric bike battery available and claimed to have much higher energy density than other lithium batteries. Battery cells are slightly more unstable than other types and require very strict quality control and electronic monitoring at all times, so it is not recommended to use it for home-built electric bike.

b)Lithium Polymer

Lithium Polymer (LiPo) is another light battery option. It contains no liquid and do not require heavy protective cases that other batteries need. No liquid theoretically means that they should be more stable and less vulnerable to overcharge, damage or abuse. But it’s lightness also comes with some disadvantages. LiPo batteries are produced in a thin plastic pouch rather than a metal can, making them quite vulnerable to physical damage. These batteries are often made with cells that are only rated to 1C or 2C (don’t usually deliver a very good Life-cycle and are less powerful). In the past, LiPo batteries also had a reputation for being fugitive. But nowadays, companies are making these batteries quite stable and safe.

c)Lithium Manganese

Lithium Manganese is perhaps the most common chemistry used for electric bikes. It is a bit heavier than other Lithium combinations, but is also safer. Most of the Lithium Manganese batteries use rectangular steel canned cells and have good discharge capabilities (this chemistry holds the voltage better and more stable than Lithium Polymer – which tends to have a linearly declining voltage, leading to an electric bike that starts off hasty and finishes sleepy). It is considered as one of the best (safest) options on the market.

d)Lithium Iron Phosphate

The Lithium Iron Phosphate (LiFePO4) battery has received a lot of hype and media attention few years ago. LiFePO4 batteries were claimed to have longest Life-cycle (even up to 1500 to 2000 cycles). LiFePO4 batteries are a bit lighter and a bit more expensive than NiMH, but they could be quite economical in the long run.

Electric Bike Battery Packs

Battery packs in other words are individual cells connected together. Depending on chemistry, each cell has more or less constant voltage. For Nickel, each cell has about 1.2V, Lead Acid cell has about 2.0V and Lithium cells have about 3.7V. For example, if you are looking at the electric bike with 36V, it could have 30 Nickel cells, 15 Lead Acid cells or about 10 Lithium cells.

Voltage, Amp-hours, Watt hours

Electric bike usually comes with a 12-48V battery pack, containing 5-20Ah capacity. But what does it mean?

Before you are going to buy an electric bike, you need to know what to expect from it. The first step would be to calculate Watt hours. And it is quite easy to do, simply multiply the voltage by the amp hours. For example, an electric bike with a 36V 8,8Ah battery pack has 316 watt hours. A 24V 10Ah battery pack has 240 watt hours.

Calculating Estimated Distance

The next step would be to calculate the performance of your Electric Bike Battery in terms of estimated range. To do so, you need to know that average cost of every mile you travel is about 20 watt hours. For example, if you have a battery pack containing 316 watt hours you can go about 15-16 miles. With 240 watt hours you can go approximately 12 miles. The distance can vary widely depending on how and where you ride (if always riding uphill or at full speed). Even your own weight or the weight of your carriage can make a big difference. But the calculation above should give you the picture.

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Maximizing the lifetime of your electric bike battery

1. Charge your battery for 12 hours.
2. Use it regularly. Ride your bike a lot, use your battery often.
3. Avoid temperature extremes both in usage and in charging.
4. Do not leave your battery on the charger for multiple days.
5. Never store your battery for extended periods with an empty or very low charge.
6. Full charge it about once every 3 months.