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What You Should Know About Electric Bikes

Updated on September 4, 2012

Electric Bike In The Know

When you mention electric bikes to the uninitiated they imagine what an electric bike must be like. I can guarantee that no one imagines the huge variations in performance and feel that are on offer.

When you are comparing traditional cycles it is quite easy to read the specification and look at the bikes to see what the differences are and where your money is going. With electric bikes the differences cannot be seen, they are electronic or contained in a format you cannot easily compare.

It is understandble if you are confused by conflicting sources of information. It takes years to truly understand all the technology used by ebikes and the interplay between them and the resultant cycling experience. Yet enthusiasts with little knowledge are keen to tell the world what they know.

The performance of an electric bike is not all about the latest battery technology (an over simplification) it's a combination of battery chemistry, control electronics, motor core composition, wireharness and connectors used, quality grade of all materials, efficiency of the system and attention to detail at the factory.

Just as motorcycles or cars that look the same can give very different driving experiences so can electric bikes. It is so important to test ride or get honest, knowledgeable advice.

You might be surprised by how the power integrates with your riding style. When the power comes in; when it cuts out and how smooth or aggressively it does both. Are the gears suitably matched to the power and for your intended use? For instance (deep breath) if you have weak knees and you have an ebike with a speed sensor and dérailleur gears stopped in top gear you may find it very hard to start because you get least assistance while the pedals are turning slowly and of course you cannot change dérailleur gears until you are already moving...chicken and egg anyone? This does not necessarily rule out this combination of components for people with weak knees...actually the advantage can be that you can reach full speed in a lower gear while applying minimal pressure to the pedals and therefore less strain to your knees. It will be important that the manufacturer has thought about the practicalities of their design and programmed the control unit accordingly.

Electric Bike Performance

The performance of an electric bike is not all about the latest battery technology (an over simplification) it's a combination of battery chemistry, control electronics, motor core composition, wireharness and connectors used, quality grade of all materials, efficiency of the system and attention to detail at the factory.

Just as motorcycles or cars that look the same can give very different driving experiences so can electric bikes. It is so important to test ride or get honest, knowledgeable advice.

You might be surprised by how the power integrates with your riding style. When the power comes in; when it cuts out and how smooth or aggressively it does both. Are the gears suitably matched to the power and for your intended use? For instance (deep breath) if you have weak knees and you have an ebike with a speed sensor and dérailleur gears stopped in top gear you may find it very hard to start because you get least assistance while the pedals are turning slowly and of course you cannot change dérailleur gears until you are already moving...chicken and egg anyone? This does not necessarily rule out this combination of components for people with weak knees...actually the advantage can be that you can reach full speed in a lower gear while applying minimal pressure to the pedals and therefore less strain to your knees. It will be important that the manufacturer has thought about the practicalities of their design and programmed the control unit accordingly.

OK now you have found the honey pot!

Batteries are electrochemical and they have their own personalities, few battery packs are identical in their behaviour. 2 people can buy the same ebike model at the same time and have completely different experiences with their batteries. The differences between budget & well made ebike batteries are significant. As an example many of you at one point or another may have opted for a cheap generic battery over Duracell and realised that the economy is a false one for you and a waste of materials.

We have studied the theory behind batteries (this can keep you busy for a long long time) but the most useful information has come from our customers. No matter what the lab tests say there is no replacement for the dynamic testing of end users and all of that rich feedback we learn from and translate into the best services for our customers.

The electric bike industry has been waiting for your interest to become significant enough to allow more effective battery technologies to be offered at reasonable prices. That is starting to filter through and the following are the main pros and cons of the most frequently used battery technologies.

Sealed Lead Acid (SLA)

Pros: medium energy density, maintenance free, tried and tested on electric bikes, cheap.

Cons: heavy, battery cells can age quickly and die, no fast charge option, no storage option.

Nickel (NiMh & NiCd)

Pros: medium energy density, fast charge the norm, medium weight, serviceable.

Cons: Need interval discharges and servicing, suffer from memory effect, performance radically reduced in cold weather, no storage option.

Lithium-ion (Li-ion) If any store tells you that their ebike battery 'is the latest technology' ask them what that means. If they say 'Lithium' ask them which type of lithium ('ion' or 'polymer' refer to the electrolyte that holds the chemistry not the chemistry itself so don't accept those as answers) and what that means to the performance of the machine.

