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What You Need To Know About Electric Bike Batteries

Posted by Trevor James on

 

What you need to know about electric bike batteries is quite simple really that you could make a checklist of them in no time.

- An electric bike needs a battery
- It affects the length of time your bike could assist you in cycling
- The power output is assisting the electric motor to spin and also drive your bike forward
- The battery will need recharging every 30-50 miles
- They come in different cases and could be located on different parts of the bike
- You could buy extra ones as well as replacement ones
- You could usually take the battery off the bike to recharge it or keep it safe

There are two main types of batteries used in the electric bikes we sell, lithium-ion (the same type of battery that's in your smartphone, tablet, and laptop computer), and a sealed lead acid battery (the same type that's under the hood of your car). Let's go over the features and benefits of each one.

Lithium-ion Batteries

This type of battery has many benefits including a lighter weight, longer lifespan, safer to use, and the capability to charge faster. The only drawback to this type of battery is the higher price tag. You'll find li-ion batteries in almost all higher quality electric bikes because of all their benefits and the price has of manufacturing has decreased significantly over the last few years. There are many different types of lithium ebike batteries to choose from. LiFePO4 batteries are a few of the heaviest and most expensive lithium batteries but are also the safest and longest lasting. LiMn2O4 and LiNiMnCoO2 batteries are in the mid range of lithium batteries based on size, lifespan, safety, weight and cost. They are a great middle ground in all aspects. LiPo’s are the lightest, cheapest, smallest and most powerful lithium batteries. The disadvantages include short lifespan and the tendency to ignite into big fireballs if they are not properly cared for.

Advantages of Lithium-ion batteries

Now that you are familiar with different types of lithium ion batteries, we are going to look at how the lithium batteries stack up as a whole. The first advantage of lithium batteries is their small size. You could fit a lot of lithium ion batteries on a bicycle frame. This could give your ebike some real impressive range. Two or three medium to large capacity lithium batteries could fit easily on a single bicycle, which gives a potential range of 100 miles or more. I think that this would be amazing for guys who are not bothered with sitting on their bikes for three to five hours at a time, or for some reason do not want to charge up for weeks.

Lithium batteries for ebikes usually come with specific bicycle mounting points which makes them easy to attach to the bike frame, rear rack or seat post. If you prefer another kind of lithium battery with no electric bike specific mounts, you are going to have to put it inside a bag on the bike which is a good option, and something pretty preferrable.

Lithium batteries are small enough to let you place your batteries almost anywhere on your bicycle. This is applicable for guys who wish to assemble their own pack or use lithium batteries wrapped with heat sink rather than hard case lithium batteries that have prefabricated bicycle frame mounts. This could help distribute the weight about or hide the batteries in order to create a stealthier bike.

With the exception of RC LiPos, lithium batteries endure much longer compared to lead acid batteries. LiPo batteries are rated usually only for a few hundred charge cycles but LiFePO4 batteries continue after thousands of charge cycles. Each manufacturer gives ratings to their batteries differently, but many LiFePO4 ebike batteries are going to be rated for somewhere between 1,500 to 2,000 charge cycles.

 

Sealed Lead Acid Batteries

When it comes to lead acid batteries for using electric bicycles, you would be searching for what is called a “sealed lead acid” or SLA battery. SLAs come sealed in a hard plastic case and could be turned in any kind of orientation safely without acid leaking. This makes them appropriate for ebike use. This type of battery is less expensive to manufacture than lithium-ion batteries, so it is used in electric bikes priced under $800. These batteries are much heavier than li-ion batteries, often weighing upwards of 20 pounds. They are also more dangerous due to the poisonous lead, especially those that you call wet cell lead acid batteries, contained within the sealed cells. These batteries are the same type that can be found under the hood of your car, so the same safety precautions that are taken when handling a car battery should be taken when handling an electric bike sealed lead acid battery. They could leak when you turn them around upside down and this is especially important for electric bikes than cars as they are more likely to get knocked over compared to that of a car. As already mentioned, lead acid batteries are much larger and heavier than lithium batteries, which limits placement on bicycles. They almost do not come packaged with ebike specific mounting hardware and this means that they generally have to go in a bag on the rear rack or in panniers on either side of the rear wheel. Placing them up high on the rack is not a good idea either since it is not going to affect handling in a negative way. In general, you want to mount your batteries as low as possible in order to keep the center of the gravity of the electric bike lower to the ground. This is going to improve the handling of the bike.