You need to discuss which Lithium chemistry suits your requirements the best, otherwise you may not get the performance you envisage and unsuitable use of the battery may lead to a shorter life with high replacement costs.

This is where it gets really interesting from now and into the future and some basic knowledge is required for you to understand the role of the differing lithium chemistries.

Geek bit:

Energy is released when the ions (in this case lithium-ions Li˟) move from the positive anode to the negative cathode through the electrolyte. The anode is usually graphite, the electrolyte is usually a solvent based lithium salt. The currently interesting and available chemistries are mainly focused on changes to the Cathode material which is usually a lithium based oxide. On ebike batteries you will currently see the following Cathode Oxides: Lithium Manganese LiMn2O4, Lithium Nickel Cobalt Manganese LiNiMnCoO2, Lithium Manganese Cobalt LiMnCo, Lithium Iron Phosphate LiFePo4.

The exception to the above is Lithium Sulphur LiS which uses a lithium anode and a sulphur solvent as a cathode. The potential for Lithium Sulphur is very exciting because each sulphur particle can hold 2 lithium ions compared to less than 1 ion for most other chemistries.

Talk to us about which lithium chemistry is the best fit for your requirements.

General

Pros: Very lightweight, very high energy density, durable, no maintenance, fast charge, can be stored.

Cons: Expensive, can be unstable, cells charge and discharge at different rates.

Lithium-Polymer (Li-Po)

Pros: Lightest battery available, highest energy density, no maintenance, fast charge, proven high level of stability under extreme laboratory tests, flexible shape, low self discharge, can be stored if care taken, wide operational temperature range.

Cons: Most expensive, will suffer if incorrectly stored for a short time, can suffer thermal runaway and pose a fire hazard if charged after a period of incorrect storage or if the BMS has catastrophically failed, charging can be complicated.

HOW TO GET THE BEST FROM YOUR BATTERY

SLA: Like a car battery your lead acid battery takes a few cycles to get to peak performance, once there it should be topped up as often as possible. The reason you get a 3 year warranty with many car batteries is that they are being charged every time you run the engine and this means they rarely experience 'deep discharges'. The less full cycles you do the longer your SLA battery will last so top up when you can.

Nickel: NiCd and NiMh batteries are tremendously robust; they can deliver high amounts of current and be 'exercised' back to life when they start to die. As with most batteries the most important thing is to keep them topped up, however they are known to suffer from 'memory effect' or 'floating voltage'. To address this problem they need to have periodic full discharges and as they age the number of full discharges required each time increases. For a NiCd battery this period is every month and for a NiMh it is every 3 months. If a NiCd battery appears to be almost completely dead it may be brought back to health by isolating each group of cells and charging with very high currents, this should be left to someone qualified for the task.

Lithium: No matter which type of exotic lithium chemistry is used the battery maintenance follows a simple rule: keep it topped up! A lithium battery that will perform say 800 full cycles may well perform 2,000 half cycles. The trick is to get a bigger battery than you need for your journey or carry the (usually small) charger with you and take advantage of 'opportunistic charging'. Reducing deep discharge cycles increase lifetime and performance over the lifetime.

If the battery will not be used for more than 4 weeks it should be stored at a storage voltage of approximately 40% of it's operational voltage, e.g. a 36V battery should be stored at roughly 39V.

THE FUTURE BATTERY

Lithium batteries are the main focus for battery R&D; there are very good reasons for this such as: high energy density (energy/litre or Kg), low weight, flexibility of application, reduced internal resistance, longer life cycle etc.

High Energy Density/Low Weight: The honey pot of honey pots! A number of companies and universities around the world are claiming that they can increase the energy density of Lithium based chemistry by over 10 times....that would truly speed up this pending transport revolution. Prof' Peter Bruce of the University of St Andrews in Scotland is one of the people claiming success in this area.

Fast Charging: Many companies have now demonstrated technology for rapidly charging batteries, especially lithium batteries. There are products available on the market already and there are batteries designed to cope with the high currents required. Altair Nano and Toshiba have developed lithium batteries capable of taking huge currents without thermal overload. The key is the low internal resistance and without getting too technical, both companies achieve this by eliminating graphite in the porous separator and using nano particles to absorb the lithium ions.

Long Life: a bonus of low internal resistance is that an increase in longevity occurs. Battery life spans are normally related to the number of full charge and discharge cycles a battery can do before it looses 30 to 40% of it's capacity. Altairs Nano Titanate battery has now achieved over 20,000 cycles and Toshiba's has achieved 9,000. In the future you may well have to include your batteries in your will!

What exactly is an electric vehicle (EV) battery?

An electric vehicle battery is a high current battery. This is very different from most consumer electronics batteries. And the EV battery is much larger, with much more energy stored. (Do NOT test EV batteries by putting your tongue on the contacts! And do not short the terminals to see if you get a spark!)

Keep in mind that good EV batteries have enough energy to carry a 90 kg man over hill and dale for close to 20 miles. That is a LOT of energy!

A battery is not just one solid piece, but a collection of "cells". The cells are one complete unit of anode, cathode and electrolyte that produce electricity from a chemical reaction in the cell.

Each cell type (also called a cell's "metallurgy") has a nominal voltage. For example, NiMH (Nickel Metal Hydride) is about 1.2 volts per cell and thus we need to combine a bunch of cells to get the voltage we use in an electric motor. So 30 cells gives us 36 volts (n

Electric Bike Motors types

The Basics

The component that provides a turning force to assist your pedalling.

Through continuous improvement and increased investment (thanks to you) motors are becoming smaller but like any of the latest technology the best ones are more expensive. Better motors will have lighter more durable materials and sometimes they will be smaller in size and weight while still offering the same power output.

There are 3 main types of motors used on ebikes and there are pros and cons to each.

Motor Types

Brushed motors are not given good press. They are larger, heavier and noisier than their brushless counterparts and they need to be serviced. Doesn't look promising for the poor old brushed motors. However if you consider the ability to service brushed motors for a low cost (some at intervals of up to 16,000 miles) and that with this service the motor can continue as new your perspective may start to change. Brushed motors have proved to be robust performers, offering reliable hill climbing at a lower price point.

Brushless DC motors (BLDC motors) can be made smaller, lighter and certainly quieter than brushed motors. The technical differences are not as important as the relative performances under different applications and although all the theory points towards BLDC being the best choice for ebikes we have found over the years (since late 2004) that good brushed motors can be more robust under demanding circumstances and can be better hill climbers for a given power input. Although this may be changing with the introduction of the latest type of sensorless or permanent magnet BLDC motors.

Sensor-less brushless motors are usually found in 2 phase or 3 phase and are very similar in construction to AC induction motors which contain permanent magnets and are often used for industrial applications. We have noticed a significant improvement in the reliability of BLDC since the introduction of sensorless hub motors. The hall effect sensors are no longer required because the position of the armature can be detected using EMF or magnetic field detection and this reduces the electronics required on board the motor. Viola! Improved reliability.

*There is always an exception and for sensorless BLDC motors it is the friction drive systems which although even smaller, even lighter and even quieter suffer from slipping of the drive and the resulting activity in the electromagnetic characteristics can paralyse the control units. This comment is based on our experience of these friction drive motors since 2006 on the Protanium (Diavelo) and Schwinn ebikes, designed by Protanium and the Tongxin motors available from the same time and used on the 'Nano' kit systems.

Brushless motors have a linear power speed response which means that maximum torque is available from a standing start and reduces smoothly through acceleration.

Motor Power

Something that isn't mentioned often is the efficiency of a motor. What power are we talking about when we state 200Watts or 250Watts, is it input or output power? Whenever power goes into a hub motor it drives the shaft which turns with a measurable force Nm. The more efficient a motor the more Nm you get for the same input power. The difference between the input power and the output power gives us the efficiency. Power is lost due to resistance in the copper coils, due to reluctance between the magnetic fields, due to the harmonics generated when operating.

Efficiency is one factor that explains different performances of similarly specified ebikes. Ideally a low-medium nominal power such as 200 to 500Watts can be accompanied by a high peak power of say 1.5KWatts for the best all round performance. This gives you the power reach you might need without creating unhealthy demands on your battery system and your wireharness.

Peak Power - this is the maximum power output a motor can achieve for a few seconds. It is a better indication of performance than than the nominal power which is usually quoted.

Position of the Motor

There are 2 commonly used drive positions for the motor on ebikes. You guessed it...there are pros and cons for both systems:

Why A Hub Motor?