Advantages of lead acid batteries for ebikes

The main benefit with this type of battery is the lower cost which allows beginners to enter the e-bike world, experience the fun, and then upgrade later when they can afford to. Another advantage of lead acid batteries is the price: very cheap. Lead acid batteries could be purchased from a lot of different online retailers and local stores. Buying SLAs locally will save on shipping and makes them cheaper. A lot of hardware and electronic stores have them. Even Radioshack has them, although you are going to pay more there.

Also, lead acid batteries have high power output potential. Lithium batteries in general do not like to handle too much current. SLAs, on the other hand, could give huge amounts of current. If you are planning a very high power electric bicycles, SLAs could be a good option for you.

Disadvantages of lead acid batteries for ebikes

Among the main disadvantages of lead acid batteries is their weight. There is no denying that SLAs are heavy and if you guessed that it’s because of “lead” then you are correct. You would need a strong mountain solution on your ebike so that you can handle the extra weight of SLAs. You need to be aware that lugging the extra weight around will impact negatively the range. The best way to improve the range of any kind of electric vehicle would be to reduce weight and SLAs follow the opposite rule in this aspect.

Another disadvantage of lead acid batteries is the short lifespan. Most people claim to be rated for over 200 cycles, but in practice you would usually find a lot of SLAs start showing their age at about 100 cycles. They are going to work as they get up in years (or charge cycles), but you will begin seeing your range quickly decreasing. If you travelled 15 miles for every charge when the SLAs were new, a year later you are going find yourself going past 10 miles.

SLAs come in 12V or 6V increments, which means that you have to build your battery pack by combining the smaller SLAs in parallel or in series to have the right kind of voltage and capacity that you are aiming for. This could be both a disadvantage and advantage. It gives you extra room for customizing but might need extra work to combine the individual SLA batteries into a larger pack together. This type of battery is also much less environmentally friendly than the lithium-ion batteries, so waste is a big issue after the battery's lifespan is up after a few years.

Which Is Better?

It is really up to you but it is actually lithium-ion. If you experiment on new ebike parts and want to test different battery voltages for different speeds, it is better to use lead acid batteries because you could try many different voltages with very cheap batteries. Then if the results of your lead acid battery tests show you whether you want to go with 36V, 48V or 60V, you can then commit to getting the right lithium battery.

There are only three instances where using lead acid batteries are preferred rather than lithium-ion.

1. You are building an electric bike on a really tight budget.
2. You are planning to build an electric bicycle, that could easily carry SLAs without stability or balance issues.
3. You wish to test out different battery voltages on the system. You need to make sure that your controller could handle the range of the voltage.

Other than these cases, the advantages of lithium batteries really outweigh that of SLAs. Of course, for your e-bike, you might have reasons that could sway you either way. Overall, your electric bikeis about you.

Other Types of Electric Bike Batteries

Nickel Cadmium (NiCd) Electric Bike Batteries

In terms of weight, nickel cadmium (NiCd) batteries contain more capacity compared to lead-acid battery and capacity is a very important consideration when it comes to electric bikes. But, nickel-cadmium is not cheap and cadmium is a really hard-core pollutant and difficult to recycle. NiCd batteries, however, are going to last longer than lead acid batteries. The truth is that since they are so difficult to recycle or dispose of safely, NiCd batteries are quickly becoming outmoded. They are also not a good battery type, despite the price.

Nickel-metal Hydride (NiMh) Electric Bike Batteries

NiMh batteries are a bit more efficient compared to NiCd batteries but are also more expensive. A lot of people report that NiMh provides only little improvement in range compared to NiCd. That aside, they are going to last longer and are easier to get rid of correctly. NiMh batteries, however, are getting rare since the market is getting taken over by Lithium-ion batteries.

Lithium-ion battery variations

Lithium Iron Phosphate (LiFePO4)

This is among the firest widely used Li-ion batteries that has one of the longest life cycles (2000+) and very stable chemical composition. It has a somewhat low discharge rate, which makes it unsuitable for high power demanding electric bikes.

Lithium Manganese Oxide (LiMn204)

This is a slightly smaller, cheaper and lighter lithium-based battery compared to lithium iron phosphate. It also handles charging as well as discharging slightly better. However, because they have a shorter life span (600-800 cycles only). They could be somewhat heavier compared to lithium polymer and lithium cobalt batteries but they are also safer. A few manufacturers claim that it has higher power because of better discharge capabilities and this bike could be seen in a few higher end electric bikes.

Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2 or NMC)

This battery has a safe chemistry which could deliver higher power in a smaller, lighter package. It is newer compared to LiMn2O4 and LiFePO4, so it could be rigorously tested yet, however is thought to be gaining shares in market.