With electric assisted and electric powered bicycles, scooters and motor cycles selling in the millions of units world wide - the huge majority of them using hub motors - hub motors have progressed from a peculiar way to power an electric vehicle to the one of the most useful and practical drive systems for electric vehicle (EV) applications.

For electric bikes, the advantages of a hub motor are:

1.The motor is in a space that is not otherwise used in the conventional designs of bicycles.

2.The motor can be installed without significant changes in the frame or the ordinary configuration of the machine making them perfect for conversion kits.

3.Hub motors are simple and self-contained, thus reducing overall cost of the vehicle by enabling the designer to use off-the-shelf parts and designs for their vehicle.

4.The motors are sealed and mostly maintenance free.

5.The motor is directly attached to the driven wheel, improving efficiency.

6.The centre of gravity is relatively low, improving balance.

7.It looks nice!

8.If it needs to be serviced, repaired or replaced it can be easily accessed.

9.If it does need replacing it usually does not affect any other component.

10.With hub motors we can replace one hub motor with an updated version if the old one is no longer manufactured. This ensures your product will never become redundant.

11.If you have a front hub motor then you can have a 2 wheel drive bicycle assuming you will provide human power to the rear wheel. This can have a number of useful consequences.

The Drawbacks of Hub Motors

For hub motors, the drawbacks are:

1.The cost is higher because the motor is more complicated than other kinds of electric motors.

2.Because the motor is sealed against water and dirt, getting rid of heat that the motor generates while turning can be a problem, luckily many controllers monitor motor temperature.

3.The wheel is heavier with the addition of the motor...by as little as 2.3Kg

4.There are hundreds of hub motor manufacturers in China and all of the motors look the same but only a handful are what we could call a reasonably made product.

Why a Crank Drive Motor?

Since Panasonic and Yamaha put their considerable commercial weightiness behind this type of drive system sales in Europe have rocketed. Sales in the US have been far slower due to the systems lack of how do I put it....grunt.

Despite the performance drawbacks crank drive systems can be the 'nicest' systems to ride.

Advantages of a crank drive system:

1.Standard lower cost motor design can be used with a single external drive shaft and a fanned heat sink casing.

2.The motor can be smaller because the fanned casing allows for heat to be more effectively released.

3.The motor is generally in or near the bottom bracket so the weight is low

4.The motor can be kept near its optimal operating speed by using the bikes gearing.

5.By using the bikes gearing the bike can provide more effective assistance on hills than same power hub motors.

6.Because of the low power levels used the systems tend to be reliable.

Disadvantages of a crank drive system:

1.The units are always sealed and contain almost all of the components, motor, controller, and torque sensor. This means if one component fails the whole system has to be replaced increasing the cost of maintenance and repair.

2.The systems are proprietary and if parts become unavailable it will be very expensive to adapt another system to fit.

3.The output power and therefore performance is limited by the strength of the chain and the sprocket. Standard chains and sprockets are used and these are designed for human power only, which means the amount of mechanical power that can be added is relatively small.

4.There will be increased maintenance on the drive chain, including all cogs and sprocket.

The Bionx Montague Paratrooper

The Montague Paratrooper folding mountain bike meets the Bionx electric conversion kit to give birth to a state-of-the-art folding electric mountain bike that offers speeds in the 20's, awesome hill climbing assist and a range of up to 60 miles on a 3-hour charge.

All of this comes on a military-grade mountain bike that folds for easy transport and the whole thing weighs only 43.2 lbs - extremely light for an electric bike. A 36-volt Lithium-Ion battery pack is mounted down low on the frame providing the perfect center of gravity for balanced riding in the dirt or on the pavement. This is an exceptional folding electric bike that is delivered fully-assembled and ready to ride.

Kalkhoff Pro Connect XTR S10

The 2012 Kalkhoff Pro Connect S10 DL with Shimano XTR gears and new 36V 350W Panasonic motor

The best electric bike in this price range, fast solid and reliable. I travel to work every day, 110 miles a week, plus travel to friends, shopping and everything else in between. It's the business for tackling hills. I got rid of my car (live in London) so this is my main mode of transport! It has helped by saving me money in travel costs and gym fees! A definite worth while purchase."

This sporty bike puts commuters in the fast lane. The Pro Connect S has a high-performance pedelec motor for extra powerful propulsion, allowing you to accelerate to up to 40 km/h. So you'll be able to complete longer journeys quickly and easily.

But acceleration is not the only thing that matters: the Magura Julie Speed hydraulic disc brakes will bring you safely to a halt, while the Suntour NCX-E fork with lockout ensures a comfortable ride. The Shimano XTR 10-speed derailleur gears enable the ideal pedalling cadence at any speed. The top-quality AXA LED NANO front light with 40 lux guarantees the Pro Connect S perfect performance. This model includes a variety of Carbon parts, saving around 700 grammes compared to the Pro Connect S and maximising ride quality and responsiveness.

Infineum Extreme

The secret to this stylish and interesting machine is the patented stackable battery system. Each Infineum battery added increases your range by another 7 to 15 miles and Powacycle say there is no limit to the number of batteries you can stack. It is worth noting that this is the first electric bike with a 2 year battery warranty at this price point.

We are reintroducing this bike after several improvements from Powacycle. It is worth considering if you want a lightweight electric mountain bike that looks good and doesn't look electric. It is the lightest eBike in its class, finished to a high standard with gentle stealthy assist.

The Infineum has a cycle pc interface that tells you all the usual info plus how far you can still go on your current battery charge.

The Infineum has a cycle pc interface that tells you all the usual info plus how far you can still go on your current battery charge.

Performance

Max Range 7 to 15 miles with one battery

Max Power 612watts

Nominal Power 250watts

Max Motor Speed 15 mph

Peak current 17Amps

Ave' Charge times 2 to 4 hours

Cytronex Powered Claud Butler Urban 500

The Claud Butler Urban 500 is ideal for commuting, with high specification components like the carbon forks, double wall rims and of course mounts for a rack and mudguards.

Fitted with Cytronex Power assistance for multi geared bikes (see www.cytronex.com), when you want assistance just press the right hand Boost button. You can either select full power on the left or low speed for steep hills, cycle paths or sightseeing. Whenever you depress the rear brake lever or push the boost button again the power stops immediately. For safety you need to press the boost button to start again.

The Cytronex motor will stop and freewheel whenever you stop pedalling, resuming as soon as you start to pedal again.

My Family Waste Disposal Business

This is where I use my Electric Bike the most to and from work

check out the Big Link Below

Guestbook Comments

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    • profile image

      Bartukas 4 years ago

      Wow very interesting and nice lens! thanks for sharing

    • profile image

      anonymous 4 years ago

      Nice guide, bud! Keep up the nice work.

    • profile image

      adrianJB 4 years ago

      Really good info about drive types and batteries. I had been searching for just this overview.

    • Coffee-Break profile image

      Dorian Bodnariuc 5 years ago from Ottawa, Ontario Canada

      I am thinking about buying an electric bicycle, but the good quality ones are very expensive. I think I am going to spend the money anyway...

    • Sylvestermouse profile image

      Cynthia Sylvestermouse 5 years ago from United States

      I had never heard of electric bikes before. Very interesting!

    • Countryluthier profile image

      E L Seaton 5 years ago from Virginia

      Nice looking selection of cycles. I hope to ride mass transit and have one stashed at the job just in case I need to dash out between bus runs. Thanks for sharing.

    • Scotties-Rock profile image

      Clairissa 5 years ago from OREFIELD, PA

      Wow! Never even knew they existed! Great lens very interesting.

    • profile image

      Helene-Malmsio 5 years ago

      I bought an electric bike / trike a few years ago on impulse, and it is still sitting in my studio shed, all charged up but nowhere to go - lol! Must get on it one day!

    • profile image

      victorstuler 5 years ago

      They are generically environment friendly since they do not suffer from any toxic emissions like motor vehicles. They also save expenses on petroleum which is becoming costlier every year, thus saving foreign exchange for several countries that are forced to import oil from OPEC countries. They are almost silent and do not cause noise pollution further saving people and environment. They are known to have health benefits for persons with cardiac disorders. They are relatively more secure as they cannot be moved once the electric switch is turned into OFF position. It is therefore, small wonder that many countries such as Australia, Canada, European Union, New Zealand and USA are encouraging their use.

      electric bikes

    • profile image

      JoshK47 5 years ago

      Never knew electric bikes existed - learn something new every day!