Lithium Cobalt (RC LiPos or LiCo)

Lithium Cobalt are usually referred to as RC LiPo batteries because of their common for the RC or remote controlled airplane industry. These batteries are very compact, with high power output, light weight and cheap. However, they are also a few of the least stable among Li compositions. The batteries could easily ignite if they are not handled with care. Electric bike LiPos packs are usually designed with cells which are rated only to 1C or 2C, and could not therefore usually deliver a very good life cycle count. The cells are made in a thin plastic pouch instead of a metal can, which would make them vulnerable structurally if they are not supplied with a sturdy enclosure. So, you need to make sure to discover who the manufacturer is and if their LiPo batteries have passed the entire UN 38.3 overcharging and puncture tests and not bursting into flames.

Electric bikes in the UK either come with Lithium Ion or Li-ion or Lithium Polymer (LiPo) batteries. In China, however, lead acid batteries are still the common ones which are used. In 2014, based on the China Bicycle Association/ IdTechEx – 35 million ebikes were sold on the Chinese market, and just 2.8 million of them had lithium battery.

Due to the problems of quality and weight, lead acid batteries are not quite common in the rest of the world. For example, in Europe, acid lead batteries signify less than one percent of the whole while 96.5 percent is taken by lithium ion and two percent by LiPo. How long your battery lasts depends on the power of the battery (usually 24, 36 or 48V), the bike’s power, the bike’s battery management system and the way you use your bicycle.

Some ebikes allow you to select different levels of assist to make battery life or speed the priority. This makes the prediction of battery life difficult. In general, you can expect somewhere between 25 and 70 miles of travel on one charge of an electric bike. If you are riding hard on full power, you should expect less. You must learn to manage your battery life well and you might get more.

A lot of retailers recommend to charge the battery at least once a month if the e-bike is not used much, and say that if the e-bike is ridden, the stronger the battery will be. All batteries, however, are going to degrade in time and they will have to be disposed and replaced. If that time comes, it would be best to ask your local retailer how to get rid of the battery. You should still remember that local authorities need to give disposal and recycling facilities.

Batteries are located on the e-bike in different placed depending on several factors, especially the shape of the frame of the electric bike. A lot of electric city bikes, actually more than half, will have the battery mounted on the carrier rack, while mountain bikes usually have them located on the down tube. Batteries are the heaviest and also the most expensive part of the e-bike. A lithium battery (36V and 10Ah) could cost around $200, but the prices vary. Technology is fast advancing so you need to check with your retailer first to make sure that your battery is not outdated or hard to replace.

The Main Specs of Every Battery You Need To Know About

Each type of battery has two main specifications that determine how powerful the rush of electricity is sent to the motor and how big the storage capacity for electricity is. These are known as volts and amp-hours respectively.

Watch this video to learn more about electric bike batteries:

Volts

The amount of voltage the battery is rated means how powerful the rush of electricity is sent to the motor. It also means the force that makes the electricity move through a wire. Li-ion cells would be around 3.7V. E-bikes are designed to run on 24, 36, or 48 volts. Other factors come into play as well like the size of the wires used, how big and strong the motor is, and how much voltage the controller is made to handle, but the battery's voltage rating is where it all starts. Some entry level electric bikes come with a 24-volt battery, but this is rarely enough to get you up to speed as fast as you would like to. The industry standard these days is 36 volts because this is the minimum required to give you a quick take off and give you that feeling of excitement when you pull the throttle. Some e-bikes come in 48 volts as well, which can give you great torque power for climbing hills, but 36 volts is all you need for a wide application of uses, hilly or flat.

Current

Electrical current is just moving electric charge. In layman’s terms, it is the electricity moving in a wire. It’s unit of measure is Amperes (Amp or A).

Watt

Watt is a unit of power and is quantitatively defined as 1 joule per second. It could be used to express the rate of energy conversion or transfer with respect to time. An analogy would be a laborer working for 8 hours straight having an output of around 75 Watts.

Amp-hours

The amount of storage capacity the battery has to hold electricity is known as the amp hours. Amps can be related to the gasoline in a tank. They are simply how much electricity the battery can hold. The hours in amp-hours means how many amps there are per hour of usage. You'll often see 8ah, 10ah, 12ah batteries or more. This is how big your e-bikes "tank" is. We suggest going with a minimum of a 10ah battery as this is enough to get your around for between 30-40 miles of flat or slightly hilly usage. This measurement depends on other factors as well, like wind resistance, rider weight, and steepness of the hills, but generally speaking, 10ah is enough for everyday use. 

Watt Hours

This is the important figure when you compare how far a given battery pack is going to take you and not the amp-hour capacity. The watt-hours stored in a battery pack is estimated by getting the actual amp-hours and multiplying it by the voltage of the battery pack.


